Path tracing with colors still presents some challenges. Most mainstream renderers use RGB model, but of course real world has the full EM spectrum. For exampl

Path tracing with colors still presents some challenges. Most mainstream renderers use RGB model, but of course real world has the full EM spectrum. For example for the Cornell box scene, imagine that the wall was pure green material and the box pure yellow material. Then there shouldn't be that visible secondary bounce, but with naive RGB path tracing there would be, because it wouldn't be able to distinguish between pure yellow and mixed yellow. In practice I would expect the effect to be pretty subtle in most scenes, but e.g. scenes lit by sodium streetlights could have stark difference. For example something like https://commons.m.wikimedia.org/wiki/File:Red_and_black_cars_under_low_pressure_sodium_lamps.jpg#mw-jump-to-license https://commons.m.wikimedia.org/wiki/File:Red_and_black_cars...