Overlapping UV's

Hey all.

Got a simple model, which I’ve added two UV channels to in max. One has overlapped UV’s for texturing, the other has unique UV’s for lightmap use. Only when I’m using it in a level and baking lightmaps, it tells me “Basket has overlapping UV’s” which is fine (and as expected), but also says “Lightmap UV are overlapping by 65% please adjust content - Enable error coloring to visualize”.

So… a couple questions:

  1. Why is the lightmap overlapping when clearly the UV’s arent (I can look at the second UV channel in model viewer and dont see any overlapping and I redid the second channel UV’s deliberately to avoid it).
  2. How do I enable error coloring? sounds like it might be useful.


Quick update to this. I generated the UV’s for UV0 in Unreal using the automatic generation so that there were not overlaps and the errors went away. So it looks like somehow when calculating the lightmaps it was using UV0 instead of UV1 at least for testing for overlap, which seems a tad weird.

Check mesh “Lightmap coordinate index” value in mesh editor, for UV1 set this value to 1.

Thanks, I was looking at this again and just now noticed that value. I guess because some of my other meshes have unique coordinates it wasn’t an isssue for them, but this one had tiled texture usage and was a problem until I set that value.