Lightmap UV pack is leaving huge gaps in uv layout

I’m trying to unwrap this scene for lightmap baking. I’ve selected everything, entered edit mode, made sure the materials have the lightmapsUvs layer selected and tried to unwrap with Lightmap Pack. None the less, I’m getting huge holes in my UV layout. What is happening? Why is there so much empty space?

bake_unwrap_problem.zip (1.3 MB)

Okay, I’ve just realized that most of that blank space is actually very tiny triangles with a lot of space between them. So I guess what I really need is for the lightmap pack to not break my model into so many pieces.

If you want to bake lightmaps, I would suggest using “smart uv project” rather than “lightmap”. Then, you can use “pack islands”, and if you use Blender 3.6 or later, you will get a pretty good packing even with the weird shapes generated by smart unwrap.

Lightmap projection separates each face individually. This would work pretty well for the more traditional use of lightmaps (old games where the environments are made of cubes), but it might leave too many seams in a more modern and high-res model.

In any case, you will have to adjust the “margin” setting when unwrapping or packing, as it controls the distance between islands.

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