Trouble with white color bleeding in UE5 Lumen


Whenever I try to render an image in my scene I get these strange white spots on the wall, ground and ceiling.

Does any one know how to get rid of this?

Thanks in advance!

As far, as i know, this can be caused by either the walls being to thin, or by to complex mesh shapes. There was a video, where they break down lumen, and there was mentioned, that Lumen requires simple meshes/shapes, and usually architects built their outer walls in complex shapes → all the outside walls are one single complex mesh, instead broke up in several simple segments.

Take a look at this clip here, at 01:36:20, where they are in that house and switch to the LumenScene View, and most of the interior is black. Maybe your problem is related to this:

Thank you for the explanation! This might indeed be the problem. In UE4 with screen space I used to connect all the walls together to prevend strange artifacts. But if I understand you correctly I need to breakup the walls in to simple shapes/meshes for use with Lumen.

Yeah, thats how i understand it too. Also, you should check, if all of your walls are thick enough, because Lumen seems to be unable to properly recognize planes or very thin walls.
Take a look at this thread too, especially the 7. posting there.

And maybe you find some useful info in the documentation too:

Thanks again for the reply!
For my walls I use real life measurments for wall thickness.
What I also noticed is that when I play around with the Directional Light direction is that the place of light leaking is changing. So this tells us it is indeed a issue with lighting in combination with the walls/ceilling.

See the picture below