Collision mesh quality is very poor for indoor room scans — voxel-external-fill appears to leak or produce incomplete geometry

[bentleyer]

Summary

The collision mesh generated by --voxel-external-fill + --voxel-carve + -K for an indoor room scan is extremely poor quality — large chunks of geometry are missing, walls are incomplete, and the overall shape does not resemble the scanned room. The guide (COLLISION.md) suggests this pipeline should work well for interior scenes, but the result is unusable for runtime collision.

Version & environment

• @playcanvas/splat-transform (main branch, cloned locally)
• Windows 11
• Node.js 20 (--max-old-space-size=16384)
• CPU mode

Input

An indoor room scan captured via 3D Gaussian Splatting, saved as .splat format. The scene is a multi-room interior space with standard walls, floors, and ceilings.

Reproduction

node --max-old-space-size=16384 bin/cli.mjs -w \
  "input_indoor.splat" \
  --filter-cluster --seed-pos -37,29,21 \
  --voxel-external-fill --voxel-carve \
  -K \
  "output.voxel.json"

<img width="1651" height="1022" alt="Image" src="https://github.com/user-attachments/assets/68c1c3ee-dcb4-4854-a189-6fcafb0cda47" />

<img width="1643" height="960" alt="Image" src="https://github.com/user-attachments/assets/343fb0b1-7c8e-4897-88b0-1e98e3917e5b" />

[slimbuck]

Hi @bentleyer,

There are two things:

• if the fill size is too small it'll fill the interior. try increasing external fill size
• note that all processing happens in opengl/playcanvas coordinate system, not PLY. check that your seed position is correct.

If you're able to share the scene with me I can also investigate.

[bentleyer]

Thanks @slimbuck for the quick response!

I've uploaded a test scene here: https://github.com/bentleyer/splat/blob/main/test.zip

[slimbuck]

Thanks, sorry busy day yesterday. If you load the .splat into editor you'll see the scene is rotated on it's side.

So at the very least you'll need to rotate the input .splat. I would suggest loading the model into supersplat editor and orientating it there, then exporting to PLY. Use the editor to get the seed position too.