---
license: mit
tags:
  - onnx
  - image-to-3d
  - 3d-reconstruction
  - triplane
  - qtmesheditor
library_name: onnx
pipeline_tag: image-to-3d
---

# TripoSR — ONNX export

**ONNX re-export of [stabilityai/TripoSR](https://huggingface.co/stabilityai/TripoSR)**
(Tripo AI + Stability AI — MIT code + MIT weights): single-image → 3D
reconstruction via a triplane radiance field. All credit for the original
weights goes to Tripo AI and Stability AI.

Exported for **[QtMeshEditor](https://github.com/fernandotonon/QtMeshEditor)**
(epic #764), powering `qtmesh generate3d`, the Inspector's **AI: Image → 3D**
section, and the `generate_mesh_from_image` MCP tool — local inference via
ONNX Runtime, with surface extraction done by a native marching-cubes
implementation (upstream's `torchmcubes` is torch/GPU-only).

> The files QtMeshEditor downloads at runtime live in the shared
> [`fernandotonon/QtMeshEditor-models`](https://huggingface.co/fernandotonon/QtMeshEditor-models)
> repo under `triposr/`. This repo is the standalone model card + mirror.

## Files

| file | role |
|---|---|
| `triposr_encoder.onnx` | fp32 encoder (best quality, ~1.7 GB): `image [1,3,512,512]` → `scene_codes [1,3,40,64,64]` (triplane) |
| `triposr_encoder_int8.onnx` | int8 encoder tier (~430 MB, slight quality loss) |
| `triposr_decoder.onnx` | per-point field decoder: `scene_codes` + `points [1,P,3]` → `density [1,P,1]`, `color [1,P,3]` |

An fp16 tier is deliberately absent: TripoSR's attention has a hardcoded
Cast-to-float32 that the ONNX fp16 converters cannot rewrite.

## Inference contract

- Input image: 512×512 RGB in `[0,1]`, subject isolated (upstream composites
  over gray-128 and re-pads the foreground to a 0.85 ratio; QtMeshEditor uses
  U²-Net for background removal first).
- Query the decoder in **chunks** — generating the full `res³` grid up front
  OOMs at high resolutions.
- Surface = marching cubes on `density − threshold` at iso 0, threshold 25.0,
  within radius 0.87. The field is inside-positive; emit flipped winding
  (`v0,v2,v1`) to keep faces outward.
- Output is not +Y-up: bake −90°X then +90°Y to stand the model upright
  facing forward.
- The decoder's colour output can also be used as an image-conditioned colour
  field for texture baking (per-texel queries after a UV unwrap).

## Reproducing

`scripts/export-triposr-onnx.py` in the QtMeshEditor repo (one-time, offline;
`transformers==4.35.0`, `torchmcubes` stubbed, frozen ViT positional
encoding; emits the int8 variant unless `--no-quant`).

## License

MIT (same as the upstream code and weights). Credit: Tripo AI + Stability AI.