Merge pull request #714 from louis-e/revert-sequential-streaming

Revert sequential streaming saving since generation speed was affected

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
             target: x86_64-unknown-linux-gnu
             binary_name: arnis
             asset_name: arnis-linux
-          - os: macos-13  # Intel runner for x86_64 builds
+          - os: macos-15-intel  # Intel runner for x86_64 builds
             target: x86_64-apple-darwin
             binary_name: arnis
             asset_name: arnis-mac-intel
@@ -87,7 +87,7 @@ jobs:
       shell: powershell
 
     - name: Upload artifact
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: ${{ matrix.os }}-${{ matrix.target }}-build
         path: target/release/${{ matrix.asset_name }}
@@ -97,13 +97,13 @@ jobs:
     runs-on: macos-latest
     steps:
     - name: Download macOS Intel build
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v7
       with:
-        name: macos-13-x86_64-apple-darwin-build
+        name: macos-15-intel-x86_64-apple-darwin-build
         path: ./intel
 
     - name: Download macOS ARM64 build
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v7
       with:
         name: macos-latest-aarch64-apple-darwin-build
         path: ./arm64
@@ -114,7 +114,7 @@ jobs:
         chmod +x arnis-mac-universal
 
     - name: Upload universal binary
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: macos-universal-build
         path: arnis-mac-universal
@@ -127,19 +127,19 @@ jobs:
       uses: actions/checkout@v6
 
     - name: Download Windows build artifact
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v7
       with:
         name: windows-latest-x86_64-pc-windows-msvc-build
         path: ./builds/windows
 
     - name: Download Linux build artifact
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v7
       with:
         name: ubuntu-latest-x86_64-unknown-linux-gnu-build
         path: ./builds/linux
 
     - name: Download macOS universal build artifact
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v7
       with:
         name: macos-universal-build
         path: ./builds/macos
@@ -157,4 +157,4 @@ jobs:
           builds/linux/arnis-linux
           builds/macos/arnis-mac-universal
       env:
-        GITHUB_TOKEN: ${{ secrets.RELEASE_TOKEN }}
+        GITHUB_TOKEN: ${{ secrets.RELEASE_TOKEN }}

Cargo.lock

@@ -182,7 +182,7 @@ dependencies = [
 
 [[package]]
 name = "arnis"
-version = "2.4.0"
+version = "2.4.1"
 dependencies = [
  "base64 0.22.1",
  "bedrockrs_level",
@@ -204,6 +204,7 @@ dependencies = [
  "nbtx",
  "once_cell",
  "rand 0.8.5",
+ "rand_chacha 0.3.1",
  "rayon",
  "reqwest",
  "rfd",
@@ -4487,9 +4488,9 @@ dependencies = [
 
 [[package]]
 name = "rfd"
-version = "0.15.4"
+version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef2bee61e6cffa4635c72d7d81a84294e28f0930db0ddcb0f66d10244674ebed"
+checksum = "a15ad77d9e70a92437d8f74c35d99b4e4691128df018833e99f90bcd36152672"
 dependencies = [
  "ashpd",
  "block2 0.6.1",
@@ -4506,7 +4507,7 @@ dependencies = [
  "wasm-bindgen",
  "wasm-bindgen-futures",
  "web-sys",
- "windows-sys 0.59.0",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -6765,6 +6766,15 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2f500e4d28234f72040990ec9d39e3a6b950f9f22d3dba18416c35882612bcb"
+dependencies = [
+ "windows-targets 0.53.2",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.61.2"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "arnis"
-version = "2.4.0"
+version = "2.4.1"
 edition = "2021"
 description = "Arnis - Generate real life cities in Minecraft"
 homepage = "https://github.com/louis-e/arnis"
@@ -38,9 +38,10 @@ itertools = "0.14.0"
 log = "0.4.27"
 once_cell = "1.21.3"
 rand = "0.8.5"
+rand_chacha = "0.3"
 rayon = "1.10.0"
 reqwest = { version = "0.12.15", features = ["blocking", "json"] }
-rfd = { version = "0.15.4", optional = true }
+rfd = { version = "0.16.0", optional = true }
 semver = "1.0.27"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"

README.md

@@ -63,6 +63,8 @@ Arnis has been recognized in various academic and press publications after gaini
 
 [XDA Developers: Hometown Minecraft Map: Arnis](https://www.xda-developers.com/hometown-minecraft-map-arnis/)
 
+Free to use assets, including screenshots and logos, can be found [here](https://drive.google.com/file/d/1T1IsZSyT8oa6qAO_40hVF5KR8eEVCJjo/view?usp=sharing).
+
 ## :copyright: License Information
 Copyright (c) 2022-2025 Louis Erbkamm (louis-e)
 

src/args.rs

@@ -58,10 +58,6 @@ pub struct Args {
     /// Set floodfill timeout (seconds) (optional)
     #[arg(long, value_parser = parse_duration)]
     pub timeout: Option<Duration>,
-
-    /// Spawn point coordinates (lat, lng)
-    #[arg(skip)]
-    pub spawn_point: Option<(f64, f64)>,
 }
 
 fn validate_minecraft_world_path(path: &str) -> Result<PathBuf, String> {

src/block_definitions.rs

@@ -266,6 +266,7 @@ impl Block {
             185 => "quartz_stairs",
             186 => "polished_andesite_stairs",
             187 => "nether_brick_stairs",
+            188 => "fern",
             _ => panic!("Invalid id"),
         }
     }
@@ -697,6 +698,7 @@ pub const SMOOTH_SANDSTONE_STAIRS: Block = Block::new(184);
 pub const QUARTZ_STAIRS: Block = Block::new(185);
 pub const POLISHED_ANDESITE_STAIRS: Block = Block::new(186);
 pub const NETHER_BRICK_STAIRS: Block = Block::new(187);
+pub const FERN: Block = Block::new(188);
 
 /// Maps a block to its corresponding stair variant
 #[inline]

src/data_processing.rs

@@ -3,6 +3,7 @@ use crate::block_definitions::{BEDROCK, DIRT, GRASS_BLOCK, STONE};
 use crate::coordinate_system::cartesian::XZBBox;
 use crate::coordinate_system::geographic::LLBBox;
 use crate::element_processing::*;
+use crate::floodfill_cache::FloodFillCache;
 use crate::ground::Ground;
 use crate::map_renderer;
 use crate::osm_parser::ProcessedElement;
@@ -13,6 +14,7 @@ use crate::world_editor::{WorldEditor, WorldFormat};
 use colored::Colorize;
 use indicatif::{ProgressBar, ProgressStyle};
 use std::path::PathBuf;
+use std::sync::Arc;
 
 pub const MIN_Y: i32 = -64;
 
@@ -53,14 +55,17 @@ pub fn generate_world_with_options(
 ) -> Result<PathBuf, String> {
     let output_path = options.path.clone();
     let world_format = options.format;
+
+    // Create editor with appropriate format
     let mut editor: WorldEditor = WorldEditor::new_with_format_and_name(
         options.path,
         &xzbbox,
         llbbox,
         options.format,
-        options.level_name,
+        options.level_name.clone(),
         options.spawn_point,
     );
+    let ground = Arc::new(ground);
 
     println!("{} Processing data...", "[4/7]".bold());
 
@@ -68,13 +73,21 @@ pub fn generate_world_with_options(
     let highway_connectivity = highways::build_highway_connectivity_map(&elements);
 
     // Set ground reference in the editor to enable elevation-aware block placement
-    editor.set_ground(&ground);
+    editor.set_ground(Arc::clone(&ground));
 
     println!("{} Processing terrain...", "[5/7]".bold());
     emit_gui_progress_update(25.0, "Processing terrain...");
 
+    // Pre-compute all flood fills in parallel for better CPU utilization
+    let mut flood_fill_cache = FloodFillCache::precompute(&elements, args.timeout.as_ref());
+
+    // Collect building footprints to prevent trees from spawning inside buildings
+    // Uses a memory-efficient bitmap (~1 bit per coordinate) instead of a HashSet (~24 bytes per coordinate)
+    let building_footprints = flood_fill_cache.collect_building_footprints(&elements, &xzbbox);
+
     // Process data
     let elements_count: usize = elements.len();
+    let mut elements = elements; // Take ownership for consuming
     let process_pb: ProgressBar = ProgressBar::new(elements_count as u64);
     process_pb.set_style(ProgressStyle::default_bar()
         .template("{spinner:.green} [{elapsed_precise}] [{bar:45.white/black}] {pos}/{len} elements ({eta}) {msg}")
@@ -85,7 +98,8 @@ pub fn generate_world_with_options(
     let mut current_progress_prcs: f64 = 25.0;
     let mut last_emitted_progress: f64 = current_progress_prcs;
 
-    for element in &elements {
+    // Process elements by draining in insertion order
+    for element in elements.drain(..) {
         process_pb.inc(1);
         current_progress_prcs += progress_increment_prcs;
         if (current_progress_prcs - last_emitted_progress).abs() > 0.25 {
@@ -103,22 +117,46 @@ pub fn generate_world_with_options(
             process_pb.set_message("");
         }
 
-        match element {
+        match &element {
             ProcessedElement::Way(way) => {
                 if way.tags.contains_key("building") || way.tags.contains_key("building:part") {
-                    buildings::generate_buildings(&mut editor, way, args, None);
+                    buildings::generate_buildings(&mut editor, way, args, None, &flood_fill_cache);
                 } else if way.tags.contains_key("highway") {
-                    highways::generate_highways(&mut editor, element, args, &highway_connectivity);
+                    highways::generate_highways(
+                        &mut editor,
+                        &element,
+                        args,
+                        &highway_connectivity,
+                        &flood_fill_cache,
+                    );
                 } else if way.tags.contains_key("landuse") {
-                    landuse::generate_landuse(&mut editor, way, args);
+                    landuse::generate_landuse(
+                        &mut editor,
+                        way,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
                 } else if way.tags.contains_key("natural") {
-                    natural::generate_natural(&mut editor, element, args);
+                    natural::generate_natural(
+                        &mut editor,
+                        &element,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
                 } else if way.tags.contains_key("amenity") {
-                    amenities::generate_amenities(&mut editor, element, args);
+                    amenities::generate_amenities(&mut editor, &element, args, &flood_fill_cache);
                 } else if way.tags.contains_key("leisure") {
-                    leisure::generate_leisure(&mut editor, way, args);
+                    leisure::generate_leisure(
+                        &mut editor,
+                        way,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
                 } else if way.tags.contains_key("barrier") {
-                    barriers::generate_barriers(&mut editor, element);
+                    barriers::generate_barriers(&mut editor, &element);
                 } else if let Some(val) = way.tags.get("waterway") {
                     if val == "dock" {
                         // docks count as water areas
@@ -138,8 +176,10 @@ pub fn generate_world_with_options(
                 } else if way.tags.get("service") == Some(&"siding".to_string()) {
                     highways::generate_siding(&mut editor, way);
                 } else if way.tags.contains_key("man_made") {
-                    man_made::generate_man_made(&mut editor, element, args);
+                    man_made::generate_man_made(&mut editor, &element, args);
                 }
+                // Release flood fill cache entry for this way
+                flood_fill_cache.remove_way(way.id);
             }
             ProcessedElement::Node(node) => {
                 if node.tags.contains_key("door") || node.tags.contains_key("entrance") {
@@ -147,13 +187,25 @@ pub fn generate_world_with_options(
                 } else if node.tags.contains_key("natural")
                     && node.tags.get("natural") == Some(&"tree".to_string())
                 {
-                    natural::generate_natural(&mut editor, element, args);
+                    natural::generate_natural(
+                        &mut editor,
+                        &element,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
                 } else if node.tags.contains_key("amenity") {
-                    amenities::generate_amenities(&mut editor, element, args);
+                    amenities::generate_amenities(&mut editor, &element, args, &flood_fill_cache);
                 } else if node.tags.contains_key("barrier") {
                     barriers::generate_barrier_nodes(&mut editor, node);
                 } else if node.tags.contains_key("highway") {
-                    highways::generate_highways(&mut editor, element, args, &highway_connectivity);
+                    highways::generate_highways(
+                        &mut editor,
+                        &element,
+                        args,
+                        &highway_connectivity,
+                        &flood_fill_cache,
+                    );
                 } else if node.tags.contains_key("tourism") {
                     tourisms::generate_tourisms(&mut editor, node);
                 } else if node.tags.contains_key("man_made") {
@@ -162,7 +214,12 @@ pub fn generate_world_with_options(
             }
             ProcessedElement::Relation(rel) => {
                 if rel.tags.contains_key("building") || rel.tags.contains_key("building:part") {
-                    buildings::generate_building_from_relation(&mut editor, rel, args);
+                    buildings::generate_building_from_relation(
+                        &mut editor,
+                        rel,
+                        args,
+                        &flood_fill_cache,
+                    );
                 } else if rel.tags.contains_key("water")
                     || rel
                         .tags
@@ -172,24 +229,46 @@ pub fn generate_world_with_options(
                 {
                     water_areas::generate_water_areas_from_relation(&mut editor, rel, &xzbbox);
                 } else if rel.tags.contains_key("natural") {
-                    natural::generate_natural_from_relation(&mut editor, rel, args);
-                } else if rel.tags.contains_key("landuse") {
-                    landuse::generate_landuse_from_relation(&mut editor, rel, args);
-                } else if rel.tags.get("leisure") == Some(&"park".to_string()) {
-                    leisure::generate_leisure_from_relation(&mut editor, rel, args);
-                } else if rel.tags.contains_key("man_made") {
-                    man_made::generate_man_made(
+                    natural::generate_natural_from_relation(
                         &mut editor,
-                        &ProcessedElement::Relation(rel.clone()),
+                        rel,
                         args,
+                        &flood_fill_cache,
+                        &building_footprints,
                     );
+                } else if rel.tags.contains_key("landuse") {
+                    landuse::generate_landuse_from_relation(
+                        &mut editor,
+                        rel,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
+                } else if rel.tags.get("leisure") == Some(&"park".to_string()) {
+                    leisure::generate_leisure_from_relation(
+                        &mut editor,
+                        rel,
+                        args,
+                        &flood_fill_cache,
+                        &building_footprints,
+                    );
+                } else if rel.tags.contains_key("man_made") {
+                    man_made::generate_man_made(&mut editor, &element, args);
                 }
+                // Release flood fill cache entries for all ways in this relation
+                let way_ids: Vec<u64> = rel.members.iter().map(|m| m.way.id).collect();
+                flood_fill_cache.remove_relation_ways(&way_ids);
             }
         }
+        // Element is dropped here, freeing its memory immediately
     }
 
     process_pb.finish();
 
+    // Drop remaining caches
+    drop(highway_connectivity);
+    drop(flood_fill_cache);
+
     // Generate ground layer
     let total_blocks: u64 = xzbbox.bounding_rect().total_blocks();
     let desired_updates: u64 = 1500;
@@ -213,46 +292,72 @@ pub fn generate_world_with_options(
     let total_iterations_grnd: f64 = total_blocks as f64;
     let progress_increment_grnd: f64 = 20.0 / total_iterations_grnd;
 
-    let groundlayer_block = GRASS_BLOCK;
+    // Check if terrain elevation is enabled; when disabled, we can skip ground level lookups entirely
+    let terrain_enabled = ground.elevation_enabled;
 
-    for x in xzbbox.min_x()..=xzbbox.max_x() {
-        for z in xzbbox.min_z()..=xzbbox.max_z() {
-            // Add default dirt and grass layer if there isn't a stone layer already
-            if !editor.check_for_block(x, 0, z, Some(&[STONE])) {
-                editor.set_block(groundlayer_block, x, 0, z, None, None);
-                editor.set_block(DIRT, x, -1, z, None, None);
-                editor.set_block(DIRT, x, -2, z, None, None);
-            }
+    // Process ground generation chunk-by-chunk for better cache locality.
+    // This keeps the same region/chunk HashMap entries hot in CPU cache,
+    // rather than jumping between regions on every Z iteration.
+    let min_chunk_x = xzbbox.min_x() >> 4;
+    let max_chunk_x = xzbbox.max_x() >> 4;
+    let min_chunk_z = xzbbox.min_z() >> 4;
+    let max_chunk_z = xzbbox.max_z() >> 4;
 
-            // Fill underground with stone
-            if args.fillground {
-                // Fill from bedrock+1 to 3 blocks below ground with stone
-                editor.fill_blocks_absolute(
-                    STONE,
-                    x,
-                    MIN_Y + 1,
-                    z,
-                    x,
-                    editor.get_absolute_y(x, -3, z),
-                    z,
-                    None,
-                    None,
-                );
-            }
-            // Generate a bedrock level at MIN_Y
-            editor.set_block_absolute(BEDROCK, x, MIN_Y, z, None, Some(&[BEDROCK]));
+    for chunk_x in min_chunk_x..=max_chunk_x {
+        for chunk_z in min_chunk_z..=max_chunk_z {
+            // Calculate the block range for this chunk, clamped to bbox
+            let chunk_min_x = (chunk_x << 4).max(xzbbox.min_x());
+            let chunk_max_x = ((chunk_x << 4) + 15).min(xzbbox.max_x());
+            let chunk_min_z = (chunk_z << 4).max(xzbbox.min_z());
+            let chunk_max_z = ((chunk_z << 4) + 15).min(xzbbox.max_z());
 
-            block_counter += 1;
-            // Use manual % check since is_multiple_of() is unstable on stable Rust
-            #[allow(clippy::manual_is_multiple_of)]
-            if block_counter % batch_size == 0 {
-                ground_pb.inc(batch_size);
-            }
+            for x in chunk_min_x..=chunk_max_x {
+                for z in chunk_min_z..=chunk_max_z {
+                    // Get ground level, when terrain is enabled, look it up once per block
+                    // When disabled, use constant ground_level (no function call overhead)
+                    let ground_y = if terrain_enabled {
+                        editor.get_ground_level(x, z)
+                    } else {
+                        args.ground_level
+                    };
 
-            gui_progress_grnd += progress_increment_grnd;
-            if (gui_progress_grnd - last_emitted_progress).abs() > 0.25 {
-                emit_gui_progress_update(gui_progress_grnd, "");
-                last_emitted_progress = gui_progress_grnd;
+                    // Add default dirt and grass layer if there isn't a stone layer already
+                    if !editor.check_for_block_absolute(x, ground_y, z, Some(&[STONE]), None) {
+                        editor.set_block_absolute(GRASS_BLOCK, x, ground_y, z, None, None);
+                        editor.set_block_absolute(DIRT, x, ground_y - 1, z, None, None);
+                        editor.set_block_absolute(DIRT, x, ground_y - 2, z, None, None);
+                    }
+
+                    // Fill underground with stone
+                    if args.fillground {
+                        // Fill from bedrock+1 to 3 blocks below ground with stone
+                        editor.fill_blocks_absolute(
+                            STONE,
+                            x,
+                            MIN_Y + 1,
+                            z,
+                            x,
+                            ground_y - 3,
+                            z,
+                            None,
+                            None,
+                        );
+                    }
+                    // Generate a bedrock level at MIN_Y
+                    editor.set_block_absolute(BEDROCK, x, MIN_Y, z, None, Some(&[BEDROCK]));
+
+                    block_counter += 1;
+                    #[allow(clippy::manual_is_multiple_of)]
+                    if block_counter % batch_size == 0 {
+                        ground_pb.inc(batch_size);
+                    }
+
+                    gui_progress_grnd += progress_increment_grnd;
+                    if (gui_progress_grnd - last_emitted_progress).abs() > 0.25 {
+                        emit_gui_progress_update(gui_progress_grnd, "");
+                        last_emitted_progress = gui_progress_grnd;
+                    }
+                }
             }
         }
     }
@@ -275,36 +380,36 @@ pub fn generate_world_with_options(
     // Save world
     editor.save();
 
+    emit_gui_progress_update(99.0, "Finalizing world...");
+
     // Update player spawn Y coordinate based on terrain height after generation
     #[cfg(feature = "gui")]
     if world_format == WorldFormat::JavaAnvil {
-        if let Some(spawn_coords) = &args.spawn_point {
-            use crate::gui::update_player_spawn_y_after_generation;
-            let bbox_string = format!(
-                "{},{},{},{}",
-                args.bbox.min().lng(),
-                args.bbox.min().lat(),
-                args.bbox.max().lng(),
-                args.bbox.max().lat()
-            );
+        use crate::gui::update_player_spawn_y_after_generation;
+        // Reconstruct bbox string to match the format that GUI originally provided.
+        // This ensures LLBBox::from_str() can parse it correctly.
+        let bbox_string = format!(
+            "{},{},{},{}",
+            args.bbox.min().lat(),
+            args.bbox.min().lng(),
+            args.bbox.max().lat(),
+            args.bbox.max().lng()
+        );
 
-            if let Err(e) = update_player_spawn_y_after_generation(
-                &args.path,
-                Some(*spawn_coords),
-                bbox_string,
-                args.scale,
-                &ground,
-            ) {
-                let warning_msg = format!("Failed to update spawn point Y coordinate: {}", e);
-                eprintln!("Warning: {}", warning_msg);
-                #[cfg(feature = "gui")]
-                send_log(LogLevel::Warning, &warning_msg);
-            }
+        // Always update spawn Y since we now always set a spawn point (user-selected or default)
+        if let Err(e) = update_player_spawn_y_after_generation(
+            &args.path,
+            bbox_string,
+            args.scale,
+            ground.as_ref(),
+        ) {
+            let warning_msg = format!("Failed to update spawn point Y coordinate: {}", e);
+            eprintln!("Warning: {}", warning_msg);
+            #[cfg(feature = "gui")]
+            send_log(LogLevel::Warning, &warning_msg);
         }
     }
 
-    emit_gui_progress_update(99.0, "Finalizing world...");
-
     // For Bedrock format, emit event to open the mcworld file
     if world_format == WorldFormat::BedrockMcWorld {
         if let Some(path_str) = output_path.to_str() {
@@ -312,41 +417,72 @@ pub fn generate_world_with_options(
         }
     }
 
-    // Generate top-down map preview silently in background after completion (Java only)
-    // Skip map preview for very large areas to avoid memory issues
-    const MAX_MAP_PREVIEW_AREA: i64 = 6400 * 6900;
-    let world_width = (xzbbox.max_x() - xzbbox.min_x()) as i64;
-    let world_height = (xzbbox.max_z() - xzbbox.min_z()) as i64;
-    let world_area = world_width * world_height;
-
-    if world_format == WorldFormat::JavaAnvil && world_area <= MAX_MAP_PREVIEW_AREA {
-        let world_path = args.path.clone();
-        let bounds = (
-            xzbbox.min_x(),
-            xzbbox.max_x(),
-            xzbbox.min_z(),
-            xzbbox.max_z(),
-        );
-        std::thread::spawn(move || {
-            // Use catch_unwind to prevent any panic from affecting the application
-            let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
-                map_renderer::render_world_map(&world_path, bounds.0, bounds.1, bounds.2, bounds.3)
-            }));
-
-            match result {
-                Ok(Ok(_path)) => {
-                    // Notify the GUI that the map preview is ready
-                    emit_map_preview_ready();
-                }
-                Ok(Err(e)) => {
-                    eprintln!("Warning: Failed to generate map preview: {}", e);
-                }
-                Err(_) => {
-                    eprintln!("Warning: Map preview generation panicked unexpectedly");
-                }
-            }
-        });
-    }
-
     Ok(output_path)
 }
+
+/// Information needed to generate a map preview after world generation is complete
+#[derive(Clone)]
+pub struct MapPreviewInfo {
+    pub world_path: PathBuf,
+    pub min_x: i32,
+    pub max_x: i32,
+    pub min_z: i32,
+    pub max_z: i32,
+    pub world_area: i64,
+}
+
+impl MapPreviewInfo {
+    /// Create MapPreviewInfo from world bounds
+    pub fn new(world_path: PathBuf, xzbbox: &XZBBox) -> Self {
+        let world_width = (xzbbox.max_x() - xzbbox.min_x()) as i64;
+        let world_height = (xzbbox.max_z() - xzbbox.min_z()) as i64;
+        Self {
+            world_path,
+            min_x: xzbbox.min_x(),
+            max_x: xzbbox.max_x(),
+            min_z: xzbbox.min_z(),
+            max_z: xzbbox.max_z(),
+            world_area: world_width * world_height,
+        }
+    }
+}
+
+/// Maximum area for which map preview generation is allowed (to avoid memory issues)
+pub const MAX_MAP_PREVIEW_AREA: i64 = 6400 * 6900;
+
+/// Start map preview generation in a background thread.
+/// This should be called AFTER the world generation is complete, the session lock is released,
+/// and the GUI has been notified of 100% completion.
+///
+/// For Java worlds only, and only if the world area is within limits.
+pub fn start_map_preview_generation(info: MapPreviewInfo) {
+    if info.world_area > MAX_MAP_PREVIEW_AREA {
+        return;
+    }
+
+    std::thread::spawn(move || {
+        // Use catch_unwind to prevent any panic from affecting the application
+        let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
+            map_renderer::render_world_map(
+                &info.world_path,
+                info.min_x,
+                info.max_x,
+                info.min_z,
+                info.max_z,
+            )
+        }));
+
+        match result {
+            Ok(Ok(_path)) => {
+                // Notify the GUI that the map preview is ready
+                emit_map_preview_ready();
+            }
+            Ok(Err(e)) => {
+                eprintln!("Warning: Failed to generate map preview: {}", e);
+            }
+            Err(_) => {
+                eprintln!("Warning: Map preview generation panicked unexpectedly");
+            }
+        }
+    });
+}

src/deterministic_rng.rs

@@ -0,0 +1,127 @@
+//! Deterministic random number generation for consistent element processing.
+//!
+//! This module provides seeded RNG that ensures the same element always produces
+//! the same random values, regardless of processing order. This is essential for
+//! region-by-region streaming where the same element may be processed multiple times
+//! (once for each region it touches).
+//!
+//! # Example
+//! ```ignore
+//! let mut rng = element_rng(element_id);
+//! let color = rng.gen_bool(0.5); // Always same result for same element_id
+//! ```
+
+use rand::SeedableRng;
+use rand_chacha::ChaCha8Rng;
+
+/// Creates a deterministic RNG seeded from an element ID.
+///
+/// The same element ID will always produce the same sequence of random values,
+/// ensuring consistent results when an element is processed multiple times
+/// (e.g., once per region it touches during streaming).
+///
+/// # Arguments
+/// * `element_id` - The unique OSM element ID (way ID, node ID, or relation ID)
+///
+/// # Returns
+/// A seeded ChaCha8Rng that will produce deterministic random values
+#[inline]
+pub fn element_rng(element_id: u64) -> ChaCha8Rng {
+    ChaCha8Rng::seed_from_u64(element_id)
+}
+
+/// Creates a deterministic RNG seeded from an element ID with an additional salt.
+///
+/// Use this when you need multiple independent random sequences for the same element.
+/// For example, one sequence for wall colors and another for roof style.
+///
+/// # Arguments
+/// * `element_id` - The unique OSM element ID
+/// * `salt` - Additional value to create a different sequence (e.g., use different
+///   salt values for different purposes within the same element)
+#[inline]
+#[allow(dead_code)]
+pub fn element_rng_salted(element_id: u64, salt: u64) -> ChaCha8Rng {
+    // Combine element_id and salt using XOR and bit rotation to avoid collisions
+    let combined = element_id ^ salt.rotate_left(32);
+    ChaCha8Rng::seed_from_u64(combined)
+}
+
+/// Creates a deterministic RNG seeded from coordinates.
+///
+/// Use this for per-block randomness that needs to be consistent regardless
+/// of processing order (e.g., random flower placement within a natural area).
+///
+/// # Arguments
+/// * `x` - X coordinate
+/// * `z` - Z coordinate
+/// * `element_id` - The element ID for additional uniqueness
+#[inline]
+pub fn coord_rng(x: i32, z: i32, element_id: u64) -> ChaCha8Rng {
+    // Combine coordinates and element_id into a seed.
+    // Cast through u32 to handle negative coordinates consistently.
+    let coord_part = ((x as u32 as i64) << 32) | (z as u32 as i64);
+    let seed = (coord_part as u64) ^ element_id;
+    ChaCha8Rng::seed_from_u64(seed)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rand::Rng;
+
+    #[test]
+    fn test_element_rng_deterministic() {
+        let mut rng1 = element_rng(12345);
+        let mut rng2 = element_rng(12345);
+
+        // Same seed should produce same sequence
+        for _ in 0..100 {
+            assert_eq!(rng1.gen::<u64>(), rng2.gen::<u64>());
+        }
+    }
+
+    #[test]
+    fn test_different_elements_different_values() {
+        let mut rng1 = element_rng(12345);
+        let mut rng2 = element_rng(12346);
+
+        // Different seeds should (almost certainly) produce different values
+        let v1: u64 = rng1.gen();
+        let v2: u64 = rng2.gen();
+        assert_ne!(v1, v2);
+    }
+
+    #[test]
+    fn test_salted_rng_different_from_base() {
+        let mut rng1 = element_rng(12345);
+        let mut rng2 = element_rng_salted(12345, 1);
+
+        let v1: u64 = rng1.gen();
+        let v2: u64 = rng2.gen();
+        assert_ne!(v1, v2);
+    }
+
+    #[test]
+    fn test_coord_rng_deterministic() {
+        let mut rng1 = coord_rng(100, 200, 12345);
+        let mut rng2 = coord_rng(100, 200, 12345);
+
+        assert_eq!(rng1.gen::<u64>(), rng2.gen::<u64>());
+    }
+
+    #[test]
+    fn test_coord_rng_negative_coordinates() {
+        // Negative coordinates are common in Minecraft worlds
+        let mut rng1 = coord_rng(-100, -200, 12345);
+        let mut rng2 = coord_rng(-100, -200, 12345);
+
+        assert_eq!(rng1.gen::<u64>(), rng2.gen::<u64>());
+
+        // Ensure different negative coords produce different seeds
+        let mut rng3 = coord_rng(-100, -200, 12345);
+        let mut rng4 = coord_rng(-101, -200, 12345);
+
+        assert_ne!(rng3.gen::<u64>(), rng4.gen::<u64>());
+    }
+}

src/element_processing/amenities.rs

@@ -2,11 +2,19 @@ use crate::args::Args;
 use crate::block_definitions::*;
 use crate::bresenham::bresenham_line;
 use crate::coordinate_system::cartesian::XZPoint;
-use crate::floodfill::flood_fill_area;
+use crate::deterministic_rng::element_rng;
+use crate::floodfill::flood_fill_area; // Needed for inline amenity flood fills
+use crate::floodfill_cache::FloodFillCache;
 use crate::osm_parser::ProcessedElement;
 use crate::world_editor::WorldEditor;
+use rand::Rng;
 
