Indoor scenes reconstructed from single 360° walking videos (Insta360 → equirectangular 3840×1920).
Pipeline: frame extraction → spherical SfM (OpenSfM) → MVS dense initialization → 3DGS training.
The cafe scene is the density-optimized run (3M init points), reaching held-out PSNR 20.95 dB — first break past the 20 dB ceiling.
How many initial points does 3DGS actually need? Same scene, only the MVS dense-init density changed.
| init points | final gaussians | held-out PSNR | verdict |
|---|---|---|---|
| 400k | 367k | 19.55 dB | too sparse |
| 1.5M | 1.22M | 20.87 dB | sweet spot |
| 3M | 2.27M | 20.95 dB | saturates (+0.08 dB) |
400k → 1.5M gives +1.32 dB; 1.5M → 3M only +0.08 dB while doubling size and training time. densify/prune absorbs the extra points — the initial cloud just needs to be sufficient, not maximal. (The cafe scene above serves the 3M run.)