You're correct, for what it's worth. I too have always wished that light was modeled based on physics, not on how humans happen to see. Unfortunately the probl

You're correct, for what it's worth. I too have always wished that light was modeled based on physics, not on how humans happen to see. Unfortunately the problem is data acquisition (cameras), and data creation (artists). You need lots of data to figure out e.g. what a certain metal's spectrum is, and it's not nearly as clear-cut as just painting RGB values onto a box in a game engine. For better or worse, all our tools are set up to work in RGB, regardless of the color space you happen to be using. So your physics-based approach would have the monumental task of redefining how to create a texture in Photoshop, and how to specify a purple light in a game engine. I think the path toward actual photorealism is to use ML models. They should be able to take ~any game engine's rendered frame as input, and output something closer to what you'd see in real life. And I'm pretty sure it can be done in realtime, especially if you're using a GAN based approach instead of diffusion models.