-pub fn generate_amenities(editor: &mut WorldEditor, element: &ProcessedElement, args: &Args) {
+pub fn generate_amenities(
+    editor: &mut WorldEditor,
+    element: &ProcessedElement,
+    args: &Args,
+    flood_fill_cache: &FloodFillCache,
+) {
     // Skip if 'layer' or 'level' is negative in the tags
     if let Some(layer) = element.tags().get("layer") {
         if layer.parse::<i32>().unwrap_or(0) < 0 {
@@ -42,18 +50,14 @@ pub fn generate_amenities(editor: &mut WorldEditor, element: &ProcessedElement,
                 let ground_block: Block = OAK_PLANKS;
                 let roof_block: Block = STONE_BLOCK_SLAB;
 
-                let polygon_coords: Vec<(i32, i32)> = element
-                    .nodes()
-                    .map(|n: &crate::osm_parser::ProcessedNode| (n.x, n.z))
-                    .collect();
+                // Use pre-computed flood fill from cache
+                let floor_area: Vec<(i32, i32)> =
+                    flood_fill_cache.get_or_compute_element(element, args.timeout.as_ref());
 
-                if polygon_coords.is_empty() {
+                if floor_area.is_empty() {
                     return;
                 }
 
-                let floor_area: Vec<(i32, i32)> =
-                    flood_fill_area(&polygon_coords, args.timeout.as_ref());
-
                 // Fill the floor area
                 for (x, z) in floor_area.iter() {
                     editor.set_block(ground_block, *x, 0, *z, None, None);
@@ -80,8 +84,10 @@ pub fn generate_amenities(editor: &mut WorldEditor, element: &ProcessedElement,
             "bench" => {
                 // Place a bench
                 if let Some(pt) = first_node {
-                    // 50% chance to 90 degrees rotate the bench using if
-                    if rand::random::<bool>() {
+                    // Use deterministic RNG for consistent bench orientation across region boundaries
+                    let mut rng = element_rng(element.id());
+                    // 50% chance to 90 degrees rotate the bench
+                    if rng.gen_bool(0.5) {
                         editor.set_block(SMOOTH_STONE, pt.x, 1, pt.z, None, None);
                         editor.set_block(OAK_LOG, pt.x + 1, 1, pt.z, None, None);
                         editor.set_block(OAK_LOG, pt.x - 1, 1, pt.z, None, None);
@@ -95,12 +101,9 @@ pub fn generate_amenities(editor: &mut WorldEditor, element: &ProcessedElement,
             "shelter" => {
                 let roof_block: Block = STONE_BRICK_SLAB;
 
-                let polygon_coords: Vec<(i32, i32)> = element
-                    .nodes()
-                    .map(|n: &crate::osm_parser::ProcessedNode| (n.x, n.z))
-                    .collect();
+                // Use pre-computed flood fill from cache
                 let roof_area: Vec<(i32, i32)> =
-                    flood_fill_area(&polygon_coords, args.timeout.as_ref());
+                    flood_fill_cache.get_or_compute_element(element, args.timeout.as_ref());
 
                 // Place fences and roof slabs at each corner node directly
                 for node in element.nodes() {

src/element_processing/bridges.rs

@@ -3,37 +3,97 @@ use crate::bresenham::bresenham_line;
 use crate::osm_parser::ProcessedWay;
 use crate::world_editor::WorldEditor;
 
-// TODO FIX
+// TODO FIX - This handles ways with bridge=yes tag (e.g., highway bridges)
 #[allow(dead_code)]
 pub fn generate_bridges(editor: &mut WorldEditor, element: &ProcessedWay) {
     if let Some(_bridge_type) = element.tags.get("bridge") {
-        let bridge_height = 3; // Fixed height
+        let bridge_height = 3; // Height above the ground level
+
+        // Get start and end node elevations and use MAX for level bridge deck
+        // Using MAX ensures bridges don't dip when multiple bridge ways meet in a valley
+        let bridge_deck_ground_y = if element.nodes.len() >= 2 {
+            let start_node = &element.nodes[0];
+            let end_node = &element.nodes[element.nodes.len() - 1];
+            let start_y = editor.get_ground_level(start_node.x, start_node.z);
+            let end_y = editor.get_ground_level(end_node.x, end_node.z);
+            start_y.max(end_y)
+        } else {
+            return; // Need at least 2 nodes for a bridge
+        };
+
+        // Calculate total bridge length for ramp positioning
+        let total_length: f64 = element
+            .nodes
+            .windows(2)
+            .map(|pair| {
+                let dx = (pair[1].x - pair[0].x) as f64;
+                let dz = (pair[1].z - pair[0].z) as f64;
+                (dx * dx + dz * dz).sqrt()
+            })
+            .sum();
+
+        if total_length == 0.0 {
+            return;
+        }
+
+        let mut accumulated_length: f64 = 0.0;
 
         for i in 1..element.nodes.len() {
             let prev = &element.nodes[i - 1];
             let cur = &element.nodes[i];
+
+            let segment_dx = (cur.x - prev.x) as f64;
+            let segment_dz = (cur.z - prev.z) as f64;
+            let segment_length = (segment_dx * segment_dx + segment_dz * segment_dz).sqrt();
+
             let points = bresenham_line(prev.x, 0, prev.z, cur.x, 0, cur.z);
 
-            let total_length = points.len();
-            let ramp_length = 6; // Length of ramp at each end
+            let ramp_length = (total_length * 0.15).clamp(6.0, 20.0) as usize; // 15% of bridge, min 6, max 20 blocks
 
             for (idx, (x, _, z)) in points.iter().enumerate() {
-                let height = if idx < ramp_length {
+                // Calculate progress along this segment
+                let segment_progress = if points.len() > 1 {
+                    idx as f64 / (points.len() - 1) as f64
+                } else {
+                    0.0
+                };
+
+                // Calculate overall progress along the entire bridge
+                let point_distance = accumulated_length + segment_progress * segment_length;
+                let overall_progress = (point_distance / total_length).clamp(0.0, 1.0);
+                let total_len_usize = total_length as usize;
+                let overall_idx = (overall_progress * total_len_usize as f64) as usize;
+
+                // Calculate ramp height offset
+                let ramp_offset = if overall_idx < ramp_length {
                     // Start ramp (rising)
-                    (idx * bridge_height) / ramp_length
-                } else if idx >= total_length - ramp_length {
+                    (overall_idx as f64 * bridge_height as f64 / ramp_length as f64) as i32
+                } else if overall_idx >= total_len_usize.saturating_sub(ramp_length) {
                     // End ramp (descending)
-                    ((total_length - idx) * bridge_height) / ramp_length
+                    let dist_from_end = total_len_usize - overall_idx;
+                    (dist_from_end as f64 * bridge_height as f64 / ramp_length as f64) as i32
                 } else {
                     // Middle section (constant height)
                     bridge_height
                 };
 
+                // Use fixed bridge deck height (max of endpoints) plus ramp offset
+                let bridge_y = bridge_deck_ground_y + ramp_offset;
+
                 // Place bridge blocks
                 for dx in -2..=2 {
-                    editor.set_block(LIGHT_GRAY_CONCRETE, *x + dx, height as i32, *z, None, None);
+                    editor.set_block_absolute(
+                        LIGHT_GRAY_CONCRETE,
+                        *x + dx,
+                        bridge_y,
+                        *z,
+                        None,
+                        None,
+                    );
                 }
             }
+
+            accumulated_length += segment_length;
         }
     }
 }

src/element_processing/buildings.rs

@@ -3,8 +3,9 @@ use crate::block_definitions::*;
 use crate::bresenham::bresenham_line;
 use crate::colors::color_text_to_rgb_tuple;
 use crate::coordinate_system::cartesian::XZPoint;
+use crate::deterministic_rng::element_rng;
 use crate::element_processing::subprocessor::buildings_interior::generate_building_interior;
-use crate::floodfill::flood_fill_area;
+use crate::floodfill_cache::FloodFillCache;
 use crate::osm_parser::{ProcessedMemberRole, ProcessedRelation, ProcessedWay};
 use crate::world_editor::WorldEditor;
 use rand::Rng;
@@ -28,6 +29,7 @@ pub fn generate_buildings(
     element: &ProcessedWay,
     args: &Args,
     relation_levels: Option<i32>,
+    flood_fill_cache: &FloodFillCache,
 ) {
     // Get min_level first so we can use it both for start_level and building height calculations
     let min_level = if let Some(min_level_str) = element.tags.get("building:min_level") {
@@ -43,10 +45,9 @@ pub fn generate_buildings(
     let scale_factor = args.scale;
     let min_level_offset = multiply_scale(min_level * 4, scale_factor);
 
-    // Cache floodfill result: compute once and reuse throughout
-    let polygon_coords: Vec<(i32, i32)> = element.nodes.iter().map(|n| (n.x, n.z)).collect();
+    // Use pre-computed flood fill from cache
     let cached_floor_area: Vec<(i32, i32)> =
-        flood_fill_area(&polygon_coords, args.timeout.as_ref());
+        flood_fill_cache.get_or_compute(element, args.timeout.as_ref());
     let cached_footprint_size = cached_floor_area.len();
 
     // Use fixed starting Y coordinate based on maximum ground level when terrain is enabled
@@ -121,7 +122,8 @@ pub fn generate_buildings(
     let mut processed_points: HashSet<(i32, i32)> = HashSet::new();
     let mut building_height: i32 = ((6.0 * scale_factor) as i32).max(3); // Default building height with scale and minimum
     let mut is_tall_building = false;
-    let mut rng = rand::thread_rng();
+    // Use deterministic RNG seeded by element ID for consistent results across region boundaries
+    let mut rng = element_rng(element.id);
     let use_vertical_windows = rng.gen_bool(0.7);
     let use_accent_roof_line = rng.gen_bool(0.25);
 
@@ -386,7 +388,7 @@ pub fn generate_buildings(
                 building_height = ((23.0 * scale_factor) as i32).max(3);
             }
         } else if building_type == "bridge" {
-            generate_bridge(editor, element, args.timeout.as_ref());
+            generate_bridge(editor, element, flood_fill_cache, args.timeout.as_ref());
             return;
         }
     }
@@ -1484,6 +1486,7 @@ pub fn generate_building_from_relation(
     editor: &mut WorldEditor,
     relation: &ProcessedRelation,
     args: &Args,
+    flood_fill_cache: &FloodFillCache,
 ) {
     // Extract levels from relation tags
     let relation_levels = relation
@@ -1495,7 +1498,13 @@ pub fn generate_building_from_relation(
     // Process the outer way to create the building walls
     for member in &relation.members {
         if member.role == ProcessedMemberRole::Outer {
-            generate_buildings(editor, &member.way, args, Some(relation_levels));
+            generate_buildings(
+                editor,
+                &member.way,
+                args,
+                Some(relation_levels),
+                flood_fill_cache,
+            );
         }
     }
 
@@ -1516,52 +1525,18 @@ pub fn generate_building_from_relation(
 }
 
 /// Generates a bridge structure, paying attention to the "level" tag.
+/// Bridge deck is interpolated between start and end point elevations to avoid
+/// being dragged down by valleys underneath.
 fn generate_bridge(
     editor: &mut WorldEditor,
     element: &ProcessedWay,
+    flood_fill_cache: &FloodFillCache,
     floodfill_timeout: Option<&Duration>,
 ) {
     let floor_block: Block = STONE;
     let railing_block: Block = STONE_BRICKS;
 
-    // Process the nodes to create bridge pathways and railings
-    let mut previous_node: Option<(i32, i32)> = None;
-    for node in &element.nodes {
-        let x: i32 = node.x;
-        let z: i32 = node.z;
-
-        // Calculate bridge level based on the "level" tag
-        let bridge_y_offset = if let Some(level_str) = element.tags.get("level") {
-            if let Ok(level) = level_str.parse::<i32>() {
-                (level * 3) + 1
-            } else {
-                1 // Default elevation
-            }
-        } else {
-            1 // Default elevation
-        };
-
-        // Create bridge path using Bresenham's line
-        if let Some(prev) = previous_node {
-            let bridge_points: Vec<(i32, i32, i32)> =
-                bresenham_line(prev.0, bridge_y_offset, prev.1, x, bridge_y_offset, z);
-
-            for (bx, by, bz) in bridge_points {
-                // Place railing blocks
-                editor.set_block(railing_block, bx, by + 1, bz, None, None);
-                editor.set_block(railing_block, bx, by, bz, None, None);
-            }
-        }
-
-        previous_node = Some((x, z));
-    }
-
-    // Flood fill the area between the bridge path nodes
-    let polygon_coords: Vec<(i32, i32)> = element.nodes.iter().map(|n| (n.x, n.z)).collect();
-
-    let bridge_area: Vec<(i32, i32)> = flood_fill_area(&polygon_coords, floodfill_timeout);
-
-    // Calculate bridge level based on the "level" tag
+    // Calculate bridge level offset based on the "level" tag
     let bridge_y_offset = if let Some(level_str) = element.tags.get("level") {
         if let Ok(level) = level_str.parse::<i32>() {
             (level * 3) + 1
@@ -1572,8 +1547,51 @@ fn generate_bridge(
         1 // Default elevation
     };
 
+    // Need at least 2 nodes to form a bridge
+    if element.nodes.len() < 2 {
+        return;
+    }
+
+    // Get start and end node elevations and use MAX for level bridge deck
+    // Using MAX ensures bridges don't dip when multiple bridge ways meet in a valley
+    let start_node = &element.nodes[0];
+    let end_node = &element.nodes[element.nodes.len() - 1];
+    let start_y = editor.get_ground_level(start_node.x, start_node.z);
+    let end_y = editor.get_ground_level(end_node.x, end_node.z);
+    let bridge_deck_ground_y = start_y.max(end_y);
+
+    // Process the nodes to create bridge pathways and railings
+    let mut previous_node: Option<(i32, i32)> = None;
+
+    for node in &element.nodes {
+        let x: i32 = node.x;
+        let z: i32 = node.z;
+
+        // Create bridge path using Bresenham's line
+        if let Some(prev) = previous_node {
+            let bridge_points: Vec<(i32, i32, i32)> = bresenham_line(prev.0, 0, prev.1, x, 0, z);
+
+            for (bx, _, bz) in bridge_points.iter() {
+                // Use fixed bridge deck height (max of endpoints)
+                let bridge_y = bridge_deck_ground_y + bridge_y_offset;
+
+                // Place railing blocks
+                editor.set_block_absolute(railing_block, *bx, bridge_y + 1, *bz, None, None);
+                editor.set_block_absolute(railing_block, *bx, bridge_y, *bz, None, None);
+            }
+        }
+
+        previous_node = Some((x, z));
+    }
+
+    // Flood fill the area between the bridge path nodes (uses cache)
+    let bridge_area: Vec<(i32, i32)> = flood_fill_cache.get_or_compute(element, floodfill_timeout);
+
+    // Use the same level bridge deck height for filled areas
+    let floor_y = bridge_deck_ground_y + bridge_y_offset;
+
     // Place floor blocks
     for (x, z) in bridge_area {
-        editor.set_block(floor_block, x, bridge_y_offset, z, None, None);
+        editor.set_block_absolute(floor_block, x, floor_y, z, None, None);
     }
 }

src/element_processing/highways.rs

@@ -2,7 +2,7 @@ use crate::args::Args;
 use crate::block_definitions::*;
 use crate::bresenham::bresenham_line;
 use crate::coordinate_system::cartesian::XZPoint;
-use crate::floodfill::flood_fill_area;
+use crate::floodfill_cache::FloodFillCache;
 use crate::osm_parser::{ProcessedElement, ProcessedWay};
 use crate::world_editor::WorldEditor;
 use std::collections::HashMap;
@@ -10,14 +10,24 @@ use std::collections::HashMap;
 /// Type alias for highway connectivity map
 pub type HighwayConnectivityMap = HashMap<(i32, i32), Vec<i32>>;
 
+/// Minimum terrain dip (in blocks) below max endpoint elevation to classify a bridge as valley-spanning
+const VALLEY_BRIDGE_THRESHOLD: i32 = 7;
+
 /// Generates highways with elevation support based on layer tags and connectivity analysis
 pub fn generate_highways(
     editor: &mut WorldEditor,
     element: &ProcessedElement,
     args: &Args,
     highway_connectivity: &HighwayConnectivityMap,
+    flood_fill_cache: &FloodFillCache,
 ) {
-    generate_highways_internal(editor, element, args, highway_connectivity);
+    generate_highways_internal(
+        editor,
+        element,
+        args,
+        highway_connectivity,
+        flood_fill_cache,
+    );
 }
 
 /// Build a connectivity map for highway endpoints to determine where slopes are needed.
@@ -66,6 +76,7 @@ fn generate_highways_internal(
     element: &ProcessedElement,
     args: &Args,
     highway_connectivity: &HashMap<(i32, i32), Vec<i32>>, // Maps node coordinates to list of layers that connect to this node
+    flood_fill_cache: &FloodFillCache,
 ) {
     if let Some(highway_type) = element.tags().get("highway") {
         if highway_type == "street_lamp" {
@@ -137,14 +148,9 @@ fn generate_highways_internal(
                 };
             }
 
-            // Fill the area using flood fill or by iterating through the nodes
-            let polygon_coords: Vec<(i32, i32)> = way
-                .nodes
-                .iter()
-                .map(|n: &crate::osm_parser::ProcessedNode| (n.x, n.z))
-                .collect();
+            // Fill the area using flood fill cache
             let filled_area: Vec<(i32, i32)> =
-                flood_fill_area(&polygon_coords, args.timeout.as_ref());
+                flood_fill_cache.get_or_compute(way, args.timeout.as_ref());
 
             for (x, z) in filled_area {
                 editor.set_block(surface_block, x, 0, z, None, None);
@@ -157,6 +163,11 @@ fn generate_highways_internal(
             let mut add_outline = false;
             let scale_factor = args.scale;
 
+            // Check if this is a bridge - bridges need special elevation handling
+            // to span across valleys instead of following terrain
+            // Accept any bridge tag value except "no" (e.g., "yes", "viaduct", "aqueduct", etc.)
+            let is_bridge = element.tags().get("bridge").is_some_and(|v| v != "no");
+
             // Parse the layer value for elevation calculation
             let layer_value = element
                 .tags()
@@ -246,6 +257,7 @@ fn generate_highways_internal(
             let base_elevation = layer_value * LAYER_HEIGHT_STEP;
 
             // Check if we need slopes at start and end
+            // This is used for overpasses that need ramps to ground-level roads
             let needs_start_slope =
                 should_add_slope_at_node(&way.nodes[0], layer_value, highway_connectivity);
             let needs_end_slope = should_add_slope_at_node(
@@ -254,10 +266,67 @@ fn generate_highways_internal(
                 highway_connectivity,
             );
 
-            // Calculate total way length for slope distribution
+            // Calculate total way length for slope distribution (needed before valley bridge check)
             let total_way_length = calculate_way_length(way);
 
-            // Check if this is a short isolated elevated segment - if so, treat as ground level
+            // For bridges: detect if this spans a valley by checking terrain profile
+            // A valley bridge has terrain that dips significantly below the endpoints
+            // Skip valley detection entirely if terrain is disabled (no valleys in flat terrain)
+            // Skip very short bridges (< 25 blocks) as they're unlikely to span significant valleys
+            let terrain_enabled = editor
+                .get_ground()
+                .map(|g| g.elevation_enabled)
+                .unwrap_or(false);
+
+            let (is_valley_bridge, bridge_deck_y) =
+                if is_bridge && terrain_enabled && way.nodes.len() >= 2 && total_way_length >= 25 {
+                    let start_node = &way.nodes[0];
+                    let end_node = &way.nodes[way.nodes.len() - 1];
+                    let start_y = editor.get_ground_level(start_node.x, start_node.z);
+                    let end_y = editor.get_ground_level(end_node.x, end_node.z);
+                    let max_endpoint_y = start_y.max(end_y);
+
+                    // Sample terrain at middle nodes only (excluding endpoints we already have)
+                    // This avoids redundant get_ground_level() calls
+                    let middle_nodes = &way.nodes[1..way.nodes.len().saturating_sub(1)];
+                    let sampled_min = if middle_nodes.is_empty() {
+                        // No middle nodes, just use endpoints
+                        start_y.min(end_y)
+                    } else {
+                        // Sample up to 3 middle points (5 total with endpoints) for performance
+                        // Valleys are wide terrain features, so sparse sampling is sufficient
+                        let sample_count = middle_nodes.len().min(3);
+                        let step = if sample_count > 1 {
+                            (middle_nodes.len() - 1) / (sample_count - 1)
+                        } else {
+                            1
+                        };
+
+                        middle_nodes
+                            .iter()
+                            .step_by(step.max(1))
+                            .map(|node| editor.get_ground_level(node.x, node.z))
+                            .min()
+                            .unwrap_or(max_endpoint_y)
+                    };
+
+                    // Include endpoint elevations in the minimum calculation
+                    let min_terrain_y = sampled_min.min(start_y).min(end_y);
+
+                    // If ANY sampled point along the bridge is significantly lower than the max endpoint,
+                    // treat as valley bridge
+                    let is_valley = min_terrain_y < max_endpoint_y - VALLEY_BRIDGE_THRESHOLD;
+
+                    if is_valley {
+                        (true, max_endpoint_y)
+                    } else {
+                        (false, 0)
+                    }
+                } else {
+                    (false, 0)
+                };
+
+            // Check if this is a short isolated elevated segment (layer > 0), if so, treat as ground level
             let is_short_isolated_elevated =
                 needs_start_slope && needs_end_slope && layer_value > 0 && total_way_length <= 35;
 
@@ -294,17 +363,28 @@ fn generate_highways_internal(
                     let gap_length: i32 = (5.0 * scale_factor).ceil() as i32;
 
                     for (point_index, (x, _, z)) in bresenham_points.iter().enumerate() {
-                        // Calculate Y elevation for this point based on slopes and layer
-                        let current_y = calculate_point_elevation(
-                            segment_index,
-                            point_index,
-                            segment_length,
-                            total_segments,
-                            effective_elevation,
-                            effective_start_slope,
-                            effective_end_slope,
-                            slope_length,
-                        );
+                        // Calculate Y elevation for this point
+                        // For valley bridges: use fixed deck height (max of endpoints) to stay level
+                        // For overpasses and regular roads: use terrain-relative elevation with slopes
+                        let (current_y, use_absolute_y) = if is_valley_bridge {
+                            // Valley bridge deck is level at the maximum endpoint elevation
+                            // Don't add base_elevation - the layer tag indicates it's above water/road,
+                            // not that it should be higher than the terrain endpoints
+                            (bridge_deck_y, true)
+                        } else {
+                            // Regular road or overpass: use terrain-relative calculation with ramps
+                            let y = calculate_point_elevation(
+                                segment_index,
+                                point_index,
+                                segment_length,
+                                total_segments,
+                                effective_elevation,
+                                effective_start_slope,
+                                effective_end_slope,
+                                slope_length,
+                            );
+                            (y, false)
+                        };
 
