LocalAI/docs/content/features/3d-generation.md

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LocalAI can generate textured 3D meshes from a single conditioning image via the /3d/generations endpoint, powered by the trellis2cpp backend — a C++/GGML port of Microsoft TRELLIS.2 (trellis2.cpp). The output is a binary glTF (.glb) asset with PBR materials.

Generation is image-conditioned only — there is no text-prompt path. Provide a photo or rendering of a single object (ideally on a plain background) and TRELLIS.2 reconstructs a full 3D mesh from it.

Setup

Install a model from the gallery:

local-ai run trellis2-4b          # full pipeline: 1024³ cascade + PBR textures (~18 GB)
# or
local-ai run trellis2-4b-geometry # 512³ untextured geometry only (~7 GB)

The backend detects which component GGUFs are present and degrades gracefully: without the texture models it produces untextured geometry, and without the fine-flow models it falls back to a coarse marching-cubes preview.

API

• Method: POST
• Endpoint: /3d/generations

Request

The request body is JSON with the following fields:

Parameter	Type	Required	Default	Description
model	string	Yes		Model name to use
image	string	Yes		Conditioning image as base64, a data URI, or a public URL
quality	string	No	auto	Mesh pipeline: auto, coarse, 512, or 1024
background	string	No	auto	Background handling: auto, keep, black, or white
step	int	No	12	Flow sampling steps for the shape
texture_steps	int	No	12	Flow sampling steps for the PBR material
cfg_scale	float	No	7.5	Classifier-free guidance scale
seed	int	No	random	Random seed for reproducibility
response_format	string	No	url	url to return a file URL, b64_json for base64 output
params	object	No		Backend-specific string parameters (texture_size, components)

quality selects the mesh resolution: coarse is a fast marching-cubes preview, 512 the fine dual-grid mesh, 1024 the high-resolution cascade (slow — several minutes, roughly 10 GB VRAM), and auto picks the best pipeline the installed model set supports.

background controls solid-background removal on the conditioning image before generation: auto detects border-connected near-black/near-white, keep preserves the image alpha exactly, and black/white force removal of that colour.

Backend-specific params: texture_size (UV-atlas resolution hint when atlas baking is enabled) and components (tiny removes small islands, largest keeps only the biggest connected component, all — the default — keeps everything).

Response

Returns a JSON response using LocalAI's OpenAI-style generation envelope:

Field	Type	Description
created	int	Unix timestamp of generation
id	string	Unique identifier (UUID)
data	array	Array with the generated asset
data[].url	string	URL path to the .glb under /generated-3d (if url)
data[].b64_json	string	Base64-encoded GLB (if response_format is b64_json)

Watertight print remeshing

POST /3d/remesh applies the same post-generation CGAL Alpha Wrap workflow as the trellis2.cpp demo. It accepts multipart/form-data and returns the remeshed GLB directly as model/gltf-binary:

Field	Type	Required	Default	Description
model	string	Yes		Installed TRELLIS.2 model name
mesh	file	Yes		Source GLB produced by TRELLIS.2
detail	float	No	0.5	Smallest preserved detail as a percentage of the source bounding-box diagonal (0.35–2.5)

There is intentionally no independent offset control. The enclosing offset follows the trellis2.cpp demo and is derived as detail / 30; independent tuning tends to produce puffy or degenerate wraps. Lower detail percentages retain finer features but take longer and generally produce more triangles. The output is watertight, oriented, intersection-free, and 2-manifold. For textured sources, LocalAI unwraps the replacement mesh and reprojects its PBR material onto a new UV atlas.

Source GLBs may be up to 512 MiB. This route uses its own upload limit because fine TRELLIS.2 meshes commonly exceed LocalAI's default --upload-limit.

curl http://localhost:8080/3d/remesh \
  -F model=trellis2-4b \
  -F mesh=@generated.glb \
  -F detail=0.5 \
  --output printable.glb

Usage

Generate a 3D model from an image

curl http://localhost:8080/3d/generations \
  -H "Content-Type: application/json" \
  -d '{
    "model": "trellis2-4b",
    "image": "https://example.com/photo-of-a-chair.png",
    "quality": "512"
  }'

The response contains a URL such as /generated-3d/b64123456789.glb; fetch it from the same server. The GLB is standard glTF 2.0 and opens in Blender, three.js, <model-viewer>, and most engines.

Base64 input and output

curl http://localhost:8080/3d/generations \
  -H "Content-Type: application/json" \
  -d "{
    \"model\": \"trellis2-4b\",
    \"image\": \"$(base64 -w0 chair.png)\",
    \"response_format\": \"b64_json\"
  }" | jq -r '.data[0].b64_json' | base64 -d > chair.glb

WebUI

The React UI includes a 3D tab in the Studio (and a /3d page) with an interactive PBR viewer: upload an image, pick the quality, and preview the generated mesh with orbit/pan/zoom and a wireframe toggle. Past generations are kept in the browser (IndexedDB). After generation, a single Detail slider and Apply remeshing button replace the preview with the exact watertight model that the GLB download exports; Show original switches back without regenerating.

Notes

• The 512³ pipeline takes roughly two minutes on a modern GPU; the 1024³ cascade takes around five minutes and needs about 10 GB VRAM plus a temporary host-RAM spike.
• TRELLIS2_DEVICE=cpu forces CPU inference (slow; mainly for debugging).
• The generated mesh has unoriented winding (faithful to TRELLIS.2) and is exported Y-up with vertex-PBR materials; a UV-atlas texture bake can be enabled in the backend via the T2GLB_XATLAS environment variable.