Overlapping Uv's and lightmaps

Hello. I am interested in getting started with selling 3d models in the Unreal store. However, I read that one of the requirements for models is that they cant have overlapping uv’s so lightmaps behave correctly.

Its not too hard to uv map a model with non overlapping uv’s, but some parts of a mesh (like many small details) can take up alot of the uv space and would be best suited overlapping each other. An example is railings on a staircase.

What if the railings was part of a bigger object like a ship and you wanted to keep everything as one texture or material? How would you fit so much on a uv map without overlapping uv’s while keeping the resolution acceptable?

I don’t have any experience with lightmaps or Unreal yet, so all of this is new to me.



The standard UV for a static mesh can have overlapping UVs. It’s specifically the lightmap UV that can’t overlap. That UV is handled on a separate UV channel. Here is some more info about lightmap UV and how they are created/managed:


Ok so are we required to have a UV set that works with lightmaps?

I know that UV sets meant for lightmaps cant have overlapping faces but is every model required to have a UV set for lightmaps in the first place?

Just making sure because I will have to add this to my workflow.

yes, lightmaps are required for meshes.