When MentalRay users talk about 'physical correctness', in most of the cases the usage of DGS (diffuse, glossy, specular) shaders is discussed. Some people say you should use them at least as photon shaders, just because they're fast and, yes, physically plausible. But how do they act differently than the Maya base shaders? If you ever used dgs shaders, you probably asked yourself if it was possible to 'mimic' the dgs behavior somehow - just because they are yet simple, but sometimes very hard to bear with (just think of the glossy reflection samples that cant be set - very annoying). What if we could tell a Maya base shader to act like it's dgs companion?
Let's have a look at how 'different' they actually look (without using photons - we're only out for the regular shading for now). I took a standard phongE material without any highlight or reflection (so actually it acts like a lambert material) for comparison: