Convert with your eyes open
The splat formats are not interchangeable. Converting a PLY to .splat makes the file eleven times smaller and throws away everything that made the capture look real; converting it to SPZ makes it ten times smaller and keeps almost all of it. Most converters do not tell you which of those just happened. This one shows the cost of every target before you pick, and counts the actual damage afterwards.
What each format costs
- PLY (3D Gaussian Splatting) — the interchange format. Float32 throughout, every spherical-harmonic band, and by far the largest file. Converting to PLY is lossless.
- SPZ — Niantic's gzip-compressed container. Positions land on a fixed-point grid of about a quarter of a millimetre, scales are stored as a byte covering
exp(-10)toexp(5.94), the base colour as a byte covering ±3.33, and each higher coefficient as a byte covering ±1. In practice the result is visually indistinguishable, but a real capture usually has a handful of splats outside those ranges, and this tool counts them. - KSPLAT — the format of the GaussianSplats3D viewer. Written at compression level 0, which every reader accepts and which caps the spherical-harmonic degree at 2.
- SPLAT — 32 bytes per splat, no header, supported everywhere. It stores only the evaluated base colour, so every spherical-harmonic band is lost and the scene renders flat.
- SOG — read, but not written. Writing one needs a lossless WebP encoder; the browser's own encoder is lossy and would corrupt the quantised values, so the option is absent rather than silently wrong.
Capping the spherical-harmonic degree
Dropping band 3 removes 21 of a splat's 45 coefficients and typically halves the file, while costing far less visually than dropping the splat count. The degree slider lets you make that trade deliberately, and the size table updates as you drag it.
After the conversion
The report is measured, not assumed: how many splats had a scale or a colour outside the target's range, how many spherical-harmonic bands were dropped, and how the output size compares with the input. Everything runs in your browser — the capture is never uploaded.
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