                         // Draw the road surface for the entire width
                         for dx in -block_range..=block_range {
@@ -320,12 +400,32 @@ fn generate_highways_internal(
                                     let is_horizontal: bool = (x2 - x1).abs() >= (z2 - z1).abs();
                                     if is_horizontal {
                                         if set_x % 2 < 1 {
-                                            editor.set_block(
-                                                WHITE_CONCRETE,
+                                            if use_absolute_y {
+                                                editor.set_block_absolute(
+                                                    WHITE_CONCRETE,
+                                                    set_x,
+                                                    current_y,
+                                                    set_z,
+                                                    Some(&[BLACK_CONCRETE]),
+                                                    None,
+                                                );
+                                            } else {
+                                                editor.set_block(
+                                                    WHITE_CONCRETE,
+                                                    set_x,
+                                                    current_y,
+                                                    set_z,
+                                                    Some(&[BLACK_CONCRETE]),
+                                                    None,
+                                                );
+                                            }
+                                        } else if use_absolute_y {
+                                            editor.set_block_absolute(
+                                                BLACK_CONCRETE,
                                                 set_x,
                                                 current_y,
                                                 set_z,
-                                                Some(&[BLACK_CONCRETE]),
+                                                None,
                                                 None,
                                             );
                                         } else {
@@ -339,12 +439,32 @@ fn generate_highways_internal(
                                             );
                                         }
                                     } else if set_z % 2 < 1 {
-                                        editor.set_block(
-                                            WHITE_CONCRETE,
+                                        if use_absolute_y {
+                                            editor.set_block_absolute(
+                                                WHITE_CONCRETE,
+                                                set_x,
+                                                current_y,
+                                                set_z,
+                                                Some(&[BLACK_CONCRETE]),
+                                                None,
+                                            );
+                                        } else {
+                                            editor.set_block(
+                                                WHITE_CONCRETE,
+                                                set_x,
+                                                current_y,
+                                                set_z,
+                                                Some(&[BLACK_CONCRETE]),
+                                                None,
+                                            );
+                                        }
+                                    } else if use_absolute_y {
+                                        editor.set_block_absolute(
+                                            BLACK_CONCRETE,
                                             set_x,
                                             current_y,
                                             set_z,
-                                            Some(&[BLACK_CONCRETE]),
+                                            None,
                                             None,
                                         );
                                     } else {
@@ -357,6 +477,15 @@ fn generate_highways_internal(
                                             None,
                                         );
                                     }
+                                } else if use_absolute_y {
+                                    editor.set_block_absolute(
+                                        block_type,
+                                        set_x,
+                                        current_y,
+                                        set_z,
+                                        None,
+                                        Some(&[BLACK_CONCRETE, WHITE_CONCRETE]),
+                                    );
                                 } else {
                                     editor.set_block(
                                         block_type,
@@ -368,30 +497,53 @@ fn generate_highways_internal(
                                     );
                                 }
 
-                                // Add stone brick foundation underneath elevated highways for thickness
-                                if effective_elevation > 0 && current_y > 0 {
+                                // Add stone brick foundation underneath elevated highways/bridges for thickness
+                                if (effective_elevation > 0 || use_absolute_y) && current_y > 0 {
                                     // Add 1 layer of stone bricks underneath the highway surface
-                                    editor.set_block(
-                                        STONE_BRICKS,
-                                        set_x,
-                                        current_y - 1,
-                                        set_z,
-                                        None,
-                                        None,
-                                    );
+                                    if use_absolute_y {
+                                        editor.set_block_absolute(
+                                            STONE_BRICKS,
+                                            set_x,
+                                            current_y - 1,
+                                            set_z,
+                                            None,
+                                            None,
+                                        );
+                                    } else {
+                                        editor.set_block(
+                                            STONE_BRICKS,
+                                            set_x,
+                                            current_y - 1,
+                                            set_z,
+                                            None,
+                                            None,
+                                        );
+                                    }
                                 }
 
-                                // Add support pillars for elevated highways
-                                if effective_elevation != 0 && current_y > 0 {
-                                    add_highway_support_pillar(
-                                        editor,
-                                        set_x,
-                                        current_y,
-                                        set_z,
-                                        dx,
-                                        dz,
-                                        block_range,
-                                    );
+                                // Add support pillars for elevated highways/bridges
+                                if (effective_elevation != 0 || use_absolute_y) && current_y > 0 {
+                                    if use_absolute_y {
+                                        add_highway_support_pillar_absolute(
+                                            editor,
+                                            set_x,
+                                            current_y,
+                                            set_z,
+                                            dx,
+                                            dz,
+                                            block_range,
+                                        );
+                                    } else {
+                                        add_highway_support_pillar(
+                                            editor,
+                                            set_x,
+                                            current_y,
+                                            set_z,
+                                            dx,
+                                            dz,
+                                            block_range,
+                                        );
+                                    }
                                 }
                             }
                         }
@@ -402,27 +554,49 @@ fn generate_highways_internal(
                             for dz in -block_range..=block_range {
                                 let outline_x = x - block_range - 1;
                                 let outline_z = z + dz;
-                                editor.set_block(
-                                    LIGHT_GRAY_CONCRETE,
-                                    outline_x,
-                                    current_y,
-                                    outline_z,
-                                    None,
-                                    None,
-                                );
+                                if use_absolute_y {
+                                    editor.set_block_absolute(
+                                        LIGHT_GRAY_CONCRETE,
+                                        outline_x,
+                                        current_y,
+                                        outline_z,
+                                        None,
+                                        None,
+                                    );
+                                } else {
+                                    editor.set_block(
+                                        LIGHT_GRAY_CONCRETE,
+                                        outline_x,
+                                        current_y,
+                                        outline_z,
+                                        None,
+                                        None,
+                                    );
+                                }
                             }
                             // Right outline
                             for dz in -block_range..=block_range {
                                 let outline_x = x + block_range + 1;
                                 let outline_z = z + dz;
-                                editor.set_block(
-                                    LIGHT_GRAY_CONCRETE,
-                                    outline_x,
-                                    current_y,
-                                    outline_z,
-                                    None,
-                                    None,
-                                );
+                                if use_absolute_y {
+                                    editor.set_block_absolute(
+                                        LIGHT_GRAY_CONCRETE,
+                                        outline_x,
+                                        current_y,
+                                        outline_z,
+                                        None,
+                                        None,
+                                    );
+                                } else {
+                                    editor.set_block(
+                                        LIGHT_GRAY_CONCRETE,
+                                        outline_x,
+                                        current_y,
+                                        outline_z,
+                                        None,
+                                        None,
+                                    );
+                                }
                             }
                         }
 
@@ -431,14 +605,25 @@ fn generate_highways_internal(
                             if stripe_length < dash_length {
                                 let stripe_x: i32 = *x;
                                 let stripe_z: i32 = *z;
-                                editor.set_block(
-                                    WHITE_CONCRETE,
-                                    stripe_x,
-                                    current_y,
-                                    stripe_z,
-                                    Some(&[BLACK_CONCRETE]),
-                                    None,
-                                );
+                                if use_absolute_y {
+                                    editor.set_block_absolute(
+                                        WHITE_CONCRETE,
+                                        stripe_x,
+                                        current_y,
+                                        stripe_z,
+                                        Some(&[BLACK_CONCRETE]),
+                                        None,
+                                    );
+                                } else {
+                                    editor.set_block(
+                                        WHITE_CONCRETE,
+                                        stripe_x,
+                                        current_y,
+                                        stripe_z,
+                                        Some(&[BLACK_CONCRETE]),
+                                        None,
+                                    );
+                                }
                             }
 
                             // Increment stripe_length and reset after completing a dash and gap
@@ -582,6 +767,46 @@ fn add_highway_support_pillar(
     }
 }
 
+/// Add support pillars for bridges using absolute Y coordinates
+/// Pillars extend from ground level up to the bridge deck
+fn add_highway_support_pillar_absolute(
+    editor: &mut WorldEditor,
+    x: i32,
+    bridge_deck_y: i32,
+    z: i32,
+    dx: i32,
+    dz: i32,
+    _block_range: i32, // Keep for future use
+) {
+    // Only add pillars at specific intervals and positions
+    if dx == 0 && dz == 0 && (x + z) % 8 == 0 {
+        // Get the actual ground level at this position
+        let ground_y = editor.get_ground_level(x, z);
+
+        // Add pillar from ground up to bridge deck
+        // Only if the bridge is actually above the ground
+        if bridge_deck_y > ground_y {
+            for y in (ground_y + 1)..bridge_deck_y {
+                editor.set_block_absolute(STONE_BRICKS, x, y, z, None, None);
+            }
+
+            // Add pillar base at ground level
+            for base_dx in -1..=1 {
+                for base_dz in -1..=1 {
+                    editor.set_block_absolute(
+                        STONE_BRICKS,
+                        x + base_dx,
+                        ground_y,
+                        z + base_dz,
+                        None,
+                        None,
+                    );
+                }
+            }
+        }
+    }
+}
+
 /// Generates a siding using stone brick slabs
 pub fn generate_siding(editor: &mut WorldEditor, element: &ProcessedWay) {
     let mut previous_node: Option<XZPoint> = None;

src/element_processing/landuse.rs

@@ -1,16 +1,26 @@
 use crate::args::Args;
 use crate::block_definitions::*;
+use crate::deterministic_rng::element_rng;
 use crate::element_processing::tree::Tree;
-use crate::floodfill::flood_fill_area;
+use crate::floodfill_cache::{BuildingFootprintBitmap, FloodFillCache};
 use crate::osm_parser::{ProcessedMemberRole, ProcessedRelation, ProcessedWay};
 use crate::world_editor::WorldEditor;
 use rand::Rng;
 
-pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args: &Args) {
+pub fn generate_landuse(
+    editor: &mut WorldEditor,
+    element: &ProcessedWay,
+    args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
+) {
     // Determine block type based on landuse tag
     let binding: String = "".to_string();
     let landuse_tag: &String = element.tags.get("landuse").unwrap_or(&binding);
 
+    // Use deterministic RNG seeded by element ID for consistent results across region boundaries
+    let mut rng = element_rng(element.id);
+
     let block_type = match landuse_tag.as_str() {
         "greenfield" | "meadow" | "grass" | "orchard" | "forest" => GRASS_BLOCK,
         "farmland" => FARMLAND,
@@ -22,13 +32,13 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
             if residential_tag == "rural" {
                 GRASS_BLOCK
             } else {
-                STONE_BRICKS
+                STONE_BRICKS // Placeholder, will be randomized per-block
             }
         }
-        "commercial" => SMOOTH_STONE,
+        "commercial" => SMOOTH_STONE, // Placeholder, will be randomized per-block
         "education" => POLISHED_ANDESITE,
         "religious" => POLISHED_ANDESITE,
-        "industrial" => COBBLESTONE,
+        "industrial" => STONE, // Placeholder, will be randomized per-block
         "military" => GRAY_CONCRETE,
         "railway" => GRAVEL,
         "landfill" => {
@@ -44,19 +54,56 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
         _ => GRASS_BLOCK,
     };
 
-    // Get the area of the landuse element
-    let polygon_coords: Vec<(i32, i32)> = element.nodes.iter().map(|n| (n.x, n.z)).collect();
-    let floor_area: Vec<(i32, i32)> = flood_fill_area(&polygon_coords, args.timeout.as_ref());
-
-    let mut rng: rand::prelude::ThreadRng = rand::thread_rng();
+    // Get the area of the landuse element using cache
+    let floor_area: Vec<(i32, i32)> =
+        flood_fill_cache.get_or_compute(element, args.timeout.as_ref());
 
     for (x, z) in floor_area {
-        if landuse_tag == "traffic_island" {
-            editor.set_block(block_type, x, 1, z, None, None);
-        } else if landuse_tag == "construction" || landuse_tag == "railway" {
-            editor.set_block(block_type, x, 0, z, None, Some(&[SPONGE]));
+        // Apply per-block randomness for certain landuse types
+        let actual_block = if landuse_tag == "residential" && block_type == STONE_BRICKS {
+            // Urban residential: mix of stone bricks, cracked stone bricks, stone, cobblestone
+            let random_value = rng.gen_range(0..100);
+            if random_value < 72 {
+                STONE_BRICKS
+            } else if random_value < 87 {
+                CRACKED_STONE_BRICKS
+            } else if random_value < 92 {
+                STONE
+            } else {
+                COBBLESTONE
+            }
+        } else if landuse_tag == "commercial" {
+            // Commercial: mix of smooth stone, stone, cobblestone, stone bricks
+            let random_value = rng.gen_range(0..100);
+            if random_value < 40 {
+                SMOOTH_STONE
+            } else if random_value < 70 {
+                STONE_BRICKS
+            } else if random_value < 90 {
+                STONE
+            } else {
+                COBBLESTONE
+            }
+        } else if landuse_tag == "industrial" {
+            // Industrial: primarily stone, with some stone bricks and smooth stone
+            let random_value = rng.gen_range(0..100);
+            if random_value < 70 {
+                STONE
+            } else if random_value < 90 {
+                STONE_BRICKS
+            } else {
+                SMOOTH_STONE
+            }
         } else {
-            editor.set_block(block_type, x, 0, z, None, None);
+            block_type
+        };
+
+        if landuse_tag == "traffic_island" {
+            editor.set_block(actual_block, x, 1, z, None, None);
+        } else if landuse_tag == "construction" || landuse_tag == "railway" {
+            editor.set_block(actual_block, x, 0, z, None, Some(&[SPONGE]));
+        } else {
+            editor.set_block(actual_block, x, 0, z, None, None);
         }
 
         // Add specific features for different landuse types
@@ -84,7 +131,7 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                             editor.set_block(RED_FLOWER, x, 1, z, None, None);
                         }
                     } else if random_choice < 33 {
-                        Tree::create(editor, (x, 1, z));
+                        Tree::create(editor, (x, 1, z), Some(building_footprints));
                     } else if random_choice < 35 {
                         editor.set_block(OAK_LEAVES, x, 1, z, None, None);
                     }
@@ -94,7 +141,7 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                 if editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK])) {
                     let random_choice: i32 = rng.gen_range(0..30);
                     if random_choice == 20 {
-                        Tree::create(editor, (x, 1, z));
+                        Tree::create(editor, (x, 1, z), Some(building_footprints));
                     } else if random_choice == 2 {
                         let flower_block: Block = match rng.gen_range(1..=5) {
                             1 => OAK_LEAVES,
@@ -105,7 +152,11 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                         };
                         editor.set_block(flower_block, x, 1, z, None, None);
                     } else if random_choice <= 12 {
-                        editor.set_block(GRASS, x, 1, z, None, None);
+                        if rng.gen_range(0..100) < 12 {
+                            editor.set_block(FERN, x, 1, z, None, None);
+                        } else {
+                            editor.set_block(GRASS, x, 1, z, None, None);
+                        }
                     }
                 }
             }
@@ -207,7 +258,8 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                 if editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK])) {
                     match rng.gen_range(0..200) {
                         0 => editor.set_block(OAK_LEAVES, x, 1, z, None, None),
-                        1..=170 => editor.set_block(GRASS, x, 1, z, None, None),
+                        1..=8 => editor.set_block(FERN, x, 1, z, None, None),
+                        9..=170 => editor.set_block(GRASS, x, 1, z, None, None),
                         _ => {}
                     }
                 }
@@ -216,7 +268,8 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                 if editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK])) {
                     match rng.gen_range(0..200) {
                         0 => editor.set_block(OAK_LEAVES, x, 1, z, None, None),
-                        1..=17 => editor.set_block(GRASS, x, 1, z, None, None),
+                        1..=2 => editor.set_block(FERN, x, 1, z, None, None),
+                        3..=17 => editor.set_block(GRASS, x, 1, z, None, None),
                         _ => {}
                     }
                 }
@@ -225,11 +278,13 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
                 if editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK])) {
                     let random_choice: i32 = rng.gen_range(0..1001);
                     if random_choice < 5 {
-                        Tree::create(editor, (x, 1, z));
+                        Tree::create(editor, (x, 1, z), Some(building_footprints));
                     } else if random_choice < 6 {
                         editor.set_block(RED_FLOWER, x, 1, z, None, None);
                     } else if random_choice < 9 {
                         editor.set_block(OAK_LEAVES, x, 1, z, None, None);
+                    } else if random_choice < 40 {
+                        editor.set_block(FERN, x, 1, z, None, None);
                     } else if random_choice < 800 {
                         editor.set_block(GRASS, x, 1, z, None, None);
                     }
@@ -237,11 +292,12 @@ pub fn generate_landuse(editor: &mut WorldEditor, element: &ProcessedWay, args:
             }
             "orchard" => {
                 if x % 18 == 0 && z % 10 == 0 {
-                    Tree::create(editor, (x, 1, z));
+                    Tree::create(editor, (x, 1, z), Some(building_footprints));
                 } else if editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK])) {
                     match rng.gen_range(0..100) {
                         0 => editor.set_block(OAK_LEAVES, x, 1, z, None, None),
-                        1..=20 => editor.set_block(GRASS, x, 1, z, None, None),
+                        1..=2 => editor.set_block(FERN, x, 1, z, None, None),
+                        3..=20 => editor.set_block(GRASS, x, 1, z, None, None),
                         _ => {}
                     }
                 }
@@ -275,12 +331,20 @@ pub fn generate_landuse_from_relation(
     editor: &mut WorldEditor,
     rel: &ProcessedRelation,
     args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
 ) {
     if rel.tags.contains_key("landuse") {
         // Generate individual ways with their original tags
         for member in &rel.members {
             if member.role == ProcessedMemberRole::Outer {
-                generate_landuse(editor, &member.way.clone(), args);
+                generate_landuse(
+                    editor,
+                    &member.way.clone(),
+                    args,
+                    flood_fill_cache,
+                    building_footprints,
+                );
             }
         }
 
@@ -302,7 +366,13 @@ pub fn generate_landuse_from_relation(
             };
 
             // Generate landuse area from combined way
-            generate_landuse(editor, &combined_way, args);
+            generate_landuse(
+                editor,
+                &combined_way,
+                args,
+                flood_fill_cache,
+                building_footprints,
+            );
         }
     }
 }

src/element_processing/leisure.rs

@@ -1,13 +1,20 @@
 use crate::args::Args;
 use crate::block_definitions::*;
 use crate::bresenham::bresenham_line;
+use crate::deterministic_rng::element_rng;
 use crate::element_processing::tree::Tree;
-use crate::floodfill::flood_fill_area;
+use crate::floodfill_cache::{BuildingFootprintBitmap, FloodFillCache};
 use crate::osm_parser::{ProcessedMemberRole, ProcessedRelation, ProcessedWay};
 use crate::world_editor::WorldEditor;
 use rand::Rng;
 
-pub fn generate_leisure(editor: &mut WorldEditor, element: &ProcessedWay, args: &Args) {
+pub fn generate_leisure(
+    editor: &mut WorldEditor,
+    element: &ProcessedWay,
+    args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
+) {
     if let Some(leisure_type) = element.tags.get("leisure") {
         let mut previous_node: Option<(i32, i32)> = None;
         let mut corner_addup: (i32, i32, i32) = (0, 0, 0);
@@ -74,15 +81,13 @@ pub fn generate_leisure(editor: &mut WorldEditor, element: &ProcessedWay, args:
             previous_node = Some((node.x, node.z));
         }
 
-        // Flood-fill the interior of the leisure area
+        // Flood-fill the interior of the leisure area using cache
         if corner_addup != (0, 0, 0) {
-            let polygon_coords: Vec<(i32, i32)> = element
-                .nodes
-                .iter()
-                .map(|n: &crate::osm_parser::ProcessedNode| (n.x, n.z))
-                .collect();
             let filled_area: Vec<(i32, i32)> =
-                flood_fill_area(&polygon_coords, args.timeout.as_ref());
+                flood_fill_cache.get_or_compute(element, args.timeout.as_ref());
+
+            // Use deterministic RNG seeded by element ID for consistent results across region boundaries
+            let mut rng = element_rng(element.id);
 
             for (x, z) in filled_area {
                 editor.set_block(block_type, x, 0, z, Some(&[GRASS_BLOCK]), None);
@@ -91,7 +96,6 @@ pub fn generate_leisure(editor: &mut WorldEditor, element: &ProcessedWay, args:
                 if matches!(leisure_type.as_str(), "park" | "garden" | "nature_reserve")
                     && editor.check_for_block(x, 0, z, Some(&[GRASS_BLOCK]))
                 {
-                    let mut rng: rand::prelude::ThreadRng = rand::thread_rng();
                     let random_choice: i32 = rng.gen_range(0..1000);
 
                     match random_choice {
@@ -115,7 +119,7 @@ pub fn generate_leisure(editor: &mut WorldEditor, element: &ProcessedWay, args:
                         }
                         105..120 => {
                             // Tree
-                            Tree::create(editor, (x, 1, z));
+                            Tree::create(editor, (x, 1, z), Some(building_footprints));
                         }
                         _ => {}
                     }
@@ -123,7 +127,6 @@ pub fn generate_leisure(editor: &mut WorldEditor, element: &ProcessedWay, args:
 
                 // Add playground or recreation ground features
                 if matches!(leisure_type.as_str(), "playground" | "recreation_ground") {
-                    let mut rng: rand::prelude::ThreadRng = rand::thread_rng();
                     let random_choice: i32 = rng.gen_range(0..5000);
 
                     match random_choice {
@@ -176,12 +179,20 @@ pub fn generate_leisure_from_relation(
     editor: &mut WorldEditor,
     rel: &ProcessedRelation,
     args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
 ) {
     if rel.tags.get("leisure") == Some(&"park".to_string()) {
         // First generate individual ways with their original tags
         for member in &rel.members {
             if member.role == ProcessedMemberRole::Outer {
-                generate_leisure(editor, &member.way, args);
+                generate_leisure(
+                    editor,
+                    &member.way,
+                    args,
+                    flood_fill_cache,
+                    building_footprints,
+                );
             }
         }
 
@@ -201,6 +212,12 @@ pub fn generate_leisure_from_relation(
         };
 
         // Generate leisure area from combined way
-        generate_leisure(editor, &combined_way, args);
+        generate_leisure(
+            editor,
+            &combined_way,
+            args,
+            flood_fill_cache,
+            building_footprints,
+        );
     }
 }

src/element_processing/natural.rs

@@ -1,20 +1,27 @@
 use crate::args::Args;
 use crate::block_definitions::*;
 use crate::bresenham::bresenham_line;
+use crate::deterministic_rng::element_rng;
 use crate::element_processing::tree::Tree;
-use crate::floodfill::flood_fill_area;
+use crate::floodfill_cache::{BuildingFootprintBitmap, FloodFillCache};
 use crate::osm_parser::{ProcessedElement, ProcessedMemberRole, ProcessedRelation, ProcessedWay};
 use crate::world_editor::WorldEditor;
 use rand::Rng;
 
-pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, args: &Args) {
+pub fn generate_natural(
+    editor: &mut WorldEditor,
+    element: &ProcessedElement,
+    args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
+) {
     if let Some(natural_type) = element.tags().get("natural") {
         if natural_type == "tree" {
             if let ProcessedElement::Node(node) = element {
                 let x: i32 = node.x;
                 let z: i32 = node.z;
 
-                Tree::create(editor, (x, 1, z));
+                Tree::create(editor, (x, 1, z), Some(building_footprints));
             }
         } else {
             let mut previous_node: Option<(i32, i32)> = None;
@@ -69,17 +76,13 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                 previous_node = Some((x, z));
             }
 
-            // If there are natural nodes, flood-fill the area
+            // If there are natural nodes, flood-fill the area using cache
             if corner_addup != (0, 0, 0) {
-                let polygon_coords: Vec<(i32, i32)> = way
-                    .nodes
-                    .iter()
-                    .map(|n: &crate::osm_parser::ProcessedNode| (n.x, n.z))
-                    .collect();
                 let filled_area: Vec<(i32, i32)> =
-                    flood_fill_area(&polygon_coords, args.timeout.as_ref());
+                    flood_fill_cache.get_or_compute(way, args.timeout.as_ref());
 
-                let mut rng: rand::prelude::ThreadRng = rand::thread_rng();
+                // Use deterministic RNG seeded by element ID for consistent results across region boundaries
+                let mut rng = element_rng(way.id);
 
                 for (x, z) in filled_area {
                     editor.set_block(block_type, x, 0, z, None, None);
@@ -132,7 +135,7 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                             }
                             let random_choice = rng.gen_range(0..500);
                             if random_choice == 0 {
-                                Tree::create(editor, (x, 1, z));
+                                Tree::create(editor, (x, 1, z), Some(building_footprints));
                             } else if random_choice == 1 {
                                 let flower_block = match rng.gen_range(1..=4) {
                                     1 => RED_FLOWER,
@@ -161,7 +164,7 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                             }
                             let random_choice: i32 = rng.gen_range(0..30);
                             if random_choice == 0 {
-                                Tree::create(editor, (x, 1, z));
+                                Tree::create(editor, (x, 1, z), Some(building_footprints));
                             } else if random_choice == 1 {
                                 let flower_block = match rng.gen_range(1..=4) {
                                     1 => RED_FLOWER,
@@ -220,7 +223,11 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                                         // TODO implement mangrove
                                         let random_choice: i32 = rng.gen_range(0..40);
                                         if random_choice == 0 {
-                                            Tree::create(editor, (x, 1, z));
+                                            Tree::create(
+                                                editor,
+                                                (x, 1, z),
+                                                Some(building_footprints),
+                                            );
                                         } else if random_choice < 35 {
                                             editor.set_block(GRASS, x, 1, z, None, None);
                                         }
@@ -304,6 +311,7 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                                                         Tree::create(
                                                             editor,
                                                             (cluster_x, 1, cluster_z),
+                                                            Some(building_footprints),
                                                         );
                                                     } else if vegetation_chance < 15 {
                                                         // 15% chance for grass
@@ -416,7 +424,7 @@ pub fn generate_natural(editor: &mut WorldEditor, element: &ProcessedElement, ar
                             let hill_chance = rng.gen_range(0..1000);
                             if hill_chance == 0 {
                                 // 0.1% chance for rare trees
-                                Tree::create(editor, (x, 1, z));
+                                Tree::create(editor, (x, 1, z), Some(building_footprints));
                             } else if hill_chance < 50 {
                                 // 5% chance for flowers
                                 let flower_block = match rng.gen_range(1..=4) {
@@ -448,12 +456,20 @@ pub fn generate_natural_from_relation(
     editor: &mut WorldEditor,
     rel: &ProcessedRelation,
     args: &Args,
+    flood_fill_cache: &FloodFillCache,
+    building_footprints: &BuildingFootprintBitmap,
 ) {
     if rel.tags.contains_key("natural") {
         // Generate individual ways with their original tags
         for member in &rel.members {
             if member.role == ProcessedMemberRole::Outer {
-                generate_natural(editor, &ProcessedElement::Way(member.way.clone()), args);
+                generate_natural(
+                    editor,
+                    &ProcessedElement::Way((*member.way).clone()),
+                    args,
+                    flood_fill_cache,
+                    building_footprints,
+                );
             }
         }
 
