# Low-poly scrub bush experiment report

## Outcome

Do not adopt `assets/models/custom/bush_low/bush_low.glb` as the default scrub
edge bush.

The asset successfully reduced geometry cost, but user validation found the
visual result unsatisfactory. The default generator was restored to
`assets/models/custom/bush/bush.glb`.

## Measurements

Commands used during the experiment:

```bash
python3 -m py_compile blender/generate_scene.py
python3 -m unittest blender/tests/test_pure.py
npm run build:area -- --config config/areas/nantaizi-lake-innovation-valley.json --stages blender,cesium,preview
node scripts/glb-digest.js outputs/nantaizi-lake-innovation-valley/nantaizi-lake-innovation-valley.glb --out /tmp/nantaizi-bush-low-glb-digest.json
node scripts/glb-digest.js assets/models/custom/bush/bush.glb --out /tmp/bush-original-digest.json
node scripts/glb-digest.js assets/models/custom/bush_low/bush_low.glb --out /tmp/bush-low-asset-digest.json
```

Low-poly asset geometry:

- Original `bush.glb`: `9.10 MB`, `63,762` vertices, `67,536` indices.
- Experimental `bush_low.glb`: `5.79 MB`, `4,044` vertices, `4,050` indices.
- Texture count stayed at `6`, so file size did not fall proportionally with
  geometry.

Nantaizi rebuild while using `bush_low.glb`:

- `SCENE_DONE.scrub_bushes`: `266`
- GLB nodes: `830`
- Scrub bush nodes: `266`
- Scrub bush shared mesh: `4,044` vertices, `4,050` indices
- GLB size: `27.51 MB`
- Metadata scrub polygons: `5`

## Decision

This proved geometry reduction works, but this particular low-poly model is not
good enough visually. Keep the current density budget and original default bush
asset for now. The next useful direction is a better-authored low-poly bush:
same approximate silhouette/volume as the original, lower geometry, and reduced
or compressed texture payload.