Splat .ply export not supported by multiple viewers

[robinsonkwame]

Describe the bug

Documentation here states

Nerfstudio’s splat export currently supports multiple third-party splat viewers:

Polycam Viewer

Playcanvas SuperSplat

WebGL Viewer by antimatter15

Spline

Three.js Viewer by mkkellogg

but an exported splat .ply generated from a sample Lion statue video (here) on 2/9 fails to be viewed properly in all 3rd party viewers but Polycam.

To Reproduce
Steps to reproduce the behavior:

1. Download sample Lion statue video (here)
2. run ns-process, ns-train splatfacto, and ns-export
3. Go to each viewer listed above
4. Upload the .ply file, compare results to polycam

Expected behavior
All viewers at least approximately look similar

Screenshots
e.g.,

Polycam

Supersplat

Additional context
Even if Nerfstudio can't support the listed viewer, it would be helpful to describe any transformations and changes to exported splat .ply files that are typically required to be viewable in, say, Supersplat and other viewers. This would support frontend UI development against NerfStudio splat output.

[jb-ye]

Your splat can by rendered in supersplat ( you need to set splat size to 0 on the left panel). You just need to rotate and zoom a bit to see the lion ...

The applied transform was lost in PLY exporter, if you use nerfstudio viewer, it will restore properly and see the lion on the startup frame.

[jb-ye]

But I agree that one should be able to see the "applied transform" and "scale" as metadata from exporter such that, one can use them to generate proper renders in external viewers.

@brentyi Do you think this is worthwhile to add a metadata json to document those information aside PLY exporter.