Very strange lightleak issue with outer walls

Hello all, I have one very strange lightleak, I now which object causes it but I can’t find a solution.

All my objects have good working custom made lightmaps, no overlaps, no leaks, every UV is aligned to the grid with the 1/lightmap res. formula, more then 4 pixels gap between islands and everything builds fast.

When I add my outer walls (one object) it causes leaks on objects that worked before. This room is the worse, it has leaks all over the place.

Can anyone please explain how this is possible? Am stuck since 2 weeks right now, feeling a bit meh atm :confused:

I’ve added some screengrabs to clearify things


You could hide some bsp brush inside the wall to block light completely. This is what they’ve done in Xoio Berlin flat scene. Just make it a tiny bit thinner than your actual wall so it’s not visible at all.

Have you built the lighting with production quality?

When you add the exterior walls you get less light inside, which makes leaking & blotchiness problems like that more likely to occur. The way to fix it is to add light sources to the windows, increase lightmass quality in world settings and/or increase the lightmap resolution of the meshes and make sure you build in production quality. Also, if that whole house is split into two meshes only(interior and exterior) i highly suggest splitting it even more if you want to make the best of light baking.

heartlessphil: I have done this but the results were the same
jonimake: yes
jacky: I tried this but I had one problem: The sunlight was blocked by the reflector planes in front of the windows, so I even had less light. I’ve searched for an option to make them invisible to the sun but never found that option. Do you have any idea? That setup with lights and reflectors is already in place but I disactivated it because of this blocking issue. Also, I have split up my exterior walls in 10 blocks, still have to put it all together.

As long as Cast Shadows as Two Sided(or something like that) isn’t enabled in the plane’s properties it should let the sun light pass through. Split the interior as well. Then you can drag and drop every part from content browser and set the location to 0,0,0 while they are all still selected, that way they’ll be placed where they were in your modeling program.

Also, make sure your floors and ceilings don’t extend beyond the walls

Thanks man, the difference is amazing when they don’t extend beyond the walls. I have no more lightleaks atm.