A .spz or a .ply from Scaniverse, Polycam or any
other splat capture. Prefer the SPZ: it is the same points at a tenth the
size. Nothing is uploaded, it stays in the page.
A .glb from splat2glb --trace-glb holds a cloud
and the outlines traced round it in one file, so it opens on its own.
A traces.json from --trace-out is the outlines
without the cloud, and goes on top of one already open.