Extract an object from a trained 3D Gaussian Splatting scene and export it as a standalone PLY. Open the scene in the viewer, click the object from a few angles, and SAM2 segments those views to identify the object's Gaussians. No source photos are needed.
- A CUDA GPU, Python 3.10–3.12 and the CUDA Toolkit.
- A scene already trained with Graphdeco 3DGS, opened from its
point_cloud.ply. Training is out of scope.
From the repository root, install PyTorch for your CUDA version (the index URL is for CUDA 12.8), then the tool:
python3 -m venv .venv-gpu
source .venv-gpu/bin/activate
pip install --upgrade pip setuptools wheel
pip install torch torchvision --index-url https://download.pytorch.org/whl/cu128
SAM2_BUILD_CUDA=0 pip install --no-build-isolation -r requirements.txt
pip install --no-deps -e .The SAM2 checkpoint (about 300 MB) downloads on first use into ~/.cache/gs-object-extraction/checkpoints/. gsplat compiles its CUDA kernels the first time a scene is opened, which takes a minute or two.
gs-object-extraction-gui [scene.ply]
- Mark views. Press S, click the object, and SAM2 overlays a mask (right-click what it wrongly includes). Enter adds the view. Mark about 16 from around the object, camera low; Mark around does the ring after one view. Click a view in the list to check it, Remove view to drop it.
- Extract. Ctrl+E. The view switches to the object alone.
- Clean up. In the object preview, press S and drag a box or click to select strays (red); X or Delete removes them, Ctrl+Z undoes. Refine refits opacity, colour and size so the object stands solid; set Edge trim first. Revert undoes it.
- Export. Ctrl+Shift+S.
The icons in the top right of the view toggle: Gaussians as blue points, object or scene, white or black background, and a box round the kept Gaussians with its size.
The camera moves as in Isaac Sim.
| Input | Action |
|---|---|
| Alt + left drag / middle drag / right drag | Orbit / pan / look around |
| Alt + right drag, wheel | Zoom |
| Double-click | Rotation centre under the cursor |
| S, Enter, Backspace, Esc | Select mode, add view, undo point, clear points or selection |
| Shift, Ctrl while selecting | Add to, take away from the selection |
| Ctrl+E, Ctrl+Shift+S | Extract, export |
Under Advanced in the Object panel:
- Off-mask limit: lower drops more stray Gaussians, at the cost of thinner edges. Extract again after changing it.
- Edge trim: pulls in Gaussians reaching past the masks;
1.00leaves them. Applies to the finished object and to the export.
Surfaces missing from the source scene cannot be recovered: an object photographed from one side stays hollow on the other.