@@ -475,7 +491,13 @@ pub fn generate_natural_from_relation(
             };
 
             // Generate natural area from combined way
-            generate_natural(editor, &ProcessedElement::Way(combined_way), args);
+            generate_natural(
+                editor,
+                &ProcessedElement::Way(combined_way),
+                args,
+                flood_fill_cache,
+                building_footprints,
+            );
         }
     }
 }

src/element_processing/tree.rs

@@ -1,4 +1,6 @@
 use crate::block_definitions::*;
+use crate::deterministic_rng::coord_rng;
+use crate::floodfill_cache::BuildingFootprintBitmap;
 use crate::world_editor::WorldEditor;
 use rand::Rng;
 
@@ -107,7 +109,25 @@ pub struct Tree<'a> {
 }
 
 impl Tree<'_> {
-    pub fn create(editor: &mut WorldEditor, (x, y, z): Coord) {
+    /// Creates a tree at the specified coordinates.
+    ///
+    /// # Arguments
+    /// * `editor` - The world editor to place blocks
+    /// * `(x, y, z)` - The base coordinates for the tree
+    /// * `building_footprints` - Optional bitmap of (x, z) coordinates that are inside buildings.
+    ///   If provided, trees will not be placed at coordinates within this bitmap.
+    pub fn create(
+        editor: &mut WorldEditor,
+        (x, y, z): Coord,
+        building_footprints: Option<&BuildingFootprintBitmap>,
+    ) {
+        // Skip if this coordinate is inside a building
+        if let Some(footprints) = building_footprints {
+            if footprints.contains(x, z) {
+                return;
+            }
+        }
+
         let mut blacklist: Vec<Block> = Vec::new();
         blacklist.extend(Self::get_building_wall_blocks());
         blacklist.extend(Self::get_building_floor_blocks());
@@ -115,7 +135,9 @@ impl Tree<'_> {
         blacklist.extend(Self::get_functional_blocks());
         blacklist.push(WATER);
 
-        let mut rng = rand::thread_rng();
+        // Use deterministic RNG based on coordinates for consistent tree types across region boundaries
+        // The element_id of 0 is used as a salt for tree-specific randomness
+        let mut rng = coord_rng(x, z, 0);
 
         let tree = Self::get_tree(match rng.gen_range(1..=3) {
             1 => TreeType::Oak,

src/element_processing/water_areas.rs

@@ -1,6 +1,5 @@
 use geo::orient::{Direction, Orient};
 use geo::{Contains, Intersects, LineString, Point, Polygon, Rect};
-use std::time::Instant;
 
 use crate::clipping::clip_water_ring_to_bbox;
 use crate::{
@@ -15,15 +14,13 @@ pub fn generate_water_area_from_way(
     element: &ProcessedWay,
     _xzbbox: &XZBBox,
 ) {
-    let start_time = Instant::now();
-
     let outers = [element.nodes.clone()];
     if !verify_closed_rings(&outers) {
         println!("Skipping way {} due to invalid polygon", element.id);
         return;
     }
 
-    generate_water_areas(editor, &outers, &[], start_time);
+    generate_water_areas(editor, &outers, &[]);
 }
 
 pub fn generate_water_areas_from_relation(
@@ -31,8 +28,6 @@ pub fn generate_water_areas_from_relation(
     element: &ProcessedRelation,
     xzbbox: &XZBBox,
 ) {
-    let start_time = Instant::now();
-
     // Check if this is a water relation (either with water tag or natural=water)
     let is_water = element.tags.contains_key("water")
         || element
@@ -123,14 +118,13 @@ pub fn generate_water_areas_from_relation(
         return;
     }
 
-    generate_water_areas(editor, &outers, &inners, start_time);
+    generate_water_areas(editor, &outers, &inners);
 }
 
 fn generate_water_areas(
     editor: &mut WorldEditor,
     outers: &[Vec<ProcessedNode>],
     inners: &[Vec<ProcessedNode>],
-    start_time: Instant,
 ) {
     // Calculate polygon bounding box to limit fill area
     let mut poly_min_x = i32::MAX;
@@ -169,9 +163,7 @@ fn generate_water_areas(
         .map(|x| x.iter().map(|y| y.xz()).collect::<Vec<_>>())
         .collect();
 
-    inverse_floodfill(
-        min_x, min_z, max_x, max_z, outers_xz, inners_xz, editor, start_time,
-    );
+    inverse_floodfill(min_x, min_z, max_x, max_z, outers_xz, inners_xz, editor);
 }
 
 /// Merges way segments that share endpoints into closed rings.
@@ -308,7 +300,6 @@ fn inverse_floodfill(
     outers: Vec<Vec<XZPoint>>,
     inners: Vec<Vec<XZPoint>>,
     editor: &mut WorldEditor,
-    start_time: Instant,
 ) {
     // Convert to geo Polygons with normalized winding order
     let inners: Vec<_> = inners
@@ -341,14 +332,7 @@ fn inverse_floodfill(
         })
         .collect();
 
-    inverse_floodfill_recursive(
-        (min_x, min_z),
-        (max_x, max_z),
-        &outers,
-        &inners,
-        editor,
-        start_time,
-    );
+    inverse_floodfill_recursive((min_x, min_z), (max_x, max_z), &outers, &inners, editor);
 }
 
 fn inverse_floodfill_recursive(
@@ -357,12 +341,11 @@ fn inverse_floodfill_recursive(
     outers: &[Polygon],
     inners: &[Polygon],
     editor: &mut WorldEditor,
-    start_time: Instant,
 ) {
-    // Check if we've exceeded 25 seconds
-    if start_time.elapsed().as_secs() > 25 {
-        println!("Water area generation exceeded 25 seconds, continuing anyway");
-    }
+    // Check if we've exceeded 40 seconds
+    // if start_time.elapsed().as_secs() > 40 {
+    //     println!("Water area generation exceeded 40 seconds, continuing anyway");
+    // }
 
     const ITERATIVE_THRES: i64 = 10_000;
 
@@ -417,7 +400,6 @@ fn inverse_floodfill_recursive(
                 &outers_intersects,
                 &inners_intersects,
                 editor,
-                start_time,
             );
         }
     }

src/elevation_data.rs

@@ -2,12 +2,11 @@ use crate::coordinate_system::{geographic::LLBBox, transformation::geo_distance}
 #[cfg(feature = "gui")]
 use crate::telemetry::{send_log, LogLevel};
 use image::Rgb;
-use std::path::Path;
+use rayon::prelude::*;
+use std::path::{Path, PathBuf};
 
 /// Maximum Y coordinate in Minecraft (build height limit)
 const MAX_Y: i32 = 319;
-/// Scale factor for converting real elevation to Minecraft heights
-const BASE_HEIGHT_SCALE: f64 = 0.7;
 /// AWS S3 Terrarium tiles endpoint (no API key required)
 const AWS_TERRARIUM_URL: &str =
     "https://s3.amazonaws.com/elevation-tiles-prod/terrarium/{z}/{x}/{y}.png";
@@ -17,6 +16,8 @@ const TERRARIUM_OFFSET: f64 = 32768.0;
 const MIN_ZOOM: u8 = 10;
 /// Maximum zoom level for terrain tiles
 const MAX_ZOOM: u8 = 15;
+/// Maximum concurrent tile downloads to be respectful to AWS
+const MAX_CONCURRENT_DOWNLOADS: usize = 8;
 
 /// Holds processed elevation data and metadata
 #[derive(Clone)]
@@ -29,6 +30,11 @@ pub struct ElevationData {
     pub(crate) height: usize,
 }
 
+/// RGB image buffer type for elevation tiles
+type TileImage = image::ImageBuffer<Rgb<u8>, Vec<u8>>;
+/// Result type for tile download operations: ((tile_x, tile_y), image) or error
+type TileDownloadResult = Result<((u32, u32), TileImage), String>;
+
 /// Calculates appropriate zoom level for the given bounding box
 fn calculate_zoom_level(bbox: &LLBBox) -> u8 {
     let lat_diff: f64 = (bbox.max().lat() - bbox.min().lat()).abs();
@@ -53,21 +59,103 @@ fn download_tile(
     tile_y: u32,
     zoom: u8,
     tile_path: &Path,
-) -> Result<image::ImageBuffer<Rgb<u8>, Vec<u8>>, Box<dyn std::error::Error>> {
+) -> Result<image::ImageBuffer<Rgb<u8>, Vec<u8>>, String> {
     println!("Fetching tile x={tile_x},y={tile_y},z={zoom} from AWS Terrain Tiles");
     let url: String = AWS_TERRARIUM_URL
         .replace("{z}", &zoom.to_string())
         .replace("{x}", &tile_x.to_string())
         .replace("{y}", &tile_y.to_string());
 
-    let response: reqwest::blocking::Response = client.get(&url).send()?;
-    response.error_for_status_ref()?;
-    let bytes = response.bytes()?;
-    std::fs::write(tile_path, &bytes)?;
-    let img: image::DynamicImage = image::load_from_memory(&bytes)?;
+    let response = client.get(&url).send().map_err(|e| e.to_string())?;
+    response.error_for_status_ref().map_err(|e| e.to_string())?;
+    let bytes = response.bytes().map_err(|e| e.to_string())?;
+    std::fs::write(tile_path, &bytes).map_err(|e| e.to_string())?;
+    let img = image::load_from_memory(&bytes).map_err(|e| e.to_string())?;
     Ok(img.to_rgb8())
 }
 
+/// Fetches a tile from cache or downloads it if not available
+/// Note: In parallel execution, multiple threads may attempt to download the same tile
+/// if it's missing or corrupted. This is harmless (just wastes some bandwidth) as
+/// file writes are atomic at the OS level.
+fn fetch_or_load_tile(
+    client: &reqwest::blocking::Client,
+    tile_x: u32,
+    tile_y: u32,
+    zoom: u8,
+    tile_path: &Path,
+) -> Result<image::ImageBuffer<Rgb<u8>, Vec<u8>>, String> {
+    if tile_path.exists() {
+        // Check if the cached file has a reasonable size (PNG files should be at least a few KB)
+        let file_size = std::fs::metadata(tile_path).map(|m| m.len()).unwrap_or(0);
+
+        if file_size < 1000 {
+            eprintln!(
+                "Warning: Cached tile at {} appears to be too small ({} bytes). Refetching tile.",
+                tile_path.display(),
+                file_size
+            );
+            #[cfg(feature = "gui")]
+            send_log(
+                LogLevel::Warning,
+                "Cached tile appears too small, refetching.",
+            );
+
+            // Remove the potentially corrupted file
+            if let Err(e) = std::fs::remove_file(tile_path) {
+                eprintln!("Warning: Failed to remove corrupted tile file: {e}");
+                #[cfg(feature = "gui")]
+                send_log(
+                    LogLevel::Warning,
+                    "Failed to remove corrupted tile file during refetching.",
+                );
+            }
+
+            // Re-download the tile
+            return download_tile(client, tile_x, tile_y, zoom, tile_path);
+        }
+
+        // Try to load cached tile, but handle corruption gracefully
+        match image::open(tile_path) {
+            Ok(img) => {
+                println!(
+                    "Loading cached tile x={tile_x},y={tile_y},z={zoom} from {}",
+                    tile_path.display()
+                );
+                Ok(img.to_rgb8())
+            }
+            Err(e) => {
+                eprintln!(
+                    "Cached tile at {} is corrupted or invalid: {}. Re-downloading...",
+                    tile_path.display(),
+                    e
+                );
+                #[cfg(feature = "gui")]
+                send_log(
+                    LogLevel::Warning,
+                    "Cached tile is corrupted or invalid. Re-downloading...",
+                );
+
+                // Remove the corrupted file
+                if let Err(e) = std::fs::remove_file(tile_path) {
+                    eprintln!("Warning: Failed to remove corrupted tile file: {e}");
+                    #[cfg(feature = "gui")]
+                    send_log(
+                        LogLevel::Warning,
+                        "Failed to remove corrupted tile file during re-download.",
+                    );
+                }
+
+                // Re-download the tile
+                download_tile(client, tile_x, tile_y, zoom, tile_path)
+            }
+        }
+    } else {
+        // Download the tile for the first time
+        download_tile(client, tile_x, tile_y, zoom, tile_path)
+    }
+}
+
 pub fn fetch_elevation_data(
     bbox: &LLBBox,
     scale: f64,
@@ -91,101 +179,68 @@ pub fn fetch_elevation_data(
     let mut height_grid: Vec<Vec<f64>> = vec![vec![f64::NAN; grid_width]; grid_height];
     let mut extreme_values_found = Vec::new(); // Track extreme values for debugging
 
-    let client: reqwest::blocking::Client = reqwest::blocking::Client::new();
-
-    let tile_cache_dir = Path::new("./arnis-tile-cache");
+    let tile_cache_dir = PathBuf::from("./arnis-tile-cache");
     if !tile_cache_dir.exists() {
-        std::fs::create_dir_all(tile_cache_dir)?;
+        std::fs::create_dir_all(&tile_cache_dir)?;
     }
 
-    // Fetch and process each tile
-    for (tile_x, tile_y) in &tiles {
-        // Check if tile is already cached
-        let tile_path = tile_cache_dir.join(format!("z{zoom}_x{tile_x}_y{tile_y}.png"));
+    // Create a shared HTTP client for connection pooling
+    let client = reqwest::blocking::Client::new();
 
-        let rgb_img: image::ImageBuffer<Rgb<u8>, Vec<u8>> = if tile_path.exists() {
-            // Check if the cached file has a reasonable size (PNG files should be at least a few KB)
-            let file_size = match std::fs::metadata(&tile_path) {
-                Ok(metadata) => metadata.len(),
-                Err(_) => 0,
-            };
+    // Download tiles in parallel with limited concurrency to be respectful to AWS
+    let num_tiles = tiles.len();
+    println!(
+        "Downloading {num_tiles} elevation tiles (up to {MAX_CONCURRENT_DOWNLOADS} concurrent)..."
+    );
 
-            if file_size < 1000 {
-                eprintln!(
-                    "Warning: Cached tile at {} appears to be too small ({} bytes). Refetching tile.",
-                    tile_path.display(),
-                    file_size
+    // Use a custom thread pool to limit concurrent downloads
+    let thread_pool = rayon::ThreadPoolBuilder::new()
+        .num_threads(MAX_CONCURRENT_DOWNLOADS)
+        .build()
+        .map_err(|e| format!("Failed to create thread pool: {e}"))?;
+
+    let downloaded_tiles: Vec<TileDownloadResult> = thread_pool.install(|| {
+        tiles
+            .par_iter()
+            .map(|(tile_x, tile_y)| {
+                let tile_path = tile_cache_dir.join(format!("z{zoom}_x{tile_x}_y{tile_y}.png"));
+
+                let rgb_img = fetch_or_load_tile(&client, *tile_x, *tile_y, zoom, &tile_path)?;
+                Ok(((*tile_x, *tile_y), rgb_img))
+            })
+            .collect()
+    });
+
+    // Check for any download errors
+    let mut successful_tiles = Vec::new();
+    for result in downloaded_tiles {
+        match result {
+            Ok(tile_data) => successful_tiles.push(tile_data),
+            Err(e) => {
+                eprintln!("Warning: Failed to download tile: {e}");
+                #[cfg(feature = "gui")]
+                send_log(
+                    LogLevel::Warning,
+                    &format!("Failed to download elevation tile: {e}"),
                 );
-
-                // Remove the potentially corrupted file
-                if let Err(remove_err) = std::fs::remove_file(&tile_path) {
-                    eprintln!(
-                        "Warning: Failed to remove corrupted tile file: {}",
-                        remove_err
-                    );
-                    #[cfg(feature = "gui")]
-                    send_log(
-                        LogLevel::Warning,
-                        "Failed to remove corrupted tile file during refetching.",
-                    );
-                }
-
-                // Re-download the tile
-                download_tile(&client, *tile_x, *tile_y, zoom, &tile_path)?
-            } else {
-                println!(
-                    "Loading cached tile x={tile_x},y={tile_y},z={zoom} from {}",
-                    tile_path.display()
-                );
-
-                // Try to load cached tile, but handle corruption gracefully
-                match image::open(&tile_path) {
-                    Ok(img) => img.to_rgb8(),
-                    Err(e) => {
-                        eprintln!(
-                            "Cached tile at {} is corrupted or invalid: {}. Re-downloading...",
-                            tile_path.display(),
-                            e
-                        );
-                        #[cfg(feature = "gui")]
-                        send_log(
-                            LogLevel::Warning,
-                            "Cached tile is corrupted or invalid. Re-downloading...",
-                        );
-
-                        // Remove the corrupted file
-                        if let Err(remove_err) = std::fs::remove_file(&tile_path) {
-                            eprintln!(
-                                "Warning: Failed to remove corrupted tile file: {}",
-                                remove_err
-                            );
-                            #[cfg(feature = "gui")]
-                            send_log(
-                                LogLevel::Warning,
-                                "Failed to remove corrupted tile file during re-download.",
-                            );
-                        }
-
-                        // Re-download the tile
-                        download_tile(&client, *tile_x, *tile_y, zoom, &tile_path)?
-                    }
-                }
             }
-        } else {
-            // Download the tile for the first time
-            download_tile(&client, *tile_x, *tile_y, zoom, &tile_path)?
-        };
+        }
+    }
 
+    println!("Processing {} elevation tiles...", successful_tiles.len());
+
+    // Process tiles sequentially (writes to shared height_grid)
+    for ((tile_x, tile_y), rgb_img) in successful_tiles {
         // Only process pixels that fall within the requested bbox
         for (y, row) in rgb_img.rows().enumerate() {
             for (x, pixel) in row.enumerate() {
                 // Convert tile pixel coordinates back to geographic coordinates
-                let pixel_lng = ((*tile_x as f64 + x as f64 / 256.0) / (2.0_f64.powi(zoom as i32)))
+                let pixel_lng = ((tile_x as f64 + x as f64 / 256.0) / (2.0_f64.powi(zoom as i32)))
                     * 360.0
                     - 180.0;
                 let pixel_lat_rad = std::f64::consts::PI
                     * (1.0
-                        - 2.0 * (*tile_y as f64 + y as f64 / 256.0) / (2.0_f64.powi(zoom as i32)));
+                        - 2.0 * (tile_y as f64 + y as f64 / 256.0) / (2.0_f64.powi(zoom as i32)));
                 let pixel_lat = pixel_lat_rad.sinh().atan().to_degrees();
 
                 // Skip pixels outside the requested bounding box
@@ -261,20 +316,18 @@ pub fn fetch_elevation_data(
     // This smooths terrain proportionally while preserving more detail.
     let sigma: f64 = BASE_SIGMA_REF * (grid_size / BASE_GRID_REF).sqrt();
 
-    let blur_percentage: f64 = (sigma / grid_size) * 100.0;
-    eprintln!(
+    //let blur_percentage: f64 = (sigma / grid_size) * 100.0;
+    /*eprintln!(
         "Elevation blur: grid={}x{}, sigma={:.2}, blur_percentage={:.2}%",
         grid_width, grid_height, sigma, blur_percentage
-    );
-
-    /* eprintln!(
-        "Grid: {}x{}, Blur sigma: {:.2}",
-        grid_width, grid_height, sigma
-    ); */
+    );*/
 
     // Continue with the existing blur and conversion to Minecraft heights...
     let blurred_heights: Vec<Vec<f64>> = apply_gaussian_blur(&height_grid, sigma);
 
+    // Release raw height grid
+    drop(height_grid);
+
     let mut mc_heights: Vec<Vec<i32>> = Vec::with_capacity(blurred_heights.len());
 
     // Find min/max in raw data
@@ -298,7 +351,7 @@ pub fn fetch_elevation_data(
         }
     }
 
-    eprintln!("Height data range: {min_height} to {max_height} m");
+    //eprintln!("Height data range: {min_height} to {max_height} m");
     if extreme_low_count > 0 {
         eprintln!(
             "WARNING: Found {extreme_low_count} pixels with extremely low elevations (< -1000m)"
@@ -311,35 +364,58 @@ pub fn fetch_elevation_data(
     }
 
     let height_range: f64 = max_height - min_height;
-    // Apply scale factor to height scaling
-    let mut height_scale: f64 = BASE_HEIGHT_SCALE * scale.sqrt(); // sqrt to make height scaling less extreme
-    let mut scaled_range: f64 = height_range * height_scale;
 
-    // Adaptive scaling: ensure we don't exceed reasonable Y range
-    let available_y_range = (MAX_Y - ground_level) as f64;
-    let safety_margin = 0.9; // Use 90% of available range
-    let max_allowed_range = available_y_range * safety_margin;
+    // Realistic height scaling: 1 meter of real elevation = scale blocks in Minecraft
+    // At scale=1.0, 1 meter = 1 block (realistic 1:1 mapping)
+    // At scale=2.0, 1 meter = 2 blocks (exaggerated for larger worlds)
+    let ideal_scaled_range: f64 = height_range * scale;
 
-    if scaled_range > max_allowed_range {
-        let adjustment_factor = max_allowed_range / scaled_range;
-        height_scale *= adjustment_factor;
-        scaled_range = height_range * height_scale;
+    // Calculate available Y range in Minecraft (from ground_level to MAX_Y)
+    // Leave a buffer at the top for buildings, trees, and other structures
+    const TERRAIN_HEIGHT_BUFFER: i32 = 15;
+    let available_y_range: f64 = (MAX_Y - TERRAIN_HEIGHT_BUFFER - ground_level) as f64;
+
+    // Determine final height scale:
+    // - Use realistic 1:1 (times scale) if terrain fits within Minecraft limits
+    // - Only compress if the terrain would exceed the build height
+    let scaled_range: f64 = if ideal_scaled_range <= available_y_range {
+        // Terrain fits! Use realistic scaling
         eprintln!(
-            "Height range too large, applying scaling adjustment factor: {adjustment_factor:.3}"
+            "Realistic elevation: {:.1}m range fits in {} available blocks",
+            height_range, available_y_range as i32
         );
-        eprintln!("Adjusted scaled range: {scaled_range:.1} blocks");
-    }
+        ideal_scaled_range
+    } else {
+        // Terrain too tall, compress to fit within Minecraft limits
+        let compression_factor: f64 = available_y_range / height_range;
+        let compressed_range: f64 = height_range * compression_factor;
+        eprintln!(
+            "Elevation compressed: {:.1}m range -> {:.0} blocks ({:.2}:1 ratio, 1 block = {:.2}m)",
+            height_range,
+            compressed_range,
+            height_range / compressed_range,
+            compressed_range / height_range
+        );
+        compressed_range
+    };
 
     // Convert to scaled Minecraft Y coordinates
+    // Lowest real elevation maps to ground_level, highest maps to ground_level + scaled_range
     for row in blurred_heights {
         let mc_row: Vec<i32> = row
             .iter()
             .map(|&h| {
-                // Scale the height differences
-                let relative_height: f64 = (h - min_height) / height_range;
+                // Calculate relative position within the elevation range (0.0 to 1.0)
+                let relative_height: f64 = if height_range > 0.0 {
+                    (h - min_height) / height_range
+                } else {
+                    0.0
+                };
+                // Scale to Minecraft blocks and add to ground level
                 let scaled_height: f64 = relative_height * scaled_range;
-                // With terrain enabled, ground_level is used as the MIN_Y for terrain
-                ((ground_level as f64 + scaled_height).round() as i32).clamp(ground_level, MAX_Y)
+                // Clamp to valid Minecraft Y range (leave buffer at top for structures)
+                ((ground_level as f64 + scaled_height).round() as i32)
+                    .clamp(ground_level, MAX_Y - TERRAIN_HEIGHT_BUFFER)
             })
             .collect();
         mc_heights.push(mc_row);
@@ -353,7 +429,7 @@ pub fn fetch_elevation_data(
             max_block_height = max_block_height.max(height);
         }
     }
-    eprintln!("Minecraft height data range: {min_block_height} to {max_block_height} blocks");
+    //eprintln!("Minecraft height data range: {min_block_height} to {max_block_height} blocks");
 
     Ok(ElevationData {
         heights: mc_heights,
@@ -513,7 +589,7 @@ fn filter_elevation_outliers(height_grid: &mut [Vec<f64>]) {
     let min_reasonable = all_heights[p1_idx];
     let max_reasonable = all_heights[p99_idx];
 
-    eprintln!("Filtering outliers outside range: {min_reasonable:.1}m to {max_reasonable:.1}m");
+    //eprintln!("Filtering outliers outside range: {min_reasonable:.1}m to {max_reasonable:.1}m");
 
     let mut outliers_filtered = 0;
 
