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license: cc-by-4.0
tags:
- mesh-segmentation
- part-segmentation
- point-cloud
- building
- architecture
- onnx
- 3d
- qtmesheditor
library_name: onnx
pipeline_tag: other
---
# QtMeshEditor — Building Part Segmentation
A point-cloud part-segmentation network (PointNet++-style) that labels each
point of a **building** mesh as `wall`, `roof`, `window`, `door`, `chimney`,
or `foundation`, exported to **ONNX** for local inference via ONNX Runtime.
One of the category-specialised segmentation models built for
**[QtMeshEditor](https://github.com/fernandotonon/QtMeshEditor)** (epic #818,
Track B2) — a free, open-source 3D mesh & animation editor. The app
auto-detects the mesh category with a companion
[point-cloud classifier](https://huggingface.co/fernandotonon/QtMeshEditor-mesh-segmentation-category)
and dispatches to this model for buildings; siblings:
[body](https://huggingface.co/fernandotonon/QtMeshEditor-mesh-segmentation),
[vegetation](https://huggingface.co/fernandotonon/QtMeshEditor-mesh-segmentation-vegetation),
[vehicle](https://huggingface.co/fernandotonon/QtMeshEditor-mesh-segmentation-vehicle).
Aggregate download source used by the app:
[QtMeshEditor-models](https://huggingface.co/fernandotonon/QtMeshEditor-models)
(`segment/meshseg_building.onnx`).
## Model
- **Input:** a sampled point cloud `float32 [1, N, 3]` (normalised to a centred
unit box; +Y up).
- **Output:** per-point class logits over 7 channels
(`unknown, wall, roof, window, door, chimney, foundation`); argmax → label,
scattered back to mesh vertices/faces by nearest sampled point.
- **Architecture:** shared per-point MLP + two kNN local-aggregation blocks
(in-graph `cdist`+`topk`, ONNX-exportable) + a global max-pooled feature;
~0.78 MB. Trained at the app's inference sample size (4096 points).
## Training data & license
Trained **from scratch, 100% on procedurally generated synthetic buildings we
own** (no third-party data at all): parametric houses / towers / huts with
gable, pyramid, and flat roofs (triangle/quad surface patches), proud window
panes in rows, doors, chimneys, and foundation slabs — labels are exact by
construction. Weights released under **CC-BY-4.0**; please credit
*QtMeshEditor*.
## Evaluation
- Held-out synthetic validation accuracy: **86.9%** (per-point, unknown
masked). Real-world CC0 building kits are the planned next data slice
(mined via submesh/material-name labels).
## Reproducing
`scripts/export-meshseg-onnx.py --category building` in the QtMeshEditor repo
(one-time, offline; the app never runs Python). Strategy + roadmap:
`docs/MESH_SEGMENTATION_STRATEGY.md`.
## Versions
- **v1.0.0** (current) — initial synthetic-only release (#818 Track B2).
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