Lightbleeding problems

I am gathering experience in lighting my scenes.
It is getting better, but not good yet.

My current problem is, that I do not understand, why I have so much light bleeding in my scene.
The room is made solely of the pillars and plates. There are four plates between each pillar and the roof is a scaled plate.

I gave the lightmap of the plates much attention, it has a resolution of 128*128.
I am very happy, that there is no bleeding between the plates. But on the top and the bottom of the room, it is still very ugly.

Settings Lightmass:
Static lighting level scale: 0.2
Indirect lighting quality: 4
AO is on

Settings lightsource:
Shadow bias 0
Contact shadow length length: 0.25

I hope, some of you are having a suggestion, what I am doing wrong.


PS: Just replaced the roof (which was one scaled plate) by many plates without any scaling.
That makes it better, but still not good.

Check the actual lightmap density in the viewport by hitting ALT-0. Green is good, blue is too low, red is too high. I suspect the roof still has a very low lightmap density and that’s causing your issues, compounded by the UV layout in your screenshot which has a lot of wasted space and doesn’t seem to have the UV islands at a consistent scale.

Your lightmap resolution is 128, so you have 128x128 texture to store all the shadows for the mesh. If you look at the part labeled “front” it will have only like 16x16 pixels for storing shadows. If the part is like 16x16 meters large it means you only have 1 square pixel per square meter! So, if there is a part of this meter which is hanging outside in bright light and a part which is inside in the shadows the lightmass will put some average value on it -> bleeding.

I would end the ceiling exactly where the wall begins, so there is no overlap.

Yes, first the issue is that the resolution is too low, for a large surface you need to increase it. The other issue is that you should avoid having things like the floor/wall/ceiling overlapping, this causes shadow from one side to bleed onto the visible areas, or lighting from one side to bleed as well.

Got it :slight_smile:

Thank you Interference, scha and darthviper107, you rock.

I thought, overlapping was a good thing for generating shadows. Now, that I have understood lightmaps, it is very clear.
Thanks for the hint with the viewmodes, that helped with an additional problem.

Best regards