Differences between G8 and G8.1 materials

jwcjaygaines

So I've been going through my models and updating them from G8 to G8.1. My material setup in Blender uses the Diffuse, Normal, Bump, SSS, and Specular maps plugged into slots and woven through some custom node groups I made (Skin Color and Skin Sweat). If one of the needed maps isn't available under a particular model, I will use the Base version's map instead. This is usually with the Bump and Specular maps. G8.1 has a different naming system for their maps, and it's causing me some confusion. The main ones are AO and R; I'm assuming Ambient Occlusion and Roughness. Are these the PBR version of Specular? If so, can I use them in the Specular's slot? I tried reading about Ambient Occlusion, but it only "occluded" my brain, and I still don't understand what the H-E-double-hockey-sticks it does, but I'm guessing it's important.

Richard Haseltine

AO usually measures how inacessible a bit of mesh is - if it is in a fold it will be darker, if it is on a flata rea of skin it will be lighter. It would in theory be used to fake illumination from the geneal (ambient) lighting in a scene, darkening recessed areas reltiave to exposed areas, though Iray doesn't usually want such baked-in trickery. The maps may be used to control some other property that is also dependent on exposure. Roughness would be related to shine, it measures how even a surface is (so a rought surface would tend to have more spread out highlights as different parts face in different directions, rather than a smooth surface which essentially faces one way and either catches light or doesn't).