Why does this particular area light up?

Hi all, I am using lumen, and discovered a small area in my scene with strange behavior. Any object I put in that area produces progressive secondary lighting.
You can see the effect in the video. (I mean the area between the sofa and the table)

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I know this one.

LUMEN is a fantastic software feature.

But it is NOT perfect.

Light will pass through 2D surfaces, even if they are using double-sided materials. The only way I have found to counteract this effect is by surrounding the entire structure with Unlit black cubes:

It works like a charm, but it is a pain in the ■■■ to set up. This cuts off any stray bounce light in the scene.

This is the only solution I’ve found to this problem. I hope there are more solutions somewhere out there, but this eliminated my stray bounce light problem and has served me well.

I used to apply this solution when working with static lighting. And it seems to work again with lumen. My problem was solved.
Thank you very much!


It’s good to hear you were able to solve your problem, I may offer if I can though: do you have access to Lumen’s hardware ray-tracing? It looks like you’re running into problems with SWRT, which makes sense: The Signed Distance Field representation of the scene doesn’t deal well with thin or small geometry, so lumen’s screen traces often are the only way to pick them up, resulting in view-dependant lighting.

Hardware ray-tracing, on the other hand, can deal with meshes of arbitrary dimension and topology, even 2D and one-sided ones. It solves light-leaking and generally results in better behavior, but at a higher base cost.

The cubes trick works great if you only have SWRT to work with, but you can also go into each asset and increase the distance field resolution scale to make it more defined in the lumen scene (warning: this will crank up your VRAM and storage demands, so use judiciously).

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