---
license: cc-by-4.0
task_categories:
  - other
  - image-segmentation
  - robotics
tags:
  - topology
  - 3d-object
  - step
  - cad
  - industrial
  - grasp-planning
  - synthetic
size_categories:
  - n<1K
---

# Huhb3D Fastener & Bearing Topology Dataset

STEP topology annotated dataset for 5 fastener and bearing components with per-face semantic labels. Includes ConcaveFeature_Hole, ConvexFeature_Bolt, and Fillet labels for robotic pick-and-place.

## What Makes This Dataset Unique

This is the **only publicly available dataset** that provides STEP-parsed per-face topology labels
for industrial CAD models. Unlike mesh-only datasets, our topology annotations are derived directly
from the STEP B-Rep structure using OpenCascade, providing:

- **Per-face semantic labels**: Each mesh face is classified into one of 15 topology categories
- **STEP source files**: Original parametric CAD models for precise geometry queries
- **Robotic grasp planning**: Topology labels enable grasp strategy selection by face type
- **6DoF pose estimation**: Face-level annotations support pose refinement algorithms

## Overview

- **5** industrial mechanical parts
- **116** total B-Rep faces
- **14506** total mesh triangles
- **12** topology categories with per-face semantic labels
- Industry: **Fastener & Bearing Manufacturing**
- Source models: STEP (ISO 10303-21) CAD files

## Directory Structure

```
Huhb3D-Fastener-Topology/
  README.md
  LICENSE
  DATASET_METADATA.json
  checksums.sha256
  source_step/
    hex_bolt.step
    ...
  objects/
    hex_bolt/
      topology_labels.json       # Per-triangle topology labels
      topology_summary.json      # Topology statistics summary
      grasp_recommendations.json # Grasp recommendations (if available)
    ...
```

## Object List

| Object | Faces | Triangles | STEP | Grasp | Topology Categories |
|--------|-------|-----------|------|-------|---------------------|
| hex_bolt | 17 | 634 | ✓ | ✓ | Boss, Chamfer, HorizontalPlane, LateralPlane_Z, NearHorizontal, NearLateral_X, NearLateral_Z |
| bearing_block | 29 | 3892 | ✓ | ✓ | Boss, ConcaveFeature_Hole, ConvexFeature_Bolt, FreeSurface, HorizontalPlane, LateralPlane_X, LateralPlane_Z |
| bearing_small | 35 | 4928 | ✓ | ✓ | Boss, ConcaveFeature_Hole, ConvexFeature_Bolt, Fillet, FreeSurface, HorizontalPlane, LateralPlane_X, LateralPlane_Z |
| bearing_medium | 29 | 3892 | ✓ | ✓ | Boss, ConcaveFeature_Hole, ConvexFeature_Bolt, FreeSurface, HorizontalPlane, LateralPlane_X, LateralPlane_Z |
| coupling | 6 | 1160 | ✓ | ✓ | Boss, ConcaveFeature_Hole, FreeSurface, LateralPlane_Z |

## Topology Categories

| ID | Category | Description | Color |
|----|----------|-------------|-------|
| 0 | FreeSurface | 自由曲面（圆柱面、圆锥面、B样条曲面等） | #7F7F7F |
| 1 | HorizontalPlane | 法线平行于 Z 轴的平面（顶面/底面） | #0000FF |
| 2 | LateralPlane_X | 法线平行于 X 轴的平面（侧面） | #00FF00 |
| 3 | LateralPlane_Z | 法线平行于 Z 轴的竖直平面 | #FF0000 |
| 4 | NearHorizontal | 与水平面倾斜角 <30° 的平面 | #FFFF00 |
| 5 | NearLateral_X | 与 X 侧面倾斜角 <30° 的平面 | #FF00FF |
| 6 | NearLateral_Z | 与 Z 侧面倾斜角 <30° 的平面 | #00FFFF |
| 8 | ConvexFeature_Bolt | 凸起圆柱特征（螺栓凸台、销钉、轴段） | #7F00FF |
| 9 | ConcaveFeature_Hole | 凹陷圆柱特征（孔、内腔、凹槽） | #007FFF |
| 11 | Boss | 凸起圆柱台（安装凸台、垫台） | #00CC66 |
| 12 | Chamfer | 两个面之间的倾斜过渡边 | #CC6600 |
| 13 | Fillet | 圆角过渡边（倒圆角） | #6600CC |

### Grasp Recommendations

Some objects include `grasp_recommendations.json` with pre-computed robotic grasp poses.
These files are generated by the `grasp_recommendations.py` module and contain:
- Recommended grasp approach directions
- Gripper opening widths
- Grasp quality scores

## Data Format

### topology_labels.json

Per-object file containing:
- `source_file`: Original STEP file name
- `total_triangles`: Total number of mesh triangles
- `total_faces`: Total number of B-Rep faces
- `shape_bounds`: Bounding box [xmin, ymin, zmin, xmax, ymax, zmax]
- `category_names`: Mapping from category ID to name
- `triangle_labels`: Array of category IDs, one per triangle
- `faces`: Array of face objects with:
  - `face_id`, `geom_type`, `category_id`, `category_name`
  - `area`, `triangle_count`, `triangle_start`
  - `extra`: Optional dict with `radius`, `axis_direction`, `normal`

### topology_summary.json

Per-object file containing:
- `source_file`, `total_faces`, `total_triangles`, `shape_bounds`
- `categories`: Dict mapping category ID to name, face_count, triangle_count, total_area

### grasp_recommendations.json (optional)

Per-object file containing pre-computed grasp poses with approach directions,
gripper widths, and quality scores.

## Pricing

| License | Price |
|---------|-------|
| Personal / Academic | **$39** |
| Commercial | **$99** |

All prices in USD. Commercial license permits use in proprietary products.

## Citation

If you use this dataset in your research, please cite:

```bibtex
@dataset{huhb3d_fastener_topology,
  title   = {Huhb3D Fastener & Bearing Topology Dataset},
  author  = {Huhb},
  year    = {2026},
  version = {1.0.0},
  url     = {https://github.com/huhb-ai/Huhb3D-Topology-Dataset}
}
```

## License

- **3D Models**: CC0 (Public Domain) — original creations, no restrictions
- **Dataset** (annotations, metadata, packaging): **CC-BY-4.0** — attribution required

You are free to share and adapt for any purpose, including commercially, as long as
appropriate credit is given.

See [LICENSE](LICENSE) for the full license text.

## Contact

- Email: huhb_ai@outlook.com
- GitHub: https://github.com/huhb-ai