I have a problem which only recently came up in a scene I am building. Parts of messhes seem to randomly appear black as though they are unlit. In the attached you can see the identical model(the arch) renders correctly in one case, but not the other. When I simply cut and paste these arch meshes into a new empty scene, they render correctly. I am using precomputed GI but using Baked or Precomputed Realtime or even turning off GI altogether makes no difference. It seems as though parts of the mesh aren’t receiving indirect illumination. With an unobstructed Directional Light, they render fine. I’ve also tried simply cranking up Ambient and Indirect Intensity but that has no effect.
Could this have something to do with my scene complexity?
I think it’s possible that in whatever program you used to create the mesh, the normals were flipped the wrong way. This would make the underside of the mesh be visible but the part you want to see show up as black.
I’m editing my reply since I think I found an answer(8 hours later)!!
Pretty sure it has something to do with Preserve UVs and-or ‘Auto UV Max Angle’ in Lighting>Object.
I had Preserve UVs checked before, I tried unchecking and increased the angle to120. Checking ‘Important GI’ has no effect.
