PLY vs SPLAT: Gaussian Splatting Format Comparison

Every 3DGS training tool — the original INRIA code, Nerfstudio, gsplat, Polycam, Luma AI — outputs PLY. It stores all Gaussian parameters at full float32 precision: position (3 floats), rotation quaternion (4 floats), scale (3 floats), opacity (1 float), base color (3 floats for SH degree-0), and optionally up to 45 additional spherical harmonics coefficients for higher-order view-dependent color. A typical scene with degree-3 SH uses about 236 bytes per Gaussian.

PLY's strength is completeness: no data is lost, no precision is sacrificed. This makes it the right format for archival, research, editing, and any workflow where you might need to re-process the data. Its weakness is obvious: file sizes are enormous. A room-scale scan (1-2M Gaussians) produces a 200-400 MB PLY. Unsuitable for web delivery, inconvenient for sharing.

SPLAT reduces each Gaussian to exactly 32 bytes by aggressive quantization and data stripping. Position stays at full float32 (12 bytes). Scale is stored as 3× float32 (12 bytes). Color is quantized from float32 SH to 4× uint8 RGBA (4 bytes) — this is where spherical harmonics are lost, replaced by a single averaged color. Rotation is quantized from float32 to 4× uint8 (4 bytes).

The result is about 86% smaller than PLY by stripping spherical harmonics — 32 bytes vs ~236 bytes per Gaussian. And the quality cost is real: without spherical harmonics, scenes lose their photorealistic view-dependent appearance. Glossy surfaces no longer shimmer. Shadows no longer shift color. Materials lose their tangible quality. The scene becomes a uniformly lit 3D photograph rather than an interactive light field.

SPLAT's design made sense in late 2023 when the priority was getting 3DGS into browsers at all. In 2026, with SPZ offering 10x better compression WHILE preserving SH, SPLAT's trade-offs are much harder to justify for new projects.

Both PLY and SPLAT have been superseded by SPZ for distribution use cases. SPZ achieves 10-12x compression over PLY (vs SPLAT's ~7x), preserves spherical harmonics (unlike SPLAT), and is on the Khronos standardization track. A 200 MB PLY becomes 16 MB SPZ — smaller than the ~32 MB SPLAT, and with better visual quality.

Our recommendation: use PLY for archival and editing. Use SPZ for everything else. Only use SPLAT if you specifically need to target a legacy viewer that does not support SPZ. For conversion: polyvia3d.com/splat-convert/ply-to-spz (recommended) or polyvia3d.com/splat-convert/ply-to-splat (legacy compatibility only). See our PLY vs SPZ comparison for a detailed SPZ analysis.