Hello! I’m using Unity 5.0.0p2 for now and I have big problems with lightmapping. I made a simple model in blender and imported it into Unity. Realtime light and shadows more or less normal, but when I try to bake light (Light set to bake, and Ambient GI set to bake), I get very strange artifacts and errors in Console. What can I do to avoid this problem?
I just dealt with this very issue, except my files were coming from Maya.
On the offending meshes, in your modeling app, check to see if they have UVs that overlap.
In my case, I had made my own 2nd UV set (specifically for the lightmaps, instead of relying on Unity to generate the UVs). On the problematic meshes, sure enough, I had faces that were laid out on top of each other. I didn’t notice because in 2d (in the UV editor), the mesh looked great.
Separating all faces of the 2nd UV set (lightmap UVs) guaranteed that Unity wouldn’t try to bake lighting onto the same faces with different lighting. Generally, that’s what those pixelated areas are caused by.
NOTE: The first UV set can have overlapping faces (sharing areas of a diffuse map, for example) with no major problems.