I've created a very simple model in blender, exported it as FBX and imported in Unity. When I generate light maps on unity I got these strange artifacts (check the images attached here). I've verified the normals and they seems to be correct, the model has been exported with rotation and scale set to 0... any idea where those artifacts are coming from?
Hello I was able to fix this issue. Actually the problem was related to the UVs. For this model I had some overlapping UVS and since I haven't selected the option to generate UV lightmap from Unity the final lightmaps were a mess.
You have three options to fix this issue:
1) Avoid overlapping UVs
2) Create a new UV channel from your 3d editor annd be sure that those UVs don't overlap. unity will automatically pick the second channel for the lightmap and uses the first channel for texture etc.. (I'm not sure about that but this is what I'm reading... I can't find it in the documentation though, please confirm that in case!)
3) With the model selected in unity go to the inspector and select "Generate lightmap UVs" unity will generate a new uv set for lightmap for you (this solution for me doesn't work really well... I choosed option 1.