So I know that the diffuse roughness value of the diffuse bsdf activates the oren-nayer model for higher roughness values and I also know that the specular roughness values do not represent the diffuse roughness values. Is there a way to convert specular roughness values to diffuse roughness values or are those two values completely independant of each other. This thread What does the Roughness setting on a diffuse shader do? suggests a formula like this: diffuse_roughness=specular_roughness/3 but it also mentions that this formula was just simply eye balled rather than derived through physical models.

  • $\begingroup$ I don't think specular is related to roughness, it relates to ior,docs.blender.org/manual/en/3.0/render/shader_nodes/shader/… $\endgroup$
    – NatureK
    Mar 11, 2022 at 16:03
  • $\begingroup$ Yes and no. Yes in the sense that specular reflection is somthing completely unrelated to roughness and no in the sense that this wasn't what I asked. If it clarifies a little some refer to specular roughness also to glossy roughness, so the roughness value on the gloosy or anisotropic bsdfs. $\endgroup$ Mar 12, 2022 at 15:04


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