LightMap Bleeding in Dark Areas - Modular Pieces

I have created a test scene of a small room using the walls that comes with the starter content and a single direction light, skylight and LightMass Importance Volume. There appears to be a huge shadow bleeding across the corners of the room. I also tried increasing the lightmap resolution but the problem still exists.

Please let me know what I am doing wrong.

Thank you,

Here the screenshot

Try putting something behind the wall to block it, you shouldn’t need to do that but for some reason you’ll get bleeding even if the edges meet correctly and there’s no way for lighting to bleed.

Bleeding Issue

What should I put behind the wall, another wall? Is this a bug in the engine? It used to happen with the model I created also but I thought its a problem with my models light maps that why I created scene with UE4 assets and issue still exists.

Thank you

If there’s no surface that’s exposed to the light, like the inside walls then there’s no reason that lighting from the outside should bleed onto the inside. If you have bad lightmap UV’s then you would get black bleeding rather than white. I think it’s just a problem with how lightmass works, if there’s a corner that isn’t welded together then it can bleed lighting. The only solution I’ve found is to make sure there’s something on the other side to stop the light from bleeding in.

I can’t put a wall behind every time as I am creating a house for Architecture Visualization and it will look odd. Maybe I need to create wall that are welded together to minimize it as much as possible.
Anyways thanks for the help.

When you import a mesh, it splits the mesh to create smoothing groups so even if you have the corners welded it will separate them so that they don’t smooth together. I haven’t tested it but I’ve been wondering if using tangents/binormals will fix that so that it doesn’t have to split up a mesh for smoothing