Material surface roughness. Specifies the relative roughness of the material surface.
rough= * val *
Surface roughness (0…100 percent) or -1 to select the default roughness.
Used to control the 3D reflection render effect. Lower roughness values typically produce smoother reflection effects; higher values cause randomization and scattering of the reflected image.
Each material type ( type= ) defines a minimum and a maximum reflection render effect based on roughness. For some material types (e.g. wall paper), rough= has hardly any impact on the appearance of the reflection, while for other material types (e.g. stone or ceramic), the effect is substantially more pronounced.
rough=-1 sets the roughness to a server-internal default value (40% for typical material types).
Material attribute. Ignored if the vignette has no 3D reflection capability, if the target object does not have 3D geometry associated with it, or if the target object is not reflecting any other objects in the scene.
catalog::Roughness if the material is based on a catalog entry, otherwise approximately 40%.