@@ -528,7 +604,7 @@ fn filter_elevation_outliers(height_grid: &mut [Vec<f64>]) {
     }
 
     if outliers_filtered > 0 {
-        eprintln!("Filtered {outliers_filtered} elevation outliers, interpolating replacements...");
+        //eprintln!("Filtered {outliers_filtered} elevation outliers, interpolating replacements...");
         // Re-run the NaN filling to interpolate the filtered values
         fill_nan_values(height_grid);
     }

src/floodfill_cache.rs

@@ -0,0 +1,338 @@
+//! Pre-computed flood fill cache for parallel polygon filling.
+//!
+//! This module provides a way to pre-compute all flood fill operations in parallel
+//! before the main element processing loop, then retrieve cached results during
+//! sequential processing.
+
+use crate::coordinate_system::cartesian::XZBBox;
+use crate::floodfill::flood_fill_area;
+use crate::osm_parser::{ProcessedElement, ProcessedMemberRole, ProcessedWay};
+use fnv::FnvHashMap;
+use rayon::prelude::*;
+use std::time::Duration;
+
+/// A memory-efficient bitmap for storing building footprint coordinates.
+///
+/// Instead of storing each coordinate individually (~24 bytes per entry in a HashSet),
+/// this uses 1 bit per coordinate in the world bounds, reducing memory usage by ~200x.
+///
+/// For a world of size W x H blocks, the bitmap uses only (W * H) / 8 bytes.
+pub struct BuildingFootprintBitmap {
+    /// The bitmap data, where each bit represents one (x, z) coordinate
+    bits: Vec<u8>,
+    /// Minimum x coordinate (offset for indexing)
+    min_x: i32,
+    /// Minimum z coordinate (offset for indexing)
+    min_z: i32,
+    /// Width of the world (max_x - min_x + 1)
+    width: usize,
+    /// Height of the world (max_z - min_z + 1)
+    height: usize,
+    /// Number of coordinates marked as building footprints
+    count: usize,
+}
+
+impl BuildingFootprintBitmap {
+    /// Creates a new empty bitmap covering the given world bounds.
+    pub fn new(xzbbox: &XZBBox) -> Self {
+        let min_x = xzbbox.min_x();
+        let min_z = xzbbox.min_z();
+        // Use i64 to avoid overflow when world spans more than i32::MAX in either dimension
+        let width = (i64::from(xzbbox.max_x()) - i64::from(min_x) + 1) as usize;
+        let height = (i64::from(xzbbox.max_z()) - i64::from(min_z) + 1) as usize;
+
+        // Calculate number of bytes needed (round up to nearest byte)
+        let total_bits = width
+            .checked_mul(height)
+            .expect("BuildingFootprintBitmap: world size too large (width * height overflowed)");
+        let num_bytes = total_bits.div_ceil(8);
+
+        Self {
+            bits: vec![0u8; num_bytes],
+            min_x,
+            min_z,
+            width,
+            height,
+            count: 0,
+        }
+    }
+
+    /// Converts (x, z) coordinate to bit index, returning None if out of bounds.
+    #[inline]
+    fn coord_to_index(&self, x: i32, z: i32) -> Option<usize> {
+        // Use i64 arithmetic to avoid overflow when coordinates span large ranges
+        let local_x = i64::from(x) - i64::from(self.min_x);
+        let local_z = i64::from(z) - i64::from(self.min_z);
+
+        if local_x < 0 || local_z < 0 {
+            return None;
+        }
+
+        let local_x = local_x as usize;
+        let local_z = local_z as usize;
+
+        if local_x >= self.width || local_z >= self.height {
+            return None;
+        }
+
+        // Safe: bounds checks above ensure this won't overflow (max = total_bits - 1)
+        Some(local_z * self.width + local_x)
+    }
+
+    /// Sets a coordinate as part of a building footprint.
+    #[inline]
+    pub fn set(&mut self, x: i32, z: i32) {
+        if let Some(bit_index) = self.coord_to_index(x, z) {
+            let byte_index = bit_index / 8;
+            let bit_offset = bit_index % 8;
+
+            // Safety: coord_to_index already validates bounds, so byte_index is always valid
+            let mask = 1u8 << bit_offset;
+            // Only increment count if bit wasn't already set
+            if self.bits[byte_index] & mask == 0 {
+                self.bits[byte_index] |= mask;
+                self.count += 1;
+            }
+        }
+    }
+
+    /// Checks if a coordinate is part of a building footprint.
+    #[inline]
+    pub fn contains(&self, x: i32, z: i32) -> bool {
+        if let Some(bit_index) = self.coord_to_index(x, z) {
+            let byte_index = bit_index / 8;
+            let bit_offset = bit_index % 8;
+
+            // Safety: coord_to_index already validates bounds, so byte_index is always valid
+            return (self.bits[byte_index] >> bit_offset) & 1 == 1;
+        }
+        false
+    }
+
+    /// Returns true if no coordinates are marked.
+    #[must_use]
+    #[allow(dead_code)] // Standard API method for collection-like types
+    pub fn is_empty(&self) -> bool {
+        self.count == 0
+    }
+}
+
+/// A cache of pre-computed flood fill results, keyed by element ID.
+pub struct FloodFillCache {
+    /// Cached results: element_id -> filled coordinates
+    way_cache: FnvHashMap<u64, Vec<(i32, i32)>>,
+}
+
+impl FloodFillCache {
+    /// Creates an empty cache.
+    pub fn new() -> Self {
+        Self {
+            way_cache: FnvHashMap::default(),
+        }
+    }
+
+    /// Pre-computes flood fills for all elements that need them.
+    ///
+    /// This runs in parallel using Rayon, taking advantage of multiple CPU cores.
+    pub fn precompute(elements: &[ProcessedElement], timeout: Option<&Duration>) -> Self {
+        // Collect all ways that need flood fill
+        let ways_needing_fill: Vec<&ProcessedWay> = elements
+            .iter()
+            .filter_map(|el| match el {
+                ProcessedElement::Way(way) => {
+                    if Self::way_needs_flood_fill(way) {
+                        Some(way)
+                    } else {
+                        None
+                    }
+                }
+                _ => None,
+            })
+            .collect();
+
+        // Compute all way flood fills in parallel
+        let way_results: Vec<(u64, Vec<(i32, i32)>)> = ways_needing_fill
+            .par_iter()
+            .map(|way| {
+                let polygon_coords: Vec<(i32, i32)> =
+                    way.nodes.iter().map(|n| (n.x, n.z)).collect();
+                let filled = flood_fill_area(&polygon_coords, timeout);
+                (way.id, filled)
+            })
+            .collect();
+
+        // Build the cache
+        let mut cache = Self::new();
+        for (id, filled) in way_results {
+            cache.way_cache.insert(id, filled);
+        }
+
+        cache
+    }
+
+    /// Gets cached flood fill result for a way, or computes it if not cached.
+    ///
+    /// Note: Combined ways created from relations (e.g., in `generate_natural_from_relation`)
+    /// will miss the cache and fall back to on-demand computation. This is by design,
+    /// these synthetic ways don't exist in the original element list and have relation IDs
+    /// rather than way IDs. The individual member ways are still cached.
+    pub fn get_or_compute(
+        &self,
+        way: &ProcessedWay,
+        timeout: Option<&Duration>,
+    ) -> Vec<(i32, i32)> {
+        if let Some(cached) = self.way_cache.get(&way.id) {
+            // Clone is intentional: each result is typically accessed once during
+            // sequential processing, so the cost is acceptable vs Arc complexity
+            cached.clone()
+        } else {
+            // Fallback: compute on demand for synthetic/combined ways from relations
+            let polygon_coords: Vec<(i32, i32)> = way.nodes.iter().map(|n| (n.x, n.z)).collect();
+            flood_fill_area(&polygon_coords, timeout)
+        }
+    }
+
+    /// Gets cached flood fill result for a ProcessedElement (Way only).
+    /// For Nodes/Relations, returns empty vec.
+    pub fn get_or_compute_element(
+        &self,
+        element: &ProcessedElement,
+        timeout: Option<&Duration>,
+    ) -> Vec<(i32, i32)> {
+        match element {
+            ProcessedElement::Way(way) => self.get_or_compute(way, timeout),
+            _ => Vec::new(),
+        }
+    }
+
+    /// Determines if a way element needs flood fill based on its tags.
+    ///
+    /// This checks for tag presence (not specific values) because:
+    /// - Only some values within each tag type actually use flood fill
+    /// - But caching extra results is harmless (small memory overhead)
+    /// - And avoids duplicating value-checking logic from processors
+    ///
+    /// Covered cases:
+    /// - building/building:part -> buildings::generate_buildings (includes bridge)
+    /// - landuse -> landuse::generate_landuse
+    /// - leisure -> leisure::generate_leisure
+    /// - amenity -> amenities::generate_amenities
+    /// - natural (except tree) -> natural::generate_natural
+    /// - highway with area=yes -> highways::generate_highways (area fill)
+    fn way_needs_flood_fill(way: &ProcessedWay) -> bool {
+        way.tags.contains_key("building")
+            || way.tags.contains_key("building:part")
+            || way.tags.contains_key("landuse")
+            || way.tags.contains_key("leisure")
+            || way.tags.contains_key("amenity")
+            || way
+                .tags
+                .get("natural")
+                .map(|v| v != "tree")
+                .unwrap_or(false)
+            // Highway areas (like pedestrian plazas) use flood fill when area=yes
+            || (way.tags.contains_key("highway")
+                && way.tags.get("area").map(|v| v == "yes").unwrap_or(false))
+    }
+
+    /// Collects all building footprint coordinates from the pre-computed cache.
+    ///
+    /// This should be called after precompute() and before elements are processed.
+    /// Returns a memory-efficient bitmap of all (x, z) coordinates that are part of buildings.
+    ///
+    /// The bitmap uses only 1 bit per coordinate in the world bounds, compared to ~24 bytes
+    /// per entry in a HashSet, reducing memory usage by ~200x for large worlds.
+    pub fn collect_building_footprints(
+        &self,
+        elements: &[ProcessedElement],
+        xzbbox: &XZBBox,
+    ) -> BuildingFootprintBitmap {
+        let mut footprints = BuildingFootprintBitmap::new(xzbbox);
+
+        for element in elements {
+            match element {
+                ProcessedElement::Way(way) => {
+                    if way.tags.contains_key("building") || way.tags.contains_key("building:part") {
+                        if let Some(cached) = self.way_cache.get(&way.id) {
+                            for &(x, z) in cached {
+                                footprints.set(x, z);
+                            }
+                        }
+                    }
+                }
+                ProcessedElement::Relation(rel) => {
+                    if rel.tags.contains_key("building") || rel.tags.contains_key("building:part") {
+                        for member in &rel.members {
+                            // Only treat outer members as building footprints.
+                            // Inner members represent courtyards/holes where trees can spawn.
+                            if member.role == ProcessedMemberRole::Outer {
+                                if let Some(cached) = self.way_cache.get(&member.way.id) {
+                                    for &(x, z) in cached {
+                                        footprints.set(x, z);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+
+        footprints
+    }
+
+    /// Removes a way's cached flood fill result, freeing memory.
+    ///
+    /// Call this after processing an element to release its cached data.
+    pub fn remove_way(&mut self, way_id: u64) {
+        self.way_cache.remove(&way_id);
+    }
+
+    /// Removes all cached flood fill results for ways in a relation.
+    ///
+    /// Relations contain multiple ways, so we need to remove all of them.
+    pub fn remove_relation_ways(&mut self, way_ids: &[u64]) {
+        for &id in way_ids {
+            self.way_cache.remove(&id);
+        }
+    }
+}
+
+impl Default for FloodFillCache {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Configures the global Rayon thread pool with a CPU usage cap.
+///
+/// Call this once at startup before any parallel operations.
+///
+/// # Arguments
+/// * `cpu_fraction` - Fraction of available cores to use (e.g., 0.9 for 90%).
+///   Values are clamped to the range [0.1, 1.0].
+pub fn configure_rayon_thread_pool(cpu_fraction: f64) {
+    // Clamp cpu_fraction to valid range
+    let cpu_fraction = cpu_fraction.clamp(0.1, 1.0);
+
+    let available_cores = std::thread::available_parallelism()
+        .map(|n| n.get())
+        .unwrap_or(4);
+
+    let target_threads = ((available_cores as f64) * cpu_fraction).floor() as usize;
+    let target_threads = target_threads.max(1); // At least 1 thread
+
+    // Only configure if we haven't already (this can only be called once)
+    match rayon::ThreadPoolBuilder::new()
+        .num_threads(target_threads)
+        .build_global()
+    {
+        Ok(()) => {
+            // Successfully configured (silent to avoid cluttering output)
+        }
+        Err(_) => {
+            // Thread pool already configured
+        }
+    }
+}

src/gui.rs

@@ -1,5 +1,5 @@
 use crate::args::Args;
-use crate::coordinate_system::cartesian::XZPoint;
+use crate::coordinate_system::cartesian::{XZBBox, XZPoint};
 use crate::coordinate_system::geographic::{LLBBox, LLPoint};
 use crate::coordinate_system::transformation::CoordTransformer;
 use crate::data_processing::{self, GenerationOptions};
@@ -74,6 +74,9 @@ fn get_area_name_for_bedrock(bbox: &LLBBox) -> String {
 }
 
 pub fn run_gui() {
+    // Configure thread pool with 90% CPU cap to keep system responsive
+    crate::floodfill_cache::configure_rayon_thread_pool(0.9);
+
     // Launch the UI
     println!("Launching UI...");
 
@@ -155,16 +158,20 @@ fn gui_select_world(generate_new: bool) -> Result<String, i32> {
 
     if generate_new {
         // Handle new world generation
-        if let Some(default_path) = &default_dir {
+        // Try Minecraft saves directory first, fall back to current directory
+        let target_path = if let Some(default_path) = &default_dir {
             if default_path.exists() {
-                // Call create_new_world and return the result
-                create_new_world(default_path).map_err(|_| 1) // Error code 1: Minecraft directory not found
+                default_path.clone()
             } else {
-                Err(1) // Error code 1: Minecraft directory not found
+                // Minecraft directory doesn't exist, use current directory
+                env::current_dir().unwrap_or_else(|_| PathBuf::from("."))
             }
         } else {
-            Err(1) // Error code 1: Minecraft directory not found
-        }
+            // No default directory configured, use current directory
+            env::current_dir().unwrap_or_else(|_| PathBuf::from("."))
+        };
+
+        create_new_world(&target_path).map_err(|_| 3) // Error code 3: Failed to create new world
     } else {
         // Handle existing world selection
         // Open the directory picker dialog
@@ -430,36 +437,20 @@ fn add_localized_world_name(world_path: PathBuf, bbox: &LLBBox) -> PathBuf {
     world_path
 }
 
-// Function to update player position in level.dat based on spawn point coordinates
-fn update_player_position(
+/// Calculates the default spawn point at X=1, Z=1 relative to the world origin.
+/// This is used when no spawn point is explicitly selected by the user.
+fn calculate_default_spawn(xzbbox: &XZBBox) -> (i32, i32) {
+    (xzbbox.min_x() + 1, xzbbox.min_z() + 1)
+}
+
+/// Sets the player spawn point in level.dat using Minecraft XZ coordinates.
+/// The Y coordinate is set to a temporary value (150) and will be updated
+/// after terrain generation by `update_player_spawn_y_after_generation`.
+fn set_player_spawn_in_level_dat(
     world_path: &str,
-    spawn_point: Option<(f64, f64)>,
-    bbox_text: String,
-    scale: f64,
+    spawn_x: i32,
+    spawn_z: i32,
 ) -> Result<(), String> {
-    use crate::coordinate_system::transformation::CoordTransformer;
-
-    let Some((lat, lng)) = spawn_point else {
-        return Ok(()); // No spawn point selected, exit early
-    };
-
-    // Parse geometrical point and bounding box
-    let llpoint =
-        LLPoint::new(lat, lng).map_err(|e| format!("Failed to parse spawn point:\n{e}"))?;
-    let llbbox = LLBBox::from_str(&bbox_text)
-        .map_err(|e| format!("Failed to parse bounding box for spawn point:\n{e}"))?;
-
-    // Check if spawn point is within the bbox
-    if !llbbox.contains(&llpoint) {
-        return Err("Spawn point is outside the selected area".to_string());
-    }
-
-    // Convert lat/lng to Minecraft coordinates
-    let (transformer, _) = CoordTransformer::llbbox_to_xzbbox(&llbbox, scale)
-        .map_err(|e| format!("Failed to build transformation on coordinate systems:\n{e}"))?;
-
-    let xzpoint = transformer.transform_point(llpoint);
-
     // Default y spawn position since terrain elevation cannot be determined yet
     let y = 150.0;
 
@@ -491,21 +482,24 @@ fn update_player_position(
     if let Value::Compound(ref mut root) = nbt_data {
         if let Some(Value::Compound(ref mut data)) = root.get_mut("Data") {
             // Set world spawn point
-            data.insert("SpawnX".to_string(), Value::Int(xzpoint.x));
+            data.insert("SpawnX".to_string(), Value::Int(spawn_x));
             data.insert("SpawnY".to_string(), Value::Int(y as i32));
-            data.insert("SpawnZ".to_string(), Value::Int(xzpoint.z));
+            data.insert("SpawnZ".to_string(), Value::Int(spawn_z));
 
-            // Update player position
+            // Update player position if Player compound exists
             if let Some(Value::Compound(ref mut player)) = data.get_mut("Player") {
                 if let Some(Value::List(ref mut pos)) = player.get_mut("Pos") {
-                    if let Value::Double(ref mut pos_x) = pos.get_mut(0).unwrap() {
-                        *pos_x = xzpoint.x as f64;
-                    }
-                    if let Value::Double(ref mut pos_y) = pos.get_mut(1).unwrap() {
-                        *pos_y = y;
-                    }
-                    if let Value::Double(ref mut pos_z) = pos.get_mut(2).unwrap() {
-                        *pos_z = xzpoint.z as f64;
+                    // Safely update position values with bounds checking
+                    if pos.len() >= 3 {
+                        if let Some(Value::Double(ref mut pos_x)) = pos.get_mut(0) {
+                            *pos_x = spawn_x as f64;
+                        }
+                        if let Some(Value::Double(ref mut pos_y)) = pos.get_mut(1) {
+                            *pos_y = y;
+                        }
+                        if let Some(Value::Double(ref mut pos_z)) = pos.get_mut(2) {
+                            *pos_z = spawn_z as f64;
+                        }
                     }
                 }
             }
@@ -537,19 +531,15 @@ fn update_player_position(
 }
 
 // Function to update player spawn Y coordinate based on terrain height after generation
+// This updates the spawn Y coordinate to be at terrain height + 3 blocks
 pub fn update_player_spawn_y_after_generation(
     world_path: &Path,
-    spawn_point: Option<(f64, f64)>,
     bbox_text: String,
     scale: f64,
     ground: &Ground,
 ) -> Result<(), String> {
     use crate::coordinate_system::transformation::CoordTransformer;
 
-    let Some((_lat, _lng)) = spawn_point else {
-        return Ok(()); // No spawn point selected, exit early
-    };
-
     // Read the current level.dat file to get existing spawn coordinates
     let level_path = PathBuf::from(world_path).join("level.dat");
     if !level_path.exists() {
@@ -618,7 +608,7 @@ pub fn update_player_spawn_y_after_generation(
         let relative_z = existing_spawn_z - xzbbox.min_z();
         let terrain_point = XZPoint::new(relative_x, relative_z);
 
-        ground.level(terrain_point) + 2
+        ground.level(terrain_point) + 3 // Add 3 blocks above terrain for safety
     } else {
         -61 // Default Y if no terrain
     };
@@ -632,8 +622,8 @@ pub fn update_player_spawn_y_after_generation(
             // Update player position - only Y coordinate
             if let Some(Value::Compound(ref mut player)) = data.get_mut("Player") {
                 if let Some(Value::List(ref mut pos)) = player.get_mut("Pos") {
-                    // Keep existing X and Z, only update Y
-                    if let Value::Double(ref mut pos_y) = pos.get_mut(1).unwrap() {
+                    // Safely update Y position with bounds checking
+                    if let Some(Value::Double(ref mut pos_y)) = pos.get_mut(1) {
                         *pos_y = spawn_y as f64;
                     }
                 }
@@ -794,7 +784,6 @@ fn gui_start_generation(
     selected_world: String,
     world_scale: f64,
     ground_level: i32,
-    floodfill_timeout: u64,
     terrain_enabled: bool,
     skip_osm_objects: bool,
     interior_enabled: bool,
@@ -814,50 +803,99 @@ fn gui_start_generation(
     // Send generation click telemetry
     telemetry::send_generation_click();
 
-    // If spawn point was chosen and the world is new, check and set the spawn point
+    // For new Java worlds, set the spawn point in level.dat
     // Only update player position for Java worlds - Bedrock worlds don't have a pre-existing
     // level.dat to modify (the spawn point will be set when the .mcworld is created)
-    if is_new_world && spawn_point.is_some() && world_format != "bedrock" {
-        // Verify the spawn point is within bounds
-        if let Some(coords) = spawn_point {
-            let llbbox = match LLBBox::from_str(&bbox_text) {
-                Ok(bbox) => bbox,
-                Err(e) => {
-                    let error_msg = format!("Failed to parse bounding box: {e}");
-                    eprintln!("{error_msg}");
-                    emit_gui_error(&error_msg);
-                    return Err(error_msg);
-                }
-            };
+    if is_new_world && world_format != "bedrock" {
+        let llbbox = match LLBBox::from_str(&bbox_text) {
+            Ok(bbox) => bbox,
+            Err(e) => {
+                let error_msg = format!("Failed to parse bounding box: {e}");
+                eprintln!("{error_msg}");
+                emit_gui_error(&error_msg);
+                return Err(error_msg);
+            }
+        };
 
+        let (transformer, xzbbox) = match CoordTransformer::llbbox_to_xzbbox(&llbbox, world_scale) {
+            Ok(result) => result,
+            Err(e) => {
+                let error_msg = format!("Failed to create coordinate transformer: {e}");
+                eprintln!("{error_msg}");
+                emit_gui_error(&error_msg);
+                return Err(error_msg);
+            }
+        };
+
+        let (spawn_x, spawn_z) = if let Some(coords) = spawn_point {
+            // User selected a spawn point - verify it's within bounds and convert to XZ
             let llpoint = LLPoint::new(coords.0, coords.1)
                 .map_err(|e| format!("Failed to parse spawn point: {e}"))?;
 
             if llbbox.contains(&llpoint) {
-                // Spawn point is valid, update the player position
-                update_player_position(
-                    &selected_world,
-                    spawn_point,
-                    bbox_text.clone(),
-                    world_scale,
-                )
-                .map_err(|e| format!("Failed to set spawn point: {e}"))?;
+                let xzpoint = transformer.transform_point(llpoint);
+                (xzpoint.x, xzpoint.z)
+            } else {
+                // Spawn point outside bounds, use default
+                calculate_default_spawn(&xzbbox)
             }
-        }
+        } else {
+            // No user-selected spawn point - use default at X=1, Z=1 relative to world origin
+            calculate_default_spawn(&xzbbox)
+        };
+
+        set_player_spawn_in_level_dat(&selected_world, spawn_x, spawn_z)
+            .map_err(|e| format!("Failed to set spawn point: {e}"))?;
     }
 
     tauri::async_runtime::spawn(async move {
         if let Err(e) = tokio::task::spawn_blocking(move || {
-            // Acquire session lock for the world directory before starting generation
             let world_path = PathBuf::from(&selected_world);
-            let _session_lock = match SessionLock::acquire(&world_path) {
-                Ok(lock) => lock,
-                Err(e) => {
-                    let error_msg = format!("Failed to acquire session lock: {e}");
+
+            // Determine world format from UI selection first (needed for session lock decision)
+            let world_format = if world_format == "bedrock" {
+                WorldFormat::BedrockMcWorld
+            } else {
+                WorldFormat::JavaAnvil
+            };
+
+            // Check available disk space before starting generation (minimum 3GB required)
+            const MIN_DISK_SPACE_BYTES: u64 = 3 * 1024 * 1024 * 1024; // 3 GB
+            let check_path = if world_format == WorldFormat::JavaAnvil {
+                world_path.clone()
+            } else {
+                // For Bedrock, check current directory where .mcworld will be created
+                std::env::current_dir().unwrap_or_else(|_| PathBuf::from("."))
+            };
+            match fs2::available_space(&check_path) {
+                Ok(available) if available < MIN_DISK_SPACE_BYTES => {
+                    let error_msg = "Not enough disk space available.".to_string();
                     eprintln!("{error_msg}");
                     emit_gui_error(&error_msg);
                     return Err(error_msg);
                 }
+                Err(e) => {
+                    // Log warning but don't block generation if we can't check space
+                    eprintln!("Warning: Could not check disk space: {e}");
+                }
+                _ => {} // Sufficient space available
+            }
+
+            // Acquire session lock for Java worlds only
+            // Session lock prevents Minecraft from having the world open during generation
+            // Bedrock worlds are generated as .mcworld files and don't need this lock
+            let _session_lock: Option<SessionLock> = if world_format == WorldFormat::JavaAnvil {
+                match SessionLock::acquire(&world_path) {
+                    Ok(lock) => Some(lock),
+                    Err(e) => {
+                        let error_msg = format!("Failed to acquire session lock: {e}");
+                        eprintln!("{error_msg}");
+                        emit_gui_error(&error_msg);
+                        return Err(error_msg);
+                    }
+                }
+            } else {
+                None
             };
 
             // Parse the bounding box from the text with proper error handling
@@ -871,13 +909,6 @@ fn gui_start_generation(
                 }
             };
 
-            // Determine world format from UI selection
-            let world_format = if world_format == "bedrock" {
-                WorldFormat::BedrockMcWorld
-            } else {
-                WorldFormat::JavaAnvil
-            };
-
             // Determine output path and level name based on format
             let (generation_path, level_name) = match world_format {
                 WorldFormat::JavaAnvil => {
@@ -902,6 +933,7 @@ fn gui_start_generation(
             };
 
             // Calculate MC spawn coordinates from lat/lng if spawn point was provided
+            // Otherwise, default to X=1, Z=1 (relative to xzbbox min coordinates)
             let mc_spawn_point: Option<(i32, i32)> = if let Some((lat, lng)) = spawn_point {
                 if let Ok(llpoint) = LLPoint::new(lat, lng) {
                     if let Ok((transformer, _)) =
@@ -916,7 +948,12 @@ fn gui_start_generation(
                     None
                 }
             } else {
-                None
+                // Default spawn point: X=1, Z=1 relative to world origin
+                if let Ok((_, xzbbox)) = CoordTransformer::llbbox_to_xzbbox(&bbox, world_scale) {
+                    Some(calculate_default_spawn(&xzbbox))
+                } else {
+                    None
+                }
             };
 
             // Create generation options
@@ -946,8 +983,7 @@ fn gui_start_generation(
                 roof: roof_enabled,
                 fillground: fillground_enabled,
                 debug: false,
-                timeout: Some(std::time::Duration::from_secs(floodfill_timeout)),
-                spawn_point,
+                timeout: Some(std::time::Duration::from_secs(40)),
             };
 
             // If skip_osm_objects is true (terrain-only mode), skip fetching and processing OSM data
@@ -963,17 +999,27 @@ fn gui_start_generation(
 
                 let _ = data_processing::generate_world_with_options(
                     parsed_elements,
-                    xzbbox,
+                    xzbbox.clone(),
                     args.bbox,
                     ground,
                     &args,
-                    generation_options,
+                    generation_options.clone(),
                 );
                 // Explicitly release session lock before showing Done message
                 // so Minecraft can open the world immediately
                 drop(_session_lock);
                 emit_gui_progress_update(100.0, "Done! World generation completed.");
                 println!("{}", "Done! World generation completed.".green().bold());
+
+                // Start map preview generation silently in background (Java only)
+                if world_format == WorldFormat::JavaAnvil {
+                    let preview_info = data_processing::MapPreviewInfo::new(
+                        generation_options.path.clone(),
+                        &xzbbox,
+                    );
+                    data_processing::start_map_preview_generation(preview_info);
+                }
+
                 return Ok(());
             }
 
