“Stop trying to make micro roughness happen, it’s not gonna happen!”
Seriously, here is some explanation from Thea about the effect:
Micro roughness in Thea basically implements a physically-based approach on how roughness changes with the viewing angle. In many cases, this effect can be seen on metals (that we have chosen for the article here) but also on other materials (for example plastics).
It’s a viable phenomenon to portray in any case.