Overlapping Lightmaps and resolution

Development Rendering
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1

So on first Build I get an error saying my Lightmaps are overlapping 73%!!
Some googling watched this for a solution UV Lightmap are Overlapping - Resolve issue - UE4 Blueprints - YouTube
Checking the UV in the Mesh Editor I see that the UV index is correctly defined as 1 but my Lightmap index is only 64.
Also a visual inspection of the UV shows nothing overlapping.

So I increase the LM resolution to 1024, do a 2nd build and now get an error saying my Lightmaps are overlapping 4%.

Repeat a 3rd time with LM resolution to 2048 and get an error saying my Lightmaps are overlapping 2%.

My question is

Is 2% overlap acceptable or must it be 0% overlap?

and

How do you achieve 0% overlap without increasing the resolution to unacceptable values?

2

In theory, any amount of lightmap overlapping is “acceptable” as long as you think the mesh looks good. It is just warning you that it thinks your mesh might look ugly because the light maps are on “wrong.” The game will still play fine.

As for fixing it, you seem to have done everything you can engine-side. To my knowledge, having Unreal auto-generate a lightmap and/or setting the resolution higher is pretty much it. If you really need to fix it, you probably need to go into a 3D modeling program and make your own lightmap at this point.