Hi guys, I’m having an issue with one of my objects when importing everything looks fine until I build. Then it displays like the image below where the windows and some panels are blacked out and looks very off:
I then get an error message saying
Object has overlapping UV’s
Lightmap UV’s are overlapping by 78.7%
I’m using Blender to create my object and nothing is touching in my UV map, so I’m not sure how they are overlapping. This is what my UV map looks like:
For lightmap you should have a second set of UVs.
If you dont have the second UV set ue4 generates one.
Maybe the second set is overlapping?
have you tried opening the mesh in ue4 and looking at the uv maps there to see what is overlapping?
I guess Unreal generated the second (lightmap) uv, otherwise the whole mesh would be black…
Maybe you have duplicated/overlapping faces in your mesh!
I know this was not the question but it’s kind of impossible to get a nice rendering result with keeping your whole building as one mesh! If you want a nice, realistic result you would have to have a huuuge lightmap (even 4096 would be enough I think) with a mesh like this! …you should break up your mesh to smaller pieces and have separate lightmaps… (if you look at your render, even at the clean parts, where you have shadow blocks they are in “abstract” shapes: there is not enough lightmap resolution to visualize it properly…)
Do you have any modifiers enabled? If you were using the mirror modifier this will cause overlapping UVs on both your standard UV and lightmap.
Mine was the same, but I found out the problem was related to the windows which I had mapped separately to save space for the window texture so it had a separate UV map and the mesh was not joined together for final, the building and windows had to be handled differently, so I created a UV Map for the Building, a UV Map for the Windows, I combined those separated mesh portions together into a single mesh which also brings together both separate UV Maps into the one mesh, and then created a UV Map for the Light Map by unwrapping the entire mesh.
The only problem I experienced after that was that during import I had to identify visually through comparison in both Blender (UV/Image Editing) and UE4 (Mesh Editor) exactly the UV Maps to identify the Lightmap Index number to set so the engine knows which UV Map to use for the Lightmap. Even though there was 3 UV Maps it was not in order, in Blender the last UV map added was 3, so it should have been an index of 2, but nope, the loaded UV map was UV 1, so I had to set it the Lightmap Index to 1.
After that it builds with no problem.
