[corysama]

There have been decades of research into generalized BRDF measurement of real materials. Usually it starts with capturing calibrated images of the combination of all camera angles and all lighting angles on the hemisphere.

https://www.researchgate.net/figure/Picture-of-the-BRDF-meas...

https://www.iosb.fraunhofer.de/en/projects-and-products/sig_...