Realistic Lighting - Can't Avoid Black Edges at Wall Intersections

Hi, I’m currently working an an ArchVis project and I’m trying to achieve the most aesthetic and believable results from the lighting bake. However I keep getting black seams at my wall intersections no matter what I do. What can I do to fix this and avoid this in the future?


My walls are UV mapped and I made sure that the Lightmap resolution is sufficient. SSAO is turned off so all we are seeing is the lightmass bake.


I read that I can align my lightmaps by laying out a UV Grid in 3DSMax and dividing 1 by the wall resolution, then snapping all the vertices to the grid. This is a pain in the *** to do for all the walls and I found that it still doesn’t align quite right. Even if it did snap correctly, what would I do if my wall still has to intersect with a separate mesh? I cannot break my wall into 10 pieces because that would cause uneven shading and break the lighting even more.

Could it be my Lightmass settings? How can I fix this? please help

Thanks for the suggestions. AO is turned off, and I would like to clarify that my walls are all flush and snapped to each other and do not intersect inside each other. They intersect in the sense that they are separate meshes touching each other.

The previous screengrabs were built on High settings Light quality. I have tried production quality and the result was better indirect lighting and smoother lightmaps, but the black edges have remained and even became more prominent on some walls.

Here are my current lightmass settings ( Note: I am using Luoshuang’s Multi Bounce Skylight)

I’ll try increasing the settings even further and see if that fixes it, but I cant help but feel that the problem is with the lightmap UV’s not lining up with the connecting walls/ceilings. Here’s an further example of the way I have my scene set up:

Exterior wall in 1 piece

Same wall on the inside, connecting with the interior wall. You can see the ugly black line where the walls connect. They are 2 separate meshes.

lighmap vis