@@ -1006,7 +1052,7 @@ fn gui_start_generation(
 
                     let _ = data_processing::generate_world_with_options(
                         parsed_elements,
-                        xzbbox,
+                        xzbbox.clone(),
                         args.bbox,
                         ground,
                         &args,
@@ -1017,13 +1063,22 @@ fn gui_start_generation(
                     drop(_session_lock);
                     emit_gui_progress_update(100.0, "Done! World generation completed.");
                     println!("{}", "Done! World generation completed.".green().bold());
+
+                    // Start map preview generation silently in background (Java only)
+                    if world_format == WorldFormat::JavaAnvil {
+                        let preview_info = data_processing::MapPreviewInfo::new(
+                            generation_options.path.clone(),
+                            &xzbbox,
+                        );
+                        data_processing::start_map_preview_generation(preview_info);
+                    }
+
                     Ok(())
                 }
                 Err(e) => {
-                    let error_msg = format!("Failed to fetch data: {e}");
-                    emit_gui_error(&error_msg);
+                    emit_gui_error(&e.to_string());
                     // Session lock will be automatically released when _session_lock goes out of scope
-                    Err(error_msg)
+                    Err(e.to_string())
                 }
             }
         })

src/gui/css/bbox.css

@@ -8,13 +8,9 @@ body,
   font-family: "Courier New", Courier, monospace;
 }
 
+/* Hide the BBOX coordinates display at bottom of map */
 #info-box {
-  position: absolute;
-  width: 100%;
-  height: auto;
-  bottom: 0;
-  border: 0 0 7px 0;
-  z-index: 10000;
+  display: none;
 }
 
 #coord-format {
@@ -351,7 +347,8 @@ body,
   background-position: -31px -2px;
 }
 
-.leaflet-draw-toolbar .leaflet-draw-edit-preview.disabled {
+.leaflet-draw-toolbar .leaflet-draw-edit-preview.disabled,
+.leaflet-draw-toolbar .leaflet-draw-edit-preview.editing-mode {
   opacity: 0.4;
   cursor: not-allowed;
   pointer-events: none;

src/gui/css/styles.css

@@ -32,9 +32,12 @@ p {
 
 .logo {
   height: 6em;
-  padding: 1.5em;
+  padding-top: 0.4em;
+  padding-bottom: 0.5em;
   will-change: filter;
   transition: 0.75s;
+  max-width: 950px;
+  max-height: 600px;
 }
 
 .logo.arnis:hover {
@@ -59,11 +62,11 @@ a:hover {
 
 .flex-container {
   display: flex;
-  gap: 20px;
+  gap: 15px;
   justify-content: center;
   align-items: stretch;
   margin-top: 5px;
-  min-height: 60vh;
+  min-height: 70vh;
 }
 
 .section {
@@ -75,34 +78,60 @@ a:hover {
 
 .map-box,
 .controls-box {
-  width: 45%;
-  background: #575757;
-  padding: 20px;
-  border-radius: 8px;
-  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
   display: flex;
   flex-direction: column;
 }
 
 .map-box {
-  min-height: 400px;
+  width: 63%;
+  min-height: 420px;
+  padding: 0;
+  overflow: hidden;
+  background: #575757;
+  border-radius: 8px;
+  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
+}
+
+.controls-box {
+  width: 32%;
+  background: transparent;
+  padding: 0;
+  border-radius: 0;
+  box-shadow: none;
 }
 
 .controls-content {
   display: flex;
   flex-direction: column;
   height: 100%;
+  justify-content: space-between;
 }
 
 .controls-box .progress-section {
-  margin-top: auto;
+  margin-top: 0;
+}
+
+.controls-top {
+  display: flex;
+  flex-direction: column;
+}
+
+.bbox-info-text {
+  font-size: 0.9em;
+  color: #ffffff;
+  display: block;
+  font-weight: bold;
+  min-height: 2.5em;
+  line-height: 1.25em;
+  margin-bottom: 5px;
 }
 
 .map-container {
-  border: 2px solid #e0e0e0;
+  border: none;
   border-radius: 8px;
   flex-grow: 1;
-  min-height: 300px;
+  width: 100%;
+  height: 100%;
 }
 
 .section h2 {
@@ -142,18 +171,26 @@ button:hover {
   margin-top: auto;
 }
 
-.progress-section h2 {
-  margin-bottom: 8px;
-  text-align: center;
+.progress-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
 }
 
 .progress-bar-container {
-  width: 100%;
+  flex: 1;
+  max-width: 80%;
   height: 20px;
   background-color: #e0e0e0;
   border-radius: 10px;
   overflow: hidden;
-  margin-top: 8px;
+}
+
+#progress-detail {
+  min-width: 40px;
+  text-align: right;
+  font-size: 0.9em;
+  color: #fff;
 }
 
 .progress-bar {
@@ -163,15 +200,6 @@ button:hover {
   transition: width 0.4s;
 }
 
-/* Left and right alignment for "Saving world..." text */
-.progress-status {
-  display: flex;
-  justify-content: space-between;
-  font-size: 0.9em;
-  margin-top: 8px;
-  color: #fff;
-}
-
 .footer {
   margin-top: 20px;
   text-align: center;
@@ -190,7 +218,7 @@ button:hover {
 @media (prefers-color-scheme: dark) {
   :root {
     color: #f6f6f6;
-    background-color: #2f2f2f;
+    background-color: #333333;
   }
 
   p {
@@ -233,6 +261,7 @@ button:hover {
   width: 100%;
   border-radius: 8px 8px 0 0 !important;
   margin-bottom: 0 !important;
+  margin-top: 0 !important;
   box-shadow: none !important;
 }
 
@@ -287,7 +316,7 @@ button:hover {
 /* Customization Settings */
 .modal {
   position: fixed;
-  z-index: 1000;
+  z-index: 20001;
   left: 0;
   top: 0;
   width: 100%;
@@ -300,7 +329,7 @@ button:hover {
 }
 
 .modal-content {
-  background-color: #797979;
+  background-color: #717171;
   padding: 20px;
   border: 1px solid #797979;
   border-radius: 10px;
@@ -420,6 +449,20 @@ button:hover {
   box-shadow: 0 0 5px #fecc44;
 }
 
+#save-path {
+  width: 100%;
+  padding: 5px;
+  border: 1px solid #fecc44;
+  border-radius: 4px;
+  font-size: 14px;
+}
+
+#save-path:focus {
+  outline: none;
+  border-color: #fecc44;
+  box-shadow: 0 0 5px #fecc44;
+}
+
 /* Settings Modal Layout */
 .settings-row {
   display: flex;
@@ -431,6 +474,75 @@ button:hover {
 .settings-row label {
   text-align: left;
   flex: 1;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+/* Tooltip icon (question mark in circle) */
+.tooltip-icon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 16px;
+  height: 16px;
+  border-radius: 50%;
+  background-color: rgba(254, 204, 68, 0.3);
+  color: #fecc44;
+  font-size: 11px;
+  font-weight: bold;
+  cursor: help;
+  position: relative;
+  flex-shrink: 0;
+}
+
+.tooltip-icon:hover {
+  background-color: rgba(254, 204, 68, 0.5);
+}
+
+/* Arnis-styled tooltip box */
+.tooltip-icon::after {
+  content: attr(data-tooltip);
+  position: absolute;
+  left: 50%;
+  bottom: calc(100% + 8px);
+  transform: translateX(-50%);
+  background-color: #2a2a2a;
+  color: #fecc44;
+  padding: 6px 14px;
+  border-radius: 6px;
+  font-size: 12px;
+  font-weight: normal;
+  white-space: nowrap;
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
+  border: 1px solid #fecc44;
+  opacity: 0;
+  visibility: hidden;
+  transition: opacity 0.2s ease, visibility 0.2s ease;
+  z-index: 1000;
+  pointer-events: none;
+}
+
+/* Tooltip arrow */
+.tooltip-icon::before {
+  content: '';
+  position: absolute;
+  left: 50%;
+  bottom: calc(100% + 2px);
+  transform: translateX(-50%);
+  border: 6px solid transparent;
+  border-top-color: #fecc44;
+  opacity: 0;
+  visibility: hidden;
+  transition: opacity 0.2s ease, visibility 0.2s ease;
+  z-index: 1001;
+  pointer-events: none;
+}
+
+.tooltip-icon:hover::after,
+.tooltip-icon:hover::before {
+  opacity: 1;
+  visibility: visible;
 }
 
 .settings-control {
@@ -606,9 +718,12 @@ button:hover {
   transition: background-color 0.3s, border-color 0.3s;
 }
 
-.settings-button .gear-icon::before {
-  content: "⚙️";
-  font-size: 18px;
+.settings-button svg {
+  stroke: white;
+  width: 22px;
+  height: 22px;
+  min-width: 22px;
+  min-height: 22px;
 }
 
 /* Logo Animation */

src/gui/index.html

@@ -20,60 +20,51 @@
     </div>
 
     <div class="flex-container">
-      <!-- Left Box: Map and BBox Input -->
-      <section class="section map-box" style="margin-bottom: 0; padding-bottom: 0;">
-        <h2 data-localize="select_location">Select Location</h2>
-        <span id="bbox-text" style="font-size: 1.0em; display: block; margin-top: -8px; margin-bottom: 3px;" data-localize="zoom_in_and_choose">
-          Zoom in and choose your area using the rectangle tool
-        </span>
-        <iframe src="maps.html" width="100%" height="300" class="map-container" title="Map Picker"></iframe>
-
-        <span id="bbox-info"
-          style="font-size: 0.75em; color: #7bd864; display: block; margin-bottom: 4px; font-weight: bold; min-height: 2em;"></span>
+      <!-- Left Box: Map -->
+      <section class="section map-box">
+        <iframe src="maps.html" width="100%" height="100%" class="map-container" title="Map Picker"></iframe>
       </section>
 
       <!-- Right Box: Directory Selection, Start Button, and Progress Bar -->
       <section class="section controls-box">
         <div class="controls-content">
-          <h2 data-localize="select_world">Select World</h2>
-
-          <!-- World Selection Container -->
-          <div class="world-selection-container">
-            <div class="tooltip" style="width: 100%;">
-              <button type="button" id="choose-world-btn" onclick="openWorldPicker()" class="choose-world-btn">
-                <span id="choose_world">Choose World</span>
-                <br>
-                <span id="selected-world" style="font-size: 0.8em; color: #fecc44; display: block; margin-top: 4px;" data-localize="no_world_selected">
-                  No world selected
-                </span>
-              </button>
+          <div class="controls-top">
+            <!-- World Selection Container -->
+            <div class="world-selection-container">
+              <div class="tooltip" style="width: 100%;">
+                <button type="button" id="choose-world-btn" onclick="openWorldPicker()" class="choose-world-btn">
+                  <span id="choose_world">Choose World</span>
+                  <br>
+                  <span id="selected-world" style="font-size: 0.8em; color: #fecc44; display: block; margin-top: 4px;" data-localize="no_world_selected">
+                    No world selected
+                  </span>
+                </button>
+              </div>
+              <!-- World Format Toggle -->
+              <div class="format-toggle-container">
+                <button type="button" id="format-java" class="format-toggle-btn format-active" onclick="setWorldFormat('java')">
+                  Java
+                </button>
+                <button type="button" id="format-bedrock" class="format-toggle-btn" onclick="setWorldFormat('bedrock')">
+                  Bedrock
+                </button>
+              </div>
             </div>
-            <!-- World Format Toggle -->
-            <div class="format-toggle-container">
-              <button type="button" id="format-java" class="format-toggle-btn format-active" onclick="setWorldFormat('java')">
-                Java
-              </button>
-              <button type="button" id="format-bedrock" class="format-toggle-btn" onclick="setWorldFormat('bedrock')">
-                Bedrock
+            
+            <div class="button-container">
+              <button type="button" id="start-button" class="start-button" onclick="startGeneration()" data-localize="start_generation">Start Generation</button>
+              <button type="button" class="settings-button" onclick="openSettings()" aria-label="Settings">
+                  <svg xmlns="http://www.w3.org/2000/svg" width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M12.22 2h-.44a2 2 0 0 0-2 2v.18a2 2 0 0 1-1 1.73l-.43.25a2 2 0 0 1-2 0l-.15-.08a2 2 0 0 0-2.73.73l-.22.38a2 2 0 0 0 .73 2.73l.15.1a2 2 0 0 1 1 1.72v.51a2 2 0 0 1-1 1.74l-.15.09a2 2 0 0 0-.73 2.73l.22.38a2 2 0 0 0 2.73.73l.15-.08a2 2 0 0 1 2 0l.43.25a2 2 0 0 1 1 1.73V20a2 2 0 0 0 2 2h.44a2 2 0 0 0 2-2v-.18a2 2 0 0 1 1-1.73l.43-.25a2 2 0 0 1 2 0l.15.08a2 2 0 0 0 2.73-.73l.22-.39a2 2 0 0 0-.73-2.73l-.15-.08a2 2 0 0 1-1-1.74v-.5a2 2 0 0 1 1-1.74l.15-.09a2 2 0 0 0 .73-2.73l-.22-.38a2 2 0 0 0-2.73-.73l-.15.08a2 2 0 0 1-2 0l-.43-.25a2 2 0 0 1-1-1.73V4a2 2 0 0 0-2-2z"></path><circle cx="12" cy="12" r="3"></circle></svg>
               </button>
             </div>
           </div>
-          
-          <div class="button-container">
-            <button type="button" id="start-button" class="start-button" onclick="startGeneration()" data-localize="start_generation">Start Generation</button>
-            <button type="button" class="settings-button" onclick="openSettings()">
-                <i class="gear-icon"></i>
-            </button>
-          </div>
-          <br><br>
 
           <div class="progress-section">
-            <h2 data-localize="progress">Progress</h2>
-            <div class="progress-bar-container">
-              <div class="progress-bar" id="progress-bar"></div>
-            </div>
-            <div class="progress-status">
-              <span id="progress-message"></span>
+            <span id="bbox-info" class="bbox-info-text" data-localize="select_area_prompt">Select an area on the map using the tools.</span>
+            <div class="progress-row">
+              <div class="progress-bar-container">
+                <div class="progress-bar" id="progress-bar"></div>
+              </div>
               <span id="progress-detail">0%</span>
             </div>
           </div>
@@ -100,7 +91,10 @@
 
         <!-- Generation Mode Dropdown -->
         <div class="settings-row">
-          <label for="generation-mode-select" data-localize="generation_mode">Generation Mode</label>
+          <label for="generation-mode-select">
+            <span data-localize="generation_mode">Generation Mode</span>
+            <span class="tooltip-icon" data-tooltip="Choose what to generate: buildings/roads with terrain, just objects, or terrain only">?</span>
+          </label>
           <div class="settings-control">
             <select id="generation-mode-select" name="generation-mode-select" class="generation-mode-dropdown">
               <option value="geo-terrain" data-localize="mode_geo_terrain">Objects + Terrain</option>
@@ -110,25 +104,34 @@
           </div>
         </div>
 
-        <!-- Interior Toggle Button -->
-        <div class="settings-row">
-          <label for="interior-toggle" data-localize="interior">Interior Generation</label>
-          <div class="settings-control">
-            <input type="checkbox" id="interior-toggle" name="interior-toggle" checked>
-          </div>
-        </div>
-
         <!-- Roof Toggle Button -->
         <div class="settings-row">
-          <label for="roof-toggle" data-localize="roof">Roof Generation</label>
+          <label for="roof-toggle">
+            <span data-localize="roof">Roof Generation</span>
+            <span class="tooltip-icon" data-tooltip="Generate roofs on buildings">?</span>
+          </label>
           <div class="settings-control">
             <input type="checkbox" id="roof-toggle" name="roof-toggle" checked>
           </div>
         </div>
 
+        <!-- Interior Toggle Button -->
+        <div class="settings-row">
+          <label for="interior-toggle">
+            <span data-localize="interior">Interior Generation</span>
+            <span class="tooltip-icon" data-tooltip="Generate interior details inside buildings">?</span>
+          </label>
+          <div class="settings-control">
+            <input type="checkbox" id="interior-toggle" name="interior-toggle">
+          </div>
+        </div>
+
         <!-- Fill ground Toggle Button -->
         <div class="settings-row">
-          <label for="fillground-toggle" data-localize="fillground">Fill Ground</label>
+          <label for="fillground-toggle">
+            <span data-localize="fillground">Fill Ground</span>
+            <span class="tooltip-icon" data-tooltip="Fill the ground below the surface">?</span>
+          </label>
           <div class="settings-control">
             <input type="checkbox" id="fillground-toggle" name="fillground-toggle">
           </div>
@@ -136,7 +139,10 @@
 
         <!-- World Scale Slider -->
         <div class="settings-row">
-          <label for="scale-value-slider" data-localize="world_scale">World Scale</label>
+          <label for="scale-value-slider">
+            <span data-localize="world_scale">World Scale</span>
+            <span class="tooltip-icon" data-tooltip="Scale factor for the generated world (1.0 = real-world scale)">?</span>
+          </label>
           <div class="settings-control">
             <input type="range" id="scale-value-slider" name="scale-value-slider" min="0.30" max="2.5" step="0.1" value="1">
             <span id="slider-value">1.00</span>
@@ -145,23 +151,21 @@
 
         <!-- Bounding Box Input -->
         <div class="settings-row">
-          <label for="bbox-coords" data-localize="custom_bounding_box">Custom Bounding Box</label>
+          <label for="bbox-coords">
+            <span data-localize="custom_bounding_box">Custom Bounding Box</span>
+            <span class="tooltip-icon" data-tooltip="Manually enter coordinates (lat,lng,lat,lng) or use map selection">?</span>
+          </label>
           <div class="settings-control">
             <input type="text" id="bbox-coords" name="bbox-coords" maxlength="55" placeholder="Format: lat,lng,lat,lng">
           </div>
         </div>
 
-        <!-- Floodfill Timeout Input -->
-        <div class="settings-row">
-          <label for="floodfill-timeout" data-localize="floodfill_timeout">Floodfill Timeout (sec)</label>
-          <div class="settings-control">
-            <input type="number" id="floodfill-timeout" name="floodfill-timeout" min="0" step="1" value="20" placeholder="Seconds">
-          </div>
-        </div>
-
         <!-- Map Theme Selector -->
         <div class="settings-row">
-          <label for="tile-theme-select" data-localize="map_theme">Map Theme</label>
+          <label for="tile-theme-select">
+            <span data-localize="map_theme">Map Theme</span>
+            <span class="tooltip-icon" data-tooltip="Visual style of the map picker">?</span>
+          </label>
           <div class="settings-control">
             <select id="tile-theme-select" name="tile-theme-select" class="theme-dropdown">
               <option value="osm">Standard</option>
@@ -175,7 +179,10 @@
 
         <!-- Language Selector -->
         <div class="settings-row">
-          <label for="language-select" data-localize="language">Language</label>
+          <label for="language-select">
+            <span data-localize="language">Language</span>
+            <span class="tooltip-icon" data-tooltip="Interface language">?</span>
+          </label>
           <div class="settings-control">
             <select id="language-select" name="language-select" class="language-dropdown">
               <option value="en">English</option>
@@ -199,7 +206,10 @@
 
         <!-- Telemetry Consent Toggle -->
         <div class="settings-row">
-          <label for="telemetry-toggle">Anonymous Crash Reports</label>
+          <label for="telemetry-toggle" style="white-space: nowrap;">
+            <span>Anonymous Crash Reports</span>
+            <span class="tooltip-icon" data-tooltip="Send anonymous crash data to help improve Arnis">?</span>
+          </label>
           <div class="settings-control">
             <input type="checkbox" id="telemetry-toggle" name="telemetry-toggle">
           </div>

src/gui/js/bbox.js

@@ -564,6 +564,7 @@ $(document).ready(function () {
     var worldOverlayEnabled = false;
     var worldPreviewAvailable = false;
     var sliderControl = null;
+    var worldOverlayHiddenForEdit = false; // Track if we hid the overlay for edit/delete mode
 
     // Create the opacity slider as a proper Leaflet control
     var SliderControl = L.Control.extend({
@@ -722,6 +723,32 @@ $(document).ready(function () {
         }
     }
 
+    // Temporarily hide the overlay (for edit/delete mode)
+    function hideWorldOverlayTemporarily() {
+        if (worldOverlay && worldOverlayEnabled) {
+            worldOverlayHiddenForEdit = true;
+            map.removeLayer(worldOverlay);
+        }
+        // Also visually disable the preview button during edit/delete mode
+        var btn = document.getElementById('world-preview-btn');
+        if (btn) {
+            btn.classList.add('editing-mode');
+        }
+    }
+
+    // Restore the overlay after edit/delete mode ends
+    function restoreWorldOverlay() {
+        if (worldOverlayHiddenForEdit && worldOverlay && worldOverlayEnabled) {
+            worldOverlay.addTo(map);
+            worldOverlayHiddenForEdit = false;
+        }
+        // Re-enable the preview button
+        var btn = document.getElementById('world-preview-btn');
+        if (btn) {
+            btn.classList.remove('editing-mode');
+        }
+    }
+
     // Listen for messages from parent window
     window.addEventListener('message', function(event) {
         if (event.data && event.data.type === 'changeTileTheme') {
@@ -899,6 +926,15 @@ $(document).ready(function () {
             });
         }
 
+        // If it's a rectangle, remove any existing rectangles first
+        if (e.layerType === 'rectangle') {
+            drawnItems.eachLayer(function(layer) {
+                if (layer instanceof L.Rectangle) {
+                    drawnItems.removeLayer(layer);
+                }
+            });
+        }
+
         // Check if it's a rectangle and set proper styles before adding it to the layer
         if (e.layerType === 'rectangle') {
             e.layer.setStyle({
@@ -990,6 +1026,23 @@ $(document).ready(function () {
         map.fitBounds(bounds.getBounds());
     });
 
+    // Hide world preview overlay when entering edit or delete mode
+    map.on('draw:editstart', function() {
+        hideWorldOverlayTemporarily();
+    });
+
+    map.on('draw:deletestart', function() {
+        hideWorldOverlayTemporarily();
+    });
+
+    // Restore world preview overlay when exiting edit or delete mode
+    map.on('draw:editstop', function() {
+        restoreWorldOverlay();
+    });
+
+    map.on('draw:deletestop', function() {
+        restoreWorldOverlay();
+    });
     function display() {
         $('#boxbounds').text(formatBounds(bounds.getBounds(), '4326'));
         $('#boxboundsmerc').text(formatBounds(bounds.getBounds(), currentproj));

src/gui/js/main.js

@@ -12,6 +12,25 @@ if (window.__TAURI__) {
 
 const DEFAULT_LOCALE_PATH = `./locales/en.json`;
 
+// Track current bbox-info localization key for language changes
+let currentBboxInfoKey = "select_area_prompt";
+let currentBboxInfoColor = "#ffffff";
+
+// Helper function to set bbox-info text and track it for language changes
+async function setBboxInfo(bboxInfoElement, localizationKey, color) {
+  currentBboxInfoKey = localizationKey;
+  currentBboxInfoColor = color;
+  
+  // Ensure localization is available
+  let localization = window.localization;
+  if (!localization) {
+    localization = await getLocalization();
+  }
+  
+  localizeElement(localization, { element: bboxInfoElement }, localizationKey);
+  bboxInfoElement.style.color = color;
+}
+
 // Initialize elements and start the demo progress
 window.addEventListener("DOMContentLoaded", async () => {
   registerMessageEvent();
@@ -66,7 +85,7 @@ async function localizeElement(json, elementObject, localizedStringKey) {
   const attribute = localizedStringKey.startsWith("placeholder_") ? "placeholder" : "textContent";
 
   if (element) {
-    if (localizedStringKey in json) {
+    if (json && localizedStringKey in json) {
       element[attribute] = json[localizedStringKey];
     } else {
       // Fallback to default (English) string
@@ -78,20 +97,15 @@ async function localizeElement(json, elementObject, localizedStringKey) {
 
 async function applyLocalization(localization) {
   const localizationElements = {
-    "h2[data-localize='select_location']": "select_location",
-    "#bbox-text": "zoom_in_and_choose",
-    "h2[data-localize='select_world']": "select_world",
     "span[id='choose_world']": "choose_world",
     "#selected-world": "no_world_selected",
     "#start-button": "start_generation",
-    "h2[data-localize='progress']": "progress",
     "h2[data-localize='choose_world_modal_title']": "choose_world_modal_title",
     "button[data-localize='select_existing_world']": "select_existing_world",
     "button[data-localize='generate_new_world']": "generate_new_world",
     "h2[data-localize='customization_settings']": "customization_settings",
     "label[data-localize='world_scale']": "world_scale",
     "label[data-localize='custom_bounding_box']": "custom_bounding_box",
-    "label[data-localize='floodfill_timeout']": "floodfill_timeout",
     // DEPRECATED: Ground level localization removed
     // "label[data-localize='ground_level']": "ground_level",
     "label[data-localize='language']": "language",
@@ -110,7 +124,6 @@ async function applyLocalization(localization) {
 
     // Placeholder strings
     "input[id='bbox-coords']": "placeholder_bbox",
-    "input[id='floodfill-timeout']": "placeholder_floodfill",
     // DEPRECATED: Ground level placeholder removed
     // "input[id='ground-level']": "placeholder_ground"
   };
@@ -119,6 +132,13 @@ async function applyLocalization(localization) {
     localizeElement(localization, { selector: selector }, localizationElements[selector]);
   }
 
+  // Re-apply current bbox-info text with new language
+  const bboxInfo = document.getElementById("bbox-info");
+  if (bboxInfo && currentBboxInfoKey) {
+    localizeElement(localization, { element: bboxInfo }, currentBboxInfoKey);
+    bboxInfo.style.color = currentBboxInfoColor;
+  }
+
   // Update error messages
   window.localization = localization;
 }
@@ -167,7 +187,7 @@ async function checkForUpdates() {
       updateMessage.style.textDecoration = "none";
 
       localizeElement(window.localization, { element: updateMessage }, "new_version_available");
-      footer.style.marginTop = "15px";
+      footer.style.marginTop = "10px";
       footer.appendChild(updateMessage);
     }
   } catch (error) {
@@ -190,7 +210,7 @@ function registerMessageEvent() {
 // Function to set up the progress bar listener
 function setupProgressListener() {
   const progressBar = document.getElementById("progress-bar");
-  const progressMessage = document.getElementById("progress-message");
+  const bboxInfo = document.getElementById("bbox-info");
   const progressDetail = document.getElementById("progress-detail");
 
   window.__TAURI__.event.listen("progress-update", (event) => {
@@ -202,16 +222,16 @@ function setupProgressListener() {
     }
 
     if (message != "") {
-      progressMessage.textContent = message;
+      bboxInfo.textContent = message;
 
       if (message.startsWith("Error!")) {
-        progressMessage.style.color = "#fa7878";
+        bboxInfo.style.color = "#fa7878";
         generationButtonEnabled = true;
       } else if (message.startsWith("Done!")) {
-        progressMessage.style.color = "#7bd864";
+        bboxInfo.style.color = "#7bd864";
         generationButtonEnabled = true;
       } else {
-        progressMessage.style.color = "";
+        bboxInfo.style.color = "#ececec";
       }
     }
   });
@@ -252,6 +272,20 @@ function initSettings() {
     settingsModal.style.display = "none";
   }
 
