Splat file formats: PLY, SPZ and where they open

Gaussian Splats

Raw PLY is the interchange format and is huge; SPZ is the compressed one. What each is for, and what reads them.

A splat is a list of Gaussians, and the file formats differ mainly in how tightly they pack that list. Three are common: PLY, the raw interchange format; SPZ, a compressed format built for splats; and .splat, a compact format made popular by early web viewers.

What is a PLY splat?

PLY is a general point-cloud format that splat tools adopted from the start: one record per Gaussian, with its position, scale, rotation, opacity and colour coefficients as plain numbers. Nearly every splat tool reads and writes it, which makes it the safe choice for moving a splat between programs. It is also large — a scene of a few million Gaussians easily runs to hundreds of megabytes.

What is SPZ?

SPZ is an open format for Gaussian splats published by Niantic. It quantises and compresses the same data, and its authors describe it as about ten times smaller than the PLY equivalent with virtually no perceptible loss in quality. That is the difference between a file that opens on a phone over a mobile connection and one that does not.

What is a .splat file?

A .splat file stores each Gaussian in a small fixed-size record — position, scale, colour with opacity, and rotation — and drops the view-dependent colour terms PLY carries. It is compact and quick to stream, which is why web viewers adopted it, at the cost of the colour shifting less convincingly as you move.

Which should you use?

  • SPZ for anything delivered to viewers — the web, phones, headsets — where download size decides whether the scene opens at all.
  • PLY when another tool needs the splat and does not read SPZ, or when you want the uncompressed data to edit.

Where do splats open?

Support has spread quickly since 2023:

  • Browsers through WebGL and WebGPU splat renderers, which is how a splat opens from a link.
  • PlayCanvas reads splats natively, and its open-source SuperSplat editor can view and clean them up.
  • Game engines through plugins, for Unity and Unreal among others.

Check the specific tool's current documentation before you commit to a pipeline: splat support is young and changes fast.

Which formats does Zetta 3D produce?

  • Zetta Splat delivers a .splat file.
  • Zetta Splat 2 and 2.1 worlds are kept as SPZ — a standard copy and the full set, chosen when you open the world.
  • From a world, Inspect can export splats as PLY (at full size or reduced to 500K, 150K or 100K splats), a mesh as GLB (textured or with vertex colours), and a collider mesh as GLB for physics. An exported mesh opens in every mesh tool in the Studio.

Sources

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