I wonder if it is possible to precompute this in some way? I understand that it's dependent on the angle and position of the camera relative to the surface though so there's probably no way to exactly precompute all possibilities, but maybe it is possible to make some kind of approximation or heuristic? I guess that would just be a regular BRDF without microfacets idk.
I find it very interesting to know that as technology advances there is a higher need for more nuanced reflectance models. We now need to model the characteristic behaviors of
certain types of material and not just the physical laws of surfaces. I think such models will depend on having good BRDF measurements.
Is this some kind of prefiltering? I.e., obtaining an overall distribution of the BRDF over a patch by averaging the microfacets in the patch.