+  // Close settings and license modals on escape key
+  document.addEventListener("keydown", (event) => {
+    if (event.key === "Escape") {
+      if (settingsModal.style.display === "flex") {
+        closeSettings();
+      }
+      
+      const licenseModal = document.getElementById("license-modal");
+      if (licenseModal && licenseModal.style.display === "flex") {
+        closeLicense();
+      }
+    }
+  });
+
   window.openSettings = openSettings;
   window.closeSettings = closeSettings;
 
@@ -513,11 +547,12 @@ function handleBboxInput() {
       
       // Clear the info text only if no map selection exists
       if (!mapSelectedBBox) {
-        bboxInfo.textContent = "";
-        bboxInfo.style.color = "";
+        setBboxInfo(bboxInfo, "select_area_prompt", "#ffffff");
       } else {
-        // Restore map selection display
-        displayBboxInfoText(mapSelectedBBox);
+        // Restore map selection info display but don't update input field
+        const [lng1, lat1, lng2, lat2] = mapSelectedBBox.split(" ").map(Number);
+        const selectedSize = calculateBBoxSize(lng1, lat1, lng2, lat2);
+        displayBboxSizeStatus(bboxInfo, selectedSize);
       }
       return;
     }
@@ -553,8 +588,7 @@ function handleBboxInput() {
         // Update the info text and mark custom input as valid
         customBBoxValid = true;
         selectedBBox = bboxText.replace(/,/g, ' '); // Convert to space format for consistency
-        localizeElement(window.localization, { element: bboxInfo }, "custom_selection_confirmed");
-        bboxInfo.style.color = "#7bd864";
+        setBboxInfo(bboxInfo, "custom_selection_confirmed", "#7bd864");
       } else {
         // Valid numbers but invalid order or range
         customBBoxValid = false;
@@ -564,8 +598,7 @@ function handleBboxInput() {
         } else {
           selectedBBox = mapSelectedBBox;
         }
-        localizeElement(window.localization, { element: bboxInfo }, "error_coordinates_out_of_range");
-        bboxInfo.style.color = "#fecc44";
+        setBboxInfo(bboxInfo, "error_coordinates_out_of_range", "#fecc44");
       }
     } else {
       // Input doesn't match the required format
@@ -576,8 +609,7 @@ function handleBboxInput() {
       } else {
         selectedBBox = mapSelectedBBox;
       }
-      localizeElement(window.localization, { element: bboxInfo }, "invalid_format");
-      bboxInfo.style.color = "#fecc44";
+      setBboxInfo(bboxInfo, "invalid_format", "#fecc44");
     }
   });
 }
@@ -626,6 +658,21 @@ let selectedBBox = "";
 let mapSelectedBBox = "";  // Tracks bbox from map selection
 let customBBoxValid = false;  // Tracks if custom input is valid
 
+/**
+ * Displays the appropriate bbox size status message based on area thresholds
+ * @param {HTMLElement} bboxInfo - The element to display the message in
+ * @param {number} selectedSize - The calculated bbox area in square meters
+ */
+function displayBboxSizeStatus(bboxInfo, selectedSize) {
+  if (selectedSize > threshold2) {
+    setBboxInfo(bboxInfo, "area_too_large", "#fa7878");
+  } else if (selectedSize > threshold1) {
+    setBboxInfo(bboxInfo, "area_extensive", "#fecc44");
+  } else {
+    setBboxInfo(bboxInfo, "selection_confirmed", "#7bd864");
+  }
+}
+
 // Function to handle incoming bbox data
 function displayBboxInfoText(bboxText) {
   let [lng1, lat1, lng2, lat2] = bboxText.split(" ").map(Number);
@@ -640,10 +687,12 @@ function displayBboxInfoText(bboxText) {
   customBBoxValid = false;
 
   const bboxInfo = document.getElementById("bbox-info");
+  const bboxCoordsInput = document.getElementById("bbox-coords");
 
   // Reset the info text if the bbox is 0,0,0,0
   if (lng1 === 0 && lat1 === 0 && lng2 === 0 && lat2 === 0) {
-    bboxInfo.textContent = "";
+    setBboxInfo(bboxInfo, "select_area_prompt", "#ffffff");
+    bboxCoordsInput.value = "";
     mapSelectedBBox = "";
     if (!customBBoxValid) {
       selectedBBox = "";
@@ -651,19 +700,13 @@ function displayBboxInfoText(bboxText) {
     return;
   }
 
+  // Update the custom bbox input with the map selection (comma-separated format)
+  bboxCoordsInput.value = `${lng1},${lat1},${lng2},${lat2}`;
+
   // Calculate the size of the selected bbox
   const selectedSize = calculateBBoxSize(lng1, lat1, lng2, lat2);
 
-  if (selectedSize > threshold2) {
-    localizeElement(window.localization, { element: bboxInfo }, "area_too_large");
-    bboxInfo.style.color = "#fa7878";
-  } else if (selectedSize > threshold1) {
-    localizeElement(window.localization, { element: bboxInfo }, "area_extensive");
-    bboxInfo.style.color = "#fecc44";
-  } else {
-    localizeElement(window.localization, { element: bboxInfo }, "selection_confirmed");
-    bboxInfo.style.color = "#7bd864";
-  }
+  displayBboxSizeStatus(bboxInfo, selectedSize);
 }
 
 let worldPath = "";
@@ -754,8 +797,7 @@ async function startGeneration() {
 
     if (!selectedBBox || selectedBBox == "0.000000 0.000000 0.000000 0.000000") {
       const bboxInfo = document.getElementById('bbox-info');
-      localizeElement(window.localization, { element: bboxInfo }, "select_location_first");
-      bboxInfo.style.color = "#fa7878";
+      setBboxInfo(bboxInfo, "select_location_first", "#fa7878");
       return;
     }
 
@@ -791,14 +833,12 @@ async function startGeneration() {
     var roof = document.getElementById("roof-toggle").checked;
     var fill_ground = document.getElementById("fillground-toggle").checked;
     var scale = parseFloat(document.getElementById("scale-value-slider").value);
-    var floodfill_timeout = parseInt(document.getElementById("floodfill-timeout").value, 10);
     // var ground_level = parseInt(document.getElementById("ground-level").value, 10);
     // DEPRECATED: Ground level input removed from UI
     var ground_level = -62;
 
-    // Validate floodfill_timeout and ground_level
-    floodfill_timeout = isNaN(floodfill_timeout) || floodfill_timeout < 0 ? 20 : floodfill_timeout;
-    ground_level = isNaN(ground_level) || ground_level < -62 ? 20 : ground_level;
+    // Validate ground_level
+    ground_level = isNaN(ground_level) || ground_level < -62 ? -62 : ground_level;
 
     // Get telemetry consent (defaults to false if not set)
     const telemetryConsent = window.getTelemetryConsent ? window.getTelemetryConsent() : false;
@@ -809,7 +849,6 @@ async function startGeneration() {
         selectedWorld: worldPath,
         worldScale: scale,
         groundLevel: ground_level,
-        floodfillTimeout: floodfill_timeout,
         terrainEnabled: terrain,
         skipOsmObjects: skipOsmObjects,
         interiorEnabled: interior,

src/gui/locales/ar.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "اختيار موقع",
-  "zoom_in_and_choose": "قم بالتكبير واختر منطقتك باستخدام أداة المستطيل",
-  "select_world": "تحديد عالم",
   "choose_world": "اختيار عالم",
   "no_world_selected": "لم يتم تحديد عالم",
   "start_generation": "بدء البناء",
-  "progress": "التقدم",
   "custom_selection_confirmed": "تم تأكيد التحديد المخصص!",
   "error_coordinates_out_of_range": "خطأ: الإحداثيات خارج النطاق أو مرتبة بشكل غير صحيح (مطلوب خط العرض قبل خط الطول).",
   "invalid_format": "تنسيق غير صالح. استخدم 'lat,lng,lat,lng' أو 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "تُعتبر هذه المنطقة كبيرة جدًا وقد تتجاوز حدود الحوسبة النموذجية.",
   "area_extensive": "المنطقة واسعة جدًا وقد تتطلب الكثير من الوقت والموارد.",
   "selection_confirmed": "تم تأكيد التحديد!",
+  "select_area_prompt": "حدد منطقة على الخريطة باستخدام الأدوات.",
   "unknown_error": "خطأ غير معروف",
   "license_and_credits": "الرخصة والمساهمون",
   "placeholder_bbox": "الصيغة: lat,lng,lat,lng",

src/gui/locales/de.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Standort auswählen",
-  "zoom_in_and_choose": "Zoome hinein und wähle dein Gebiet aus",
-  "select_world": "Welt auswählen",
   "choose_world": "Welt wählen",
   "no_world_selected": "Keine Welt ausgewählt",
   "start_generation": "Generierung starten",
-  "progress": "Fortschritt",
   "custom_selection_confirmed": "Benutzerdefinierte Auswahl bestätigt!",
   "error_coordinates_out_of_range": "Fehler: Koordinaten sind außerhalb des Bereichs oder falsch geordnet (Lat vor Lng erforderlich).",
   "invalid_format": "Ungültiges Format. Bitte verwende 'lat,lng,lat,lng' oder 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Dieses Gebiet ist sehr groß und könnte das Berechnungslimit überschreiten.",
   "area_extensive": "Diese Gebietsgröße könnte längere Zeit für die Generierung benötigen.",
   "selection_confirmed": "Auswahl bestätigt!",
+  "select_area_prompt": "Wähle einen Bereich auf der Karte aus.",
   "unknown_error": "Unbekannter Fehler",
   "license_and_credits": "Lizenz und Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/en-US.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Select Location",
-  "zoom_in_and_choose": "Zoom in and choose your area using the rectangle tool",
-  "select_world": "Select World",
   "choose_world": "Choose World",
   "no_world_selected": "No world selected",
   "start_generation": "Start Generation",
-  "progress": "Progress",
   "custom_selection_confirmed": "Custom selection confirmed!",
   "error_coordinates_out_of_range": "Error: Coordinates are out of range or incorrectly ordered (Lat before Lng required).",
   "invalid_format": "Invalid format. Please use 'lat,lng,lat,lng' or 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "This area is very large and could exceed typical computing limits.",
   "area_extensive": "The area is quite extensive and may take significant time and resources.",
   "selection_confirmed": "Selection confirmed!",
+  "select_area_prompt": "Select an area on the map using the tools.",
   "unknown_error": "Unknown error",
   "license_and_credits": "License and Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/es.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Seleccionar ubicación",
-  "zoom_in_and_choose": "Acércate y elige tu área usando la herramienta de rectángulo",
-  "select_world": "Seleccionar mundo",
   "choose_world": "Elegir mundo",
   "no_world_selected": "Ningún mundo seleccionado",
   "start_generation": "Iniciar generación",
-  "progress": "Progreso",
   "custom_selection_confirmed": "¡Selección personalizada confirmada!",
   "error_coordinates_out_of_range": "Error: Las coordenadas están fuera de rango o están ordenadas incorrectamente (Lat antes de Lng requerido).",
   "invalid_format": "Formato inválido. Por favor, use 'lat,lng,lat,lng' o 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Esta área es muy grande y podría exceder los límites típicos de computación.",
   "area_extensive": "El área es bastante extensa y puede requerir mucho tiempo y recursos.",
   "selection_confirmed": "¡Selección confirmada!",
+  "select_area_prompt": "Selecciona un área en el mapa usando las herramientas.",
   "unknown_error": "Unknown error",
   "license_and_credits": "License and Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/fi.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Valitse paikka",
-  "zoom_in_and_choose": "Zoomaa ja valitse paikka käyttämällä suorakulmatyökalua.",
-  "select_world": "Valitse maailma",
   "choose_world": "Valitse maailma",
   "no_world_selected": "Maailmaa ei valittu",
   "start_generation": "Aloita generointi",
-  "progress": "Edistys",
   "custom_selection_confirmed": "Mukautettu valinta vahvistettu!",
   "error_coordinates_out_of_range": "Virhe: Koordinaatit ovat kantaman ulkopuolella tai vääriin aseteltu (Lat ennen Lng vaadittu).",
   "invalid_format": "Väärä formaatti. Käytä 'lat,lng,lat,lng' tai 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Tämä alue on todella iso ja voi ylittää tyypilliset laskentarajat.",
   "area_extensive": "Alue on aika laaja ja voi viedä pitkän ajan ja resursseja.",
   "selection_confirmed": "Valinta vahvistettu!",
+  "select_area_prompt": "Valitse alue kartalta työkaluilla.",
   "unknown_error": "Tuntematon virhe",
   "license_and_credits": "Lisenssi ja krediitit",
   "placeholder_bbox": "Formaatti: lat,lng,lat,lng",

src/gui/locales/fr-FR.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Sélectionner une localisation",
-  "zoom_in_and_choose": "Zoomez et choisissez votre zone avec l'outil rectangle",
-  "select_world": "Sélectionner un monde",
   "choose_world": "Choisir un monde",
   "no_world_selected": "Aucun monde sélectionné",
   "start_generation": "Commencer la génération",
-  "progress": "Progrès",
   "custom_selection_confirmed": "Sélection personnalisée confirmée !",
   "error_coordinates_out_of_range": "Erreur: Coordonnées hors de portée ou dans un ordre incorrect (besoin de la latitude avant la longitude).",
   "invalid_format": "Format invalide. Utilisez 'lat,lng,lat,lng' ou 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Cette zone est très grande et pourrait dépasser les limites de calcul courantes.",
   "area_extensive": "Cette zone est très étendue et pourrait nécessiter beaucoup de ressources et de temps.",
   "selection_confirmed": "Sélection confirmée !",
+  "select_area_prompt": "Sélectionnez une zone sur la carte avec les outils.",
   "unknown_error": "Erreur inconnue",
   "license_and_credits": "Licence et crédits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/hu.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Hely kiválasztása",
-  "zoom_in_and_choose": "Nagyíts és jelöld ki a területet a kijelölő eszközzel",
-  "select_world": "Világ kijelölése",
   "choose_world": "Világ kiválasztása",
   "no_world_selected": "Nincs világ kiválasztva",
   "start_generation": "Generálás indítása",
-  "progress": "Haladás",
   "custom_selection_confirmed": "Egyéni kiválasztás megerősítve",
   "error_coordinates_out_of_range": "Hiba: A koordináták tartományon kívül vannak vagy hibásan rendezettek (a szélességi foknak a hosszúsági fok előtt kell lennie)",
   "invalid_format": "Érvénytelen formátum. Kérjük, használja a 'lat,lng,lat,lng' vagy a 'lat lng lat lng' formátumot.'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Ez a terület nagyon nagy, és meghaladhatja a szokásos számítási korlátokat.",
   "area_extensive": "A terület meglehetősen kiterjedt, és jelentős időt és erőforrásokat igényelhet.",
   "selection_confirmed": "Kiválasztás megerősítve",
+  "select_area_prompt": "Jelölj ki egy területet a térképen az eszközökkel.",
   "unknown_error": "Ismeretlen hiba",
   "license_and_credits": "Licenc és elismerés.",
   "placeholder_bbox": "Formátum: lat,lng,lat,lng",

src/gui/locales/ko.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "장소 선택",
-  "zoom_in_and_choose": "줌 인하고 직사각형 도구를 사용하여 영역을 선택하세요.",
-  "select_world": "세계 선택",
   "choose_world": "세계 선택",
   "no_world_selected": "선택된 세계 없음",
   "start_generation": "생성 시작",
-  "progress": "진행",
   "custom_selection_confirmed": "사용자 지정 선택이 확인되었습니다!",
   "error_coordinates_out_of_range": "오류: 좌표가 범위를 벗어나거나 잘못된 순서입니다 (Lat이 Lng보다 먼저 필요합니다).",
   "invalid_format": "잘못된 형식입니다. 'lat,lng,lat,lng' 또는 'lat lng lat lng' 형식을 사용하세요.",
@@ -28,8 +24,9 @@
   "select_minecraft_world_first": "먼저 마인크래프트 세계를 선택하세요!",
   "select_location_first": "먼저 위치를 선택하세요!",
   "area_too_large": "이 지역은 매우 크고, 일반적인 계산 한계를 초과할 수 있습니다.",
-  "area_extensive": "이 지역은 꽤 광범위하여 значитель한 시간과 자원이 필요할 수 있습니다.",
+  "area_extensive": "이 지역은 꽤 광범위하여 상당한 시간과 자원이 필요할 수 있습니다.",
   "selection_confirmed": "선택이 확인되었습니다!",
+  "select_area_prompt": "도구를 사용하여 지도에서 영역을 선택하세요.",
   "unknown_error": "Unknown error",
   "license_and_credits": "License and Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/lt.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Vietos pasirinkimas",
-  "zoom_in_and_choose": "Pasididinkite žemėlapį ir pasirinkite plotą su kvadrato įrankiu",
-  "select_world": "Pasaulio pasirinkimas",
   "choose_world": "Pasirinkti pasaulį",
   "no_world_selected": "Pasaulis nepasirinktas",
   "start_generation": "Pradėti generaciją",
-  "progress": "Progresas",
   "custom_selection_confirmed": "Rėmo pasirinkimas patvirtintas!",
   "error_coordinates_out_of_range": "Klaida: Koordinatės yra už ribų arba neteisingai išdėstytos (plat turi būti prieš ilg).",
   "invalid_format": "Neteisingas formatas. Prašome naudoti 'plat,ilg,plat,ilg' arba 'plat ilg plat ilg'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Šis plotas yra labai didelis ir gali viršyti tipinius resursų limitus.",
   "area_extensive": "Šis plotas yra pakankamai didelis kuriam reikėtų daug laiko ir resursų.",
   "selection_confirmed": "Pasirinkimas patvirtintas!",
+  "select_area_prompt": "Pasirinkite plotą žemėlapyje naudodami įrankius.",
   "unknown_error": "Nežinoma klaida",
   "license_and_credits": "Licencija ir padėkos",
   "placeholder_bbox": "Formatas: plat,lyg,plat,lyg",

src/gui/locales/lv.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Izvēlēties atrašanās vietu",
-  "zoom_in_and_choose": "Pietuviniet un izvēlieties apgabalu",
-  "select_world": "Izvēlēties pasauli",
   "choose_world": "Izvēlēties pasauli",
   "no_world_selected": "Pasaulē nav izvēlēta",
   "start_generation": "Sākt ģenerēšanu",
-  "progress": "Progress",
   "custom_selection_confirmed": "Pielāgota izvēle apstiprināta!",
   "error_coordinates_out_of_range": "Kļūda: koordinātas ir ārpus darbības zonas vai norādītas nepareizā secībā (vispirms platums, tad garums)",
   "invalid_format": "Nederīgs formāts. Izmantojiet 'platums,garums,platums,garums' vai 'platums garums platums garums'",
@@ -30,6 +26,7 @@
   "area_too_large": "Šis apgabals ir pārāk liels un var pārsniegt tipiskos aprēķina ierobežojumus",
   "area_extensive": "Apgabals ir diezgan plašs un var prasīt ievērojamu laiku un resursus",
   "selection_confirmed": "Izvēle apstiprināta!",
+  "select_area_prompt": "Izvēlieties apgabalu kartē, izmantojot rīkus.",
   "unknown_error": "Nezināma kļūda",
   "license_and_credits": "Licence un autori",
   "placeholder_bbox": "Formāts: platums,garums,platums,garums",

src/gui/locales/pl.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Wybierz lokalizację",
-  "zoom_in_and_choose": "Przybliż i zaznacz obszar za pomocą prostokąta",
-  "select_world": "Wybierz świat",
   "choose_world": "Wybierz świat",
   "no_world_selected": "Nie wybrano świata",
   "start_generation": "Rozpocznij generowanie",
-  "progress": "Postęp",
   "custom_selection_confirmed": "Niestandardowy wybór potwierdzony!",
   "error_coordinates_out_of_range": "Błąd: Współrzędne są poza zakresem lub w złej kolejności (wymagana szerokość przed długością).",
   "invalid_format": "Nieprawidłowy format. Użyj 'szer.,dł.,szer.,dł.' lub 'szer. dł. szer. dł.'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Ten obszar jest bardzo duży i może przekroczyć limity obliczeniowe.",
   "area_extensive": "Ten obszar jest rozległy i może pochłonąć dużo czasu oraz zasobów.",
   "selection_confirmed": "Wybór potwierdzony!",
+  "select_area_prompt": "Zaznacz obszar na mapie za pomocą narzędzi.",
   "unknown_error": "Nieznany błąd",
   "license_and_credits": "Licencja i autorzy",
   "placeholder_bbox": "Format: szer,dł,szer,dł",

src/gui/locales/ru.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Выбрать местоположение",
-  "zoom_in_and_choose": "Приблизьте и выберите область",
-  "select_world": "Выбрать мир",
   "choose_world": "Выбрать мир",
   "no_world_selected": "Мир не выбран",
   "start_generation": "Начать генерацию",
-  "progress": "Прогресс",
   "custom_selection_confirmed": "Пользовательский выбор подтвержден!",
   "error_coordinates_out_of_range": "Ошибка: Координаты находятся вне зоны действия или указаны в неправильном порядке (сначала широта, затем долгота)",
   "invalid_format": "Неверный формат. Используйте 'широта,долгота,широта,долгота' или 'широта долгота широта долгота'",
@@ -30,6 +26,7 @@
   "area_too_large": "Эта область слишком велика и может превысить типичные вычислительные ограничения",
   "area_extensive": "Область довольно обширна и может потребовать значительного времени и ресурсов",
   "selection_confirmed": "Выбор подтвержден!",
+  "select_area_prompt": "Выберите область на карте с помощью инструментов.",
   "unknown_error": "Неизвестная ошибка",
   "license_and_credits": "Лицензия и авторы",
   "placeholder_bbox": "Формат: широта,долгота,широта,долгота",

src/gui/locales/sv.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Välj plats",
-  "zoom_in_and_choose": "Zooma in och välj ditt område med rektangulärt verktyg",
-  "select_world": "Välj värld",
   "choose_world": "Välj värld",
   "no_world_selected": "Ingen värld vald",
   "start_generation": "Starta generering",
-  "progress": "Framsteg",
   "custom_selection_confirmed": "Anpassad markering bekräftad!",
   "error_coordinates_out_of_range": "Fel: Koordinater är utanför området eller felaktigt ordnade (Lat före Lng krävs).",
   "invalid_format": "Ogiltigt format. Använd 'lat,lng,lat,lng' eller 'lat lng lat lng'.",
@@ -30,6 +26,7 @@
   "area_too_large": "Detta område är mycket stort och kan överskrida vanliga beräkningsgränser.",
   "area_extensive": "Området är ganska extensivt och kan ta betydande tid och resurser.",
   "selection_confirmed": "Val bekräftat!",
+  "select_area_prompt": "Välj ett område på kartan med verktygen.",
   "unknown_error": "Unknown error",
   "license_and_credits": "License and Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/ua.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "Обрати локацію",
-  "zoom_in_and_choose": "Збільште і оберіть область за допомогою прямокутника",
-  "select_world": "Обрати світ",
   "choose_world": "Обрати світ",
   "no_world_selected": "Світ не обрано",
   "start_generation": "Почати генерацію",
-  "progress": "Прогрес",
   "custom_selection_confirmed": "Користувацький вибір підтверджено!",
   "error_coordinates_out_of_range": "Помилка: Координати поза діапазоном або неправильно впорядковані (потрібно широта перед довгота)",
   "invalid_format": "Неправильний формат. Будь ласка, використовуйте 'широта,довгота,широта,довгота' або 'широта довгота широта довгота'",
@@ -30,6 +26,7 @@
   "area_too_large": "Ця область дуже велика і може перевищити типові обчислювальні межі",
   "area_extensive": "Область досить велика і може вимагати значного часу та ресурсів",
   "selection_confirmed": "Вибір підтверджено!",
+  "select_area_prompt": "Виберіть область на карті за допомогою інструментів.",
   "unknown_error": "Unknown error",
   "license_and_credits": "License and Credits",
   "placeholder_bbox": "Format: lat,lng,lat,lng",

src/gui/locales/zh-CN.json

@@ -1,11 +1,7 @@
 {
-  "select_location": "选择位置",
-  "zoom_in_and_choose": "放大并使用矩形工具选择您的区域",
-  "select_world": "选择世界",
   "choose_world": "选择世界",
   "no_world_selected": "未选择世界",
   "start_generation": "开始生成",
-  "progress": "进度",
   "custom_selection_confirmed": "自定义选择已确认！",
   "error_coordinates_out_of_range": "错误：坐标超出范围或顺序不正确（需要先纬度后经度）。",
   "invalid_format": "格式无效。请使用 'lat,lng,lat,lng' 或 'lat lng lat lng'。",
@@ -30,6 +26,7 @@
   "area_too_large": "该区域非常大，可能会超出典型的计算限制。",
   "area_extensive": "该区域相当广泛，可能需要大量时间和资源。",
   "selection_confirmed": "选择已确认！",
+  "select_area_prompt": "使用工具在地图上选择一个区域。",
   "unknown_error": "未知错误",
   "license_and_credits": "许可证和致谢",
   "placeholder_bbox": "格式: lat,lng,lat,lng",

src/gui/maps.html

@@ -26,7 +26,7 @@
     <div id="search-container">
         <div id="search-box">
             <input type="text" id="city-search" placeholder="Search for a city..." autocomplete="off" />
-            <button id="search-btn">🔍</button>
+            <button id="search-btn" aria-label="Search"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><circle cx="11" cy="11" r="8"></circle><path d="m21 21-4.3-4.3"></path></svg></button>
         </div>
         <div id="search-results"></div>
     </div>

src/main.rs

@@ -9,9 +9,11 @@ mod clipping;
 mod colors;
 mod coordinate_system;
 mod data_processing;
+mod deterministic_rng;
 mod element_processing;
 mod elevation_data;
 mod floodfill;
+mod floodfill_cache;
 mod ground;
 mod map_renderer;
 mod map_transformation;
@@ -49,6 +51,9 @@ mod progress {
 use windows::Win32::System::Console::{AttachConsole, FreeConsole, ATTACH_PARENT_PROCESS};
 
 fn run_cli() {
+    // Configure thread pool with 90% CPU cap to keep system responsive
+    floodfill_cache::configure_rayon_thread_pool(0.9);
+
     let version: &str = env!("CARGO_PKG_VERSION");
     let repository: &str = env!("CARGO_PKG_REPOSITORY");
     println!(

src/osm_parser.rs

@@ -5,8 +5,8 @@ use crate::coordinate_system::transformation::CoordTransformer;
 use crate::progress::emit_gui_progress_update;
 use colored::Colorize;
 use serde::Deserialize;
-use serde_json::Value;
 use std::collections::HashMap;
+use std::sync::Arc;
 
