This was the main topic of my presentation at the Metaverse Standards forum.
Compression and quantization technics have been used to keep GS size under control.
Regarding colors, IIRC Compressed PLY from supersplat have more range than SPZ.
Color conversion between format can be problematic as well. I remember getting lower contrasts because a conversion was a bit problematic.
Without good references (standard), this will still be problematic.
This said, It’s always possible to try to improve rendering quality. Usually, when it’s possible, I compare the shaders to check I didn’t miss something. Using Renderdoc or Spector JS.
Another solution I’m just thinking is to generate a reference, export it and see how it behaves in other rendering engine.
It’s possible with Babylon to generate a complete GS, set splat color/position and export it. For example, generate splat with a color gradient and see if a screen capture gives the same colors.
This is a good opportunity to work on rendering quality for Babylon 9.