Colors off

[ladzin]

I'm exporting .ply files from my training scripts using the gsplat library ( https://docs.gsplat.studio/main/apis/rasterization.html ). The files load correctly e.g. in SuperSplat, but in GSOPs I'm seeing some strange differences in colors when rendered in Houdini. I tried disabling the "OpenColorIO" but that only made it worse. I'm optimizing just RGB colors (no SH), they're going through sigmoid activation -- not sure what format is GSOP assuming on input...

[david-rhodes]

@ladzin Do you have images for comparison? The base color is directly converted from the .ply file. Here is the VEX used to generate the base color (Cd) and Alpha, based on the original Inria implementation:

// https://github.com/graphdeco-inria/gaussian-splatting/blob/2eee0e26d2d5fd00ec462df47752223952f6bf4e/utils/sh_utils.py

float SH_C0 = 0.28209479177387814;
float r = 0.5 + SH_C0 * f@f_dc_0;
float g = 0.5 + SH_C0 * f@f_dc_1;
float b = 0.5 + SH_C0 * f@f_dc_2;
v@Cd = set(r, g, b);

float alpha = (1 / (1 + exp(-f@opacity)));
f@Alpha = alpha;

[david-rhodes]

@ladzin did you resolve this?

I had another thought: we don't yet support rotation of models (it breaks the view dependent colors/spherical harmonics). Any chance you transformed your model?