 // Raw data from OSM
 
@@ -29,9 +29,18 @@ struct OsmElement {
     pub members: Vec<OsmMember>,
 }
 
-#[derive(Deserialize)]
-struct OsmData {
-    pub elements: Vec<OsmElement>,
+#[derive(Debug, Deserialize)]
+pub struct OsmData {
+    elements: Vec<OsmElement>,
+    #[serde(default)]
+    pub remark: Option<String>,
+}
+
+impl OsmData {
+    /// Returns true if there are no elements in the OSM data
+    pub fn is_empty(&self) -> bool {
+        self.elements.is_empty()
+    }
 }
 
 struct SplitOsmData {
@@ -68,11 +77,6 @@ impl SplitOsmData {
     }
 }
 
-fn parse_raw_osm_data(json_data: Value) -> Result<SplitOsmData, serde_json::Error> {
-    let osm_data: OsmData = serde_json::from_value(json_data)?;
-    Ok(SplitOsmData::from_raw_osm_data(osm_data))
-}
-
 // End raw data
 
 // Normalized data that we can use
@@ -112,7 +116,7 @@ pub enum ProcessedMemberRole {
 #[derive(Debug, Clone, PartialEq)]
 pub struct ProcessedMember {
     pub role: ProcessedMemberRole,
-    pub way: ProcessedWay,
+    pub way: Arc<ProcessedWay>,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -164,7 +168,7 @@ impl ProcessedElement {
 }
 
 pub fn parse_osm_data(
-    json_data: Value,
+    osm_data: OsmData,
     bbox: LLBBox,
     scale: f64,
     debug: bool,
@@ -174,7 +178,7 @@ pub fn parse_osm_data(
     emit_gui_progress_update(5.0, "Parsing data...");
 
     // Deserialize the JSON data into the OSMData structure
-    let data = parse_raw_osm_data(json_data).expect("Failed to parse OSM data");
+    let data = SplitOsmData::from_raw_osm_data(osm_data);
 
     let (coord_transformer, xzbbox) = CoordTransformer::llbbox_to_xzbbox(&bbox, scale)
         .unwrap_or_else(|e| {
@@ -189,7 +193,7 @@ pub fn parse_osm_data(
     }
 
     let mut nodes_map: HashMap<u64, ProcessedNode> = HashMap::new();
-    let mut ways_map: HashMap<u64, ProcessedWay> = HashMap::new();
+    let mut ways_map: HashMap<u64, Arc<ProcessedWay>> = HashMap::new();
 
     let mut processed_elements: Vec<ProcessedElement> = Vec::new();
 
@@ -238,17 +242,15 @@ pub fn parse_osm_data(
         let tags = element.tags.clone().unwrap_or_default();
 
         // Store unclipped way for relation assembly (clipping happens after ring merging)
-        ways_map.insert(
-            element.id,
-            ProcessedWay {
-                id: element.id,
-                tags: tags.clone(),
-                nodes: nodes.clone(),
-            },
-        );
+        let way = Arc::new(ProcessedWay {
+            id: element.id,
+            tags,
+            nodes,
+        });
+        ways_map.insert(element.id, Arc::clone(&way));
 
         // Clip way nodes for standalone way processing (not relations)
-        let clipped_nodes = clip_way_to_bbox(&nodes, &xzbbox);
+        let clipped_nodes = clip_way_to_bbox(&way.nodes, &xzbbox);
 
         // Skip ways that are completely outside the bbox (empty after clipping)
         if clipped_nodes.is_empty() {
@@ -257,8 +259,8 @@ pub fn parse_osm_data(
 
         let processed: ProcessedWay = ProcessedWay {
             id: element.id,
-            tags: tags.clone(),
-            nodes: clipped_nodes.clone(),
+            tags: way.tags.clone(),
+            nodes: clipped_nodes,
         };
 
         processed_elements.push(ProcessedElement::Way(processed));
@@ -294,8 +296,8 @@ pub fn parse_osm_data(
                 };
 
                 // Check if the way exists in ways_map
-                let way: ProcessedWay = match ways_map.get(&mem.r#ref) {
-                    Some(w) => w.clone(),
+                let way = match ways_map.get(&mem.r#ref) {
+                    Some(w) => Arc::clone(w),
                     None => {
                         // Way was likely filtered out because it was completely outside the bbox
                         return None;
@@ -311,11 +313,11 @@ pub fn parse_osm_data(
                     if clipped_nodes.is_empty() {
                         return None;
                     }
-                    ProcessedWay {
+                    Arc::new(ProcessedWay {
                         id: way.id,
-                        tags: way.tags,
+                        tags: way.tags.clone(),
                         nodes: clipped_nodes,
-                    }
+                    })
                 };
 
                 Some(ProcessedMember {
@@ -336,6 +338,9 @@ pub fn parse_osm_data(
 
     emit_gui_progress_update(15.0, "");
 
+    drop(nodes_map);
+    drop(ways_map);
+
     (processed_elements, xzbbox)
 }
 

src/retrieve_data.rs

@@ -1,12 +1,14 @@
 use crate::coordinate_system::geographic::LLBBox;
+use crate::osm_parser::OsmData;
 use crate::progress::{emit_gui_error, emit_gui_progress_update, is_running_with_gui};
 use colored::Colorize;
 use rand::seq::SliceRandom;
 use reqwest::blocking::Client;
 use reqwest::blocking::ClientBuilder;
+use serde::Deserialize;
 use serde_json::Value;
 use std::fs::File;
-use std::io::{self, BufReader, Write};
+use std::io::{self, BufReader, Cursor, Write};
 use std::process::Command;
 use std::time::Duration;
 
@@ -34,19 +36,17 @@ fn download_with_reqwest(url: &str, query: &str) -> Result<String, Box<dyn std::
         }
         Err(e) => {
             if e.is_timeout() {
-                eprintln!(
-                    "{}",
-                    "Error! Request timed out. Try selecting a smaller area."
-                        .red()
-                        .bold()
-                );
-                emit_gui_error("Request timed out. Try selecting a smaller area.");
+                let msg = "Request timed out. Try selecting a smaller area.";
+                eprintln!("{}", format!("Error! {msg}").red().bold());
+                Err(msg.into())
+            } else if e.is_connect() {
+                let msg = "No internet connection.";
+                eprintln!("{}", format!("Error! {msg}").red().bold());
+                Err(msg.into())
             } else {
                 eprintln!("{}", format!("Error! {e:.52}").red().bold());
-                emit_gui_error(&format!("{:.52}", e.to_string()));
+                Err(format!("{e:.52}").into())
             }
-            // Always propagate errors
-            Err(e.into())
         }
     }
 }
@@ -79,13 +79,14 @@ fn download_with_wget(url: &str, query: &str) -> io::Result<String> {
     }
 }
 
-pub fn fetch_data_from_file(file: &str) -> Result<Value, Box<dyn std::error::Error>> {
+pub fn fetch_data_from_file(file: &str) -> Result<OsmData, Box<dyn std::error::Error>> {
     println!("{} Loading data from file...", "[1/7]".bold());
     emit_gui_progress_update(1.0, "Loading data from file...");
 
     let file: File = File::open(file)?;
     let reader: BufReader<File> = BufReader::new(file);
-    let data: Value = serde_json::from_reader(reader)?;
+    let mut deserializer = serde_json::Deserializer::from_reader(reader);
+    let data: OsmData = OsmData::deserialize(&mut deserializer)?;
     Ok(data)
 }
 
@@ -95,7 +96,7 @@ pub fn fetch_data_from_overpass(
     debug: bool,
     download_method: &str,
     save_file: Option<&str>,
-) -> Result<Value, Box<dyn std::error::Error>> {
+) -> Result<OsmData, Box<dyn std::error::Error>> {
     println!("{} Fetching data...", "[1/7]".bold());
     emit_gui_progress_update(1.0, "Fetching data...");
 
@@ -182,14 +183,12 @@ pub fn fetch_data_from_overpass(
             println!("API response saved to: {save_file}");
         }
 
-        let data: Value = serde_json::from_str(&response)?;
+        let mut deserializer =
+            serde_json::Deserializer::from_reader(Cursor::new(response.as_bytes()));
+        let data: OsmData = OsmData::deserialize(&mut deserializer)?;
 
-        if data["elements"]
-            .as_array()
-            .map_or(0, |elements: &Vec<Value>| elements.len())
-            == 0
-        {
-            if let Some(remark) = data["remark"].as_str() {
+        if data.is_empty() {
+            if let Some(remark) = data.remark.as_deref() {
                 // Check if the remark mentions memory or other runtime errors
                 if remark.contains("runtime error") && remark.contains("out of memory") {
                     eprintln!("{}", "Error! The query ran out of memory on the Overpass API server. Try using a smaller area.".red().bold());
@@ -211,7 +210,7 @@ pub fn fetch_data_from_overpass(
             }
 
             if debug {
-                println!("Additional debug information: {data}");
+                println!("Additional debug information: {data:?}");
             }
 
             if !is_running_with_gui() {

src/test_utilities.rs

@@ -7,9 +7,8 @@ use crate::retrieve_data;
 // this is copied from main.rs
 pub fn generate_example(llbbox: LLBBox) -> (XZBBox, Vec<ProcessedElement>) {
     // Fetch data
-    let raw_data: serde_json::Value =
-        retrieve_data::fetch_data_from_overpass(llbbox, false, "requests", None)
-            .expect("Failed to fetch data");
+    let raw_data = retrieve_data::fetch_data_from_overpass(llbbox, false, "requests", None)
+        .expect("Failed to fetch data");
 
     // Parse raw data
     let (mut parsed_elements, xzbbox) = osm_parser::parse_osm_data(raw_data, llbbox, 1.0, false);

src/world_editor/bedrock.rs

@@ -24,6 +24,7 @@ use std::collections::HashMap as StdHashMap;
 use std::fs::{self, File};
 use std::io::{Cursor, Write as IoWrite};
 use std::path::PathBuf;
+use std::sync::Arc;
 use vek::Vec2;
 use zip::write::FileOptions;
 use zip::CompressionMethod;
@@ -122,7 +123,7 @@ pub struct BedrockWriter {
     output_dir: PathBuf,
     level_name: String,
     spawn_point: Option<(i32, i32)>,
-    ground: Option<Box<Ground>>,
+    ground: Option<Arc<Ground>>,
 }
 
 impl BedrockWriter {
@@ -131,7 +132,7 @@ impl BedrockWriter {
         output_path: PathBuf,
         level_name: String,
         spawn_point: Option<(i32, i32)>,
-        ground: Option<Box<Ground>>,
+        ground: Option<Arc<Ground>>,
     ) -> Self {
         // If the path ends with .mcworld, use it as the final archive path
         // and create a temp directory without that extension for working files
@@ -214,8 +215,11 @@ impl BedrockWriter {
             .ground
             .as_ref()
             .map(|ground| {
-                let coord = crate::coordinate_system::cartesian::XZPoint::new(spawn_x, spawn_z);
-                ground.level(coord) + 2 // Add 2 blocks above ground for safety
+                // Ground elevation data expects coordinates relative to the XZ bbox origin
+                let rel_x = spawn_x - xzbbox.min_x();
+                let rel_z = spawn_z - xzbbox.min_z();
+                let coord = crate::coordinate_system::cartesian::XZPoint::new(rel_x, rel_z);
+                ground.level(coord) + 3 // Add 3 blocks above ground for safety
             })
             .unwrap_or(64);
 

src/world_editor/common.rs

@@ -4,6 +4,11 @@
 //! before they are written to either Java or Bedrock format.
 
 use crate::block_definitions::*;
+
+/// Minimum Y coordinate in Minecraft (1.18+)
+const MIN_Y: i32 = -64;
+/// Maximum Y coordinate in Minecraft (1.18+)
+const MAX_Y: i32 = 319;
 use fastnbt::{LongArray, Value};
 use fnv::FnvHashMap;
 use serde::{Deserialize, Serialize};
@@ -150,7 +155,7 @@ impl SectionToModify {
         let palette = unique_blocks
             .iter()
             .map(|(block, stored_props)| PaletteItem {
-                name: block.name().to_string(),
+                name: format!("{}:{}", block.namespace(), block.name()),
                 properties: stored_props.clone().or_else(|| block.properties()),
             })
             .collect();
@@ -186,16 +191,20 @@ pub(crate) struct ChunkToModify {
 impl ChunkToModify {
     #[inline]
     pub fn get_block(&self, x: u8, y: i32, z: u8) -> Option<Block> {
-        let section_idx: i8 = (y >> 4).try_into().unwrap();
+        // Clamp Y to valid Minecraft range to prevent TryFromIntError
+        let y = y.clamp(MIN_Y, MAX_Y);
+        let section_idx: i8 = (y >> 4) as i8;
         let section = self.sections.get(&section_idx)?;
-        section.get_block(x, (y & 15).try_into().unwrap(), z)
+        section.get_block(x, (y & 15) as u8, z)
     }
 
     #[inline]
     pub fn set_block(&mut self, x: u8, y: i32, z: u8, block: Block) {
-        let section_idx: i8 = (y >> 4).try_into().unwrap();
+        // Clamp Y to valid Minecraft range to prevent TryFromIntError
+        let y = y.clamp(MIN_Y, MAX_Y);
+        let section_idx: i8 = (y >> 4) as i8;
         let section = self.sections.entry(section_idx).or_default();
-        section.set_block(x, (y & 15).try_into().unwrap(), z, block);
+        section.set_block(x, (y & 15) as u8, z, block);
     }
 
     #[inline]
@@ -206,9 +215,11 @@ impl ChunkToModify {
         z: u8,
         block_with_props: BlockWithProperties,
     ) {
-        let section_idx: i8 = (y >> 4).try_into().unwrap();
+        // Clamp Y to valid Minecraft range to prevent TryFromIntError
+        let y = y.clamp(MIN_Y, MAX_Y);
+        let section_idx: i8 = (y >> 4) as i8;
         let section = self.sections.entry(section_idx).or_default();
-        section.set_block_with_properties(x, (y & 15).try_into().unwrap(), z, block_with_props);
+        section.set_block_with_properties(x, (y & 15) as u8, z, block_with_props);
     }
 
     pub fn sections(&self) -> impl Iterator<Item = Section> + '_ {

src/world_editor/java.rs

@@ -23,9 +23,11 @@ use crate::telemetry::{send_log, LogLevel};
 impl<'a> WorldEditor<'a> {
     /// Creates a region file for the given region coordinates.
     pub(super) fn create_region(&self, region_x: i32, region_z: i32) -> Region<File> {
-        let out_path = self
-            .world_dir
-            .join(format!("region/r.{}.{}.mca", region_x, region_z));
+        let region_dir = self.world_dir.join("region");
+        let out_path = region_dir.join(format!("r.{}.{}.mca", region_x, region_z));
+
+        // Ensure region directory exists before creating region files
+        std::fs::create_dir_all(&region_dir).expect("Failed to create region directory");
 
         const REGION_TEMPLATE: &[u8] = include_bytes!("../../assets/minecraft/region.template");
 
@@ -75,6 +77,8 @@ impl<'a> WorldEditor<'a> {
     }
 
     /// Saves the world in Java Edition Anvil format.
+    ///
+    /// Uses parallel processing with rayon for fast region saving.
     pub(super) fn save_java(&mut self) {
         println!("{} Saving world...", "[7/7]".bold());
         emit_gui_progress_update(90.0, "Saving world...");
@@ -104,122 +108,12 @@ impl<'a> WorldEditor<'a> {
             .regions
             .par_iter()
             .for_each(|((region_x, region_z), region_to_modify)| {
-                let mut region = self.create_region(*region_x, *region_z);
-                let mut ser_buffer = Vec::with_capacity(8192);
-
-                for (&(chunk_x, chunk_z), chunk_to_modify) in &region_to_modify.chunks {
-                    if !chunk_to_modify.sections.is_empty() || !chunk_to_modify.other.is_empty() {
-                        // Read existing chunk data if it exists
-                        let existing_data = region
-                            .read_chunk(chunk_x as usize, chunk_z as usize)
-                            .unwrap()
-                            .unwrap_or_default();
-
-                        // Parse existing chunk or create new one
-                        let mut chunk: Chunk = if !existing_data.is_empty() {
-                            fastnbt::from_bytes(&existing_data).unwrap()
-                        } else {
-                            Chunk {
-                                sections: Vec::new(),
-                                x_pos: chunk_x + (region_x * 32),
-                                z_pos: chunk_z + (region_z * 32),
-                                is_light_on: 0,
-                                other: FnvHashMap::default(),
-                            }
-                        };
-
-                        // Update sections while preserving existing data
-                        let new_sections: Vec<Section> = chunk_to_modify.sections().collect();
-                        for new_section in new_sections {
-                            if let Some(existing_section) =
-                                chunk.sections.iter_mut().find(|s| s.y == new_section.y)
-                            {
-                                // Merge block states
-                                existing_section.block_states.palette =
-                                    new_section.block_states.palette;
-                                existing_section.block_states.data = new_section.block_states.data;
-                            } else {
-                                // Add new section if it doesn't exist
-                                chunk.sections.push(new_section);
-                            }
-                        }
-
-                        // Preserve existing block entities and merge with new ones
-                        if let Some(existing_entities) = chunk.other.get_mut("block_entities") {
-                            if let Some(new_entities) = chunk_to_modify.other.get("block_entities")
-                            {
-                                if let (Value::List(existing), Value::List(new)) =
-                                    (existing_entities, new_entities)
-                                {
-                                    // Remove old entities that are replaced by new ones
-                                    existing.retain(|e| {
-                                        if let Value::Compound(map) = e {
-                                            let (x, y, z) = get_entity_coords(map);
-                                            !new.iter().any(|new_e| {
-                                                if let Value::Compound(new_map) = new_e {
-                                                    let (nx, ny, nz) = get_entity_coords(new_map);
-                                                    x == nx && y == ny && z == nz
-                                                } else {
-                                                    false
-                                                }
-                                            })
-                                        } else {
-                                            true
-                                        }
-                                    });
-                                    // Add new entities
-                                    existing.extend(new.clone());
-                                }
-                            }
-                        } else {
-                            // If no existing entities, just add the new ones
-                            if let Some(new_entities) = chunk_to_modify.other.get("block_entities")
-                            {
-                                chunk
-                                    .other
-                                    .insert("block_entities".to_string(), new_entities.clone());
-                            }
-                        }
-
-                        // Update chunk coordinates and flags
-                        chunk.x_pos = chunk_x + (region_x * 32);
-                        chunk.z_pos = chunk_z + (region_z * 32);
-
-                        // Create Level wrapper and save
-                        let level_data = create_level_wrapper(&chunk);
-                        ser_buffer.clear();
-                        fastnbt::to_writer(&mut ser_buffer, &level_data).unwrap();
-                        region
-                            .write_chunk(chunk_x as usize, chunk_z as usize, &ser_buffer)
-                            .unwrap();
-                    }
-                }
-
-                // Second pass: ensure all chunks exist
-                for chunk_x in 0..32 {
-                    for chunk_z in 0..32 {
-                        let abs_chunk_x = chunk_x + (region_x * 32);
-                        let abs_chunk_z = chunk_z + (region_z * 32);
-
-                        // Check if chunk exists in our modifications
-                        let chunk_exists =
-                            region_to_modify.chunks.contains_key(&(chunk_x, chunk_z));
-
-                        // If chunk doesn't exist, create it with base layer
-                        if !chunk_exists {
-                            let (ser_buffer, _) = Self::create_base_chunk(abs_chunk_x, abs_chunk_z);
-                            region
-                                .write_chunk(chunk_x as usize, chunk_z as usize, &ser_buffer)
-                                .unwrap();
-                        }
-                    }
-                }
+                self.save_single_region(*region_x, *region_z, region_to_modify);
 
                 // Update progress
                 let regions_done = regions_processed.fetch_add(1, Ordering::SeqCst) + 1;
 
-                // Update progress at regular intervals (every ~1% or at least every 10 regions)
-                // This ensures progress is visible even with many regions
+                // Update progress at regular intervals (every ~10% or at least every 10 regions)
                 let update_interval = (total_regions / 10).max(1);
                 if regions_done.is_multiple_of(update_interval) || regions_done == total_regions {
                     let progress = 90.0 + (regions_done as f64 / total_regions as f64) * 9.0;
@@ -231,6 +125,123 @@ impl<'a> WorldEditor<'a> {
 
         save_pb.finish();
     }
+
+    /// Saves a single region to disk.
+    ///
+    /// This is extracted to allow streaming mode to save and release regions one at a time.
+    fn save_single_region(
+        &self,
+        region_x: i32,
+        region_z: i32,
+        region_to_modify: &super::common::RegionToModify,
+    ) {
+        let mut region = self.create_region(region_x, region_z);
+        let mut ser_buffer = Vec::with_capacity(8192);
+
+        for (&(chunk_x, chunk_z), chunk_to_modify) in &region_to_modify.chunks {
+            if !chunk_to_modify.sections.is_empty() || !chunk_to_modify.other.is_empty() {
+                // Read existing chunk data if it exists
+                let existing_data = region
+                    .read_chunk(chunk_x as usize, chunk_z as usize)
+                    .unwrap()
+                    .unwrap_or_default();
+
+                // Parse existing chunk or create new one
+                let mut chunk: Chunk = if !existing_data.is_empty() {
+                    fastnbt::from_bytes(&existing_data).unwrap()
+                } else {
+                    Chunk {
+                        sections: Vec::new(),
+                        x_pos: chunk_x + (region_x * 32),
+                        z_pos: chunk_z + (region_z * 32),
+                        is_light_on: 0,
+                        other: FnvHashMap::default(),
+                    }
+                };
+
+                // Update sections while preserving existing data
+                let new_sections: Vec<Section> = chunk_to_modify.sections().collect();
+                for new_section in new_sections {
+                    if let Some(existing_section) =
+                        chunk.sections.iter_mut().find(|s| s.y == new_section.y)
+                    {
+                        // Merge block states
+                        existing_section.block_states.palette = new_section.block_states.palette;
+                        existing_section.block_states.data = new_section.block_states.data;
+                    } else {
+                        // Add new section if it doesn't exist
+                        chunk.sections.push(new_section);
+                    }
+                }
+
+                // Preserve existing block entities and merge with new ones
+                if let Some(existing_entities) = chunk.other.get_mut("block_entities") {
+                    if let Some(new_entities) = chunk_to_modify.other.get("block_entities") {
+                        if let (Value::List(existing), Value::List(new)) =
+                            (existing_entities, new_entities)
+                        {
+                            // Remove old entities that are replaced by new ones
+                            existing.retain(|e| {
+                                if let Value::Compound(map) = e {
+                                    let (x, y, z) = get_entity_coords(map);
+                                    !new.iter().any(|new_e| {
+                                        if let Value::Compound(new_map) = new_e {
+                                            let (nx, ny, nz) = get_entity_coords(new_map);
+                                            x == nx && y == ny && z == nz
+                                        } else {
+                                            false
+                                        }
+                                    })
+                                } else {
+                                    true
+                                }
+                            });
+                            // Add new entities
+                            existing.extend(new.clone());
+                        }
+                    }
+                } else {
+                    // If no existing entities, just add the new ones
+                    if let Some(new_entities) = chunk_to_modify.other.get("block_entities") {
+                        chunk
+                            .other
+                            .insert("block_entities".to_string(), new_entities.clone());
+                    }
+                }
+
+                // Update chunk coordinates and flags
+                chunk.x_pos = chunk_x + (region_x * 32);
+                chunk.z_pos = chunk_z + (region_z * 32);
+
+                // Create Level wrapper and save
+                let level_data = create_level_wrapper(&chunk);
+                ser_buffer.clear();
+                fastnbt::to_writer(&mut ser_buffer, &level_data).unwrap();
+                region
+                    .write_chunk(chunk_x as usize, chunk_z as usize, &ser_buffer)
+                    .unwrap();
+            }
+        }
+
+        // Second pass: ensure all chunks exist
+        for chunk_x in 0..32 {
+            for chunk_z in 0..32 {
+                let abs_chunk_x = chunk_x + (region_x * 32);
+                let abs_chunk_z = chunk_z + (region_z * 32);
+
+                // Check if chunk exists in our modifications
+                let chunk_exists = region_to_modify.chunks.contains_key(&(chunk_x, chunk_z));
+
+                // If chunk doesn't exist, create it with base layer
+                if !chunk_exists {
+                    let (ser_buffer, _) = Self::create_base_chunk(abs_chunk_x, abs_chunk_z);
+                    region
+                        .write_chunk(chunk_x as usize, chunk_z as usize, &ser_buffer)
+                        .unwrap();
+                }
+            }
+        }
+    }
 }
 
 /// Helper function to get entity coordinates

src/world_editor/mod.rs

@@ -33,6 +33,7 @@ use std::collections::HashMap;
 use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
+use std::sync::Arc;
 
 #[cfg(feature = "gui")]
 use crate::telemetry::{send_log, LogLevel};
@@ -71,7 +72,7 @@ pub struct WorldEditor<'a> {
     world: WorldToModify,
     xzbbox: &'a XZBBox,
     llbbox: LLBBox,
-    ground: Option<Box<Ground>>,
+    ground: Option<Arc<Ground>>,
     format: WorldFormat,
     /// Optional level name for Bedrock worlds (e.g., "Arnis World: New York City")
     bedrock_level_name: Option<String>,
@@ -122,13 +123,13 @@ impl<'a> WorldEditor<'a> {
     }
 
     /// Sets the ground reference for elevation-based block placement
-    pub fn set_ground(&mut self, ground: &Ground) {
-        self.ground = Some(Box::new(ground.clone()));
+    pub fn set_ground(&mut self, ground: Arc<Ground>) {
+        self.ground = Some(ground);
     }
 
     /// Gets a reference to the ground data if available
     pub fn get_ground(&self) -> Option<&Ground> {
-        self.ground.as_ref().map(|g| g.as_ref())
+        self.ground.as_deref()
     }
 
     /// Returns the current world format
@@ -150,6 +151,19 @@ impl<'a> WorldEditor<'a> {
         }
     }
 
+    /// Get the ground level at a specific world coordinate (without any offset)
+    #[inline(always)]
+    pub fn get_ground_level(&self, x: i32, z: i32) -> i32 {
+        if let Some(ground) = &self.ground {
+            ground.level(XZPoint::new(
+                x - self.xzbbox.min_x(),
+                z - self.xzbbox.min_z(),
+            ))
+        } else {
+            0 // Default ground level if no terrain data
+        }
+    }
+
     /// Returns the minimum world coordinates
     pub fn get_min_coords(&self) -> (i32, i32) {
         (self.xzbbox.min_x(), self.xzbbox.min_z())

tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Arnis",
-  "version": "2.4.0",
+  "version": "2.4.1",
   "identifier": "com.louisdev.arnis",
   "build": {
     "frontendDist": "src/gui"
@@ -16,7 +16,7 @@
         "minWidth": 1000,
         "minHeight": 650,
         "resizable": true,
-        "transparent": true,
+        "transparent": false,
         "center": true,
         "theme": "Dark",
         "additionalBrowserArgs": "--disable-features=VizDisplayCompositor"