It is proved that analytically aproximating rough surface interaction with light using microfacet theory, it is possible to obtain geometrically accurate results as long as wave length is smaller than the rootmean square surface roughness.1
Interactive 3d model displays incident (inward black arrow) and reflected (outward light arrow) light beams and colormaps reflection intensity of the light on the hemisphere. Linear colormapping according to light intensity is following:
| Intensity | Color |
| 0.0 | Blue |
| 0.5 | Green |
| 1.0 | Red |
A key observable characteristic is the off-specular maxima, meaning that the maximum intensity of the reflected light does not coincede with direction of the reflected beam.
References:
[1] Torrance, K. E., & Sparrow, E. M. (1967). Theory for off-specular reflection from roughened surfaces. Journal of the Optical Society of America, 57(9), 1105–1114. https://doi.org/10.1364/JOSA.57.001105