UV or not UV unwrap when exporting models from Blender to Unreal: when and why

[cyaoeu]

@csimeon;729580

Blender screenshots of the two channels of UV maps

Difuse UV :

Lightmpas UV : all coplanar faces are individual UV islands, with padding around them

And UE4.16 screenshots :

Lightmap resolution 128: scragly shadow edges baked but the corners are a little curved, “softer” than they should

Lightmap resolution 1024: clean shadow edges baked and sharp corners

Did you test a version with autogenerated lightmaps from UE4? I made a similar mesh to yours and ended up with this which basically looks the same but wastes less space.

Which basically means you would get it for free (from the normal UVs).