Hello,
Does overlapping similar parts of model make any impact on lighting in UE5 ?
I am asking about all kinds of lighting and any type.
I have 2 types of overlaping meshes:
-A,B,C is on mirror.
-D,E,F is on Array.
I am trying to prepare my 3d asset perfect way.
I use blender + substance painter.
I made seams on my 3d asset and made UV maps properly.
There are a lot of parts that are similar in my asset that could overlap to save space on my uv map.
I kindly ask for help.
I have noticed issues with using Ctrl+M for mirroring as for lighting as opposed to using the mirror modify, I don’t know too much, but it has caused me issues in the past, something to note, I guess. Probably an issue exclusive to me, (I’m not a 3d modeler.) But either way, hope it helps! 
Hi. If you want to use static(baked) lighting on your mesh you have to make a 2. UV channel that can store the lighting information. This secound UV should not overlap.
Further, your cusrom light UVs should be just right for the ^2 texture size you want to use.
I would suggest starting them off in a 256x256 texture, aligning the island vertex with the center of each pixel.
This will allow you to scale up to larger texture sizes and prevent most artefacts due to the mip process.
Its bit a “catch all” and structures that arent on the same pixel line (anything orthogonal?) Is going to either need special attention or has to be re-unwrapped to the specific size you want to use so as to control the orientation across the pixels to be the best it can be.
It’s a complex subject matter that bot many developers put time into because of the runtime GIs that make it completely useless.
Baking lights is essentially a “thing of the past” for many modern day games.
Doesnt mean one shouldn’t know and do the process properly at least once…
