[Blender] Lightmap seams on tiling modular pieces

Hi there,

I’ve been trying to get a modular mesh set ready for fiddling around in UE4. I’ve been creating the mesh in blender and am exporting using the FBX plugin. As far as I know, I have done everything necessary to correctly import the mesh into unreal engine.

  • My mesh has two UVMaps
  • First one holds texture coordinates
  • Second one holds lightmap information
  • UVMaps of second layer are not overlapping
  • Islands have 2-4 pixels in padding

Now for some weird reason, once I tile my modular pieces together, I am still getting seams from the lightmap between the set pieces, destroying any form of immersion. I have attached a few screenshots showing you my setup, hopefully one of you can help me out.

That’s normal, each object gets lighting rendered on a separate thread and the indirect lighting can have some slight variations to it, you can try to improve the result in the global lightmass settings by lowering the smoothing value and increasing the quality value. Though that will increase build times. It’s best to avoid situations where a flat surface is split between meshes.
Also, your UV mapping could be better, you don’t need to split it at every angle

So, in other words there is no solid way of connecting two modular set pieces with flat surfaces in UE4? That’s … unpleasent?

Oh, absolutely. I am a horrible 3D artist and my UV unwrapping is probably my biggest flaw. I was on the impression that you had to separate any faces divided by an angle change?

That’s definitely not true.

As for your lightmaps, this helped me a lot:

goodluck :slight_smile:

Thanks for your help. I redesigned my lightmap, only separating surfaces divided by an angle of 90 degrees or more. It already looks a little bit cleaner. Turned up the quality and turned down the smoothing. It got way better. You can still see seams on the ceiling and depending on the lighting a little on the walls, but it’s way better now.

Yeah, as far as UV mapping, if it’s hard edge shaped, you can split on certain hard edges but try to keep as many surfaces connected together as possible. Like for instance with a cube you can keep all of the faces together in a T shape, which allows it to save space and the edges that are connected will give better lighting results.

As for the seams, if nothing works, you might have to combine the separate pieces, it’s not very many polygons so the amount of memory it wastes isn’t a problem.