Splotchy shadows on basic walls HELP! UE5

Hey all, having an issue with basic lumen lighting. It seems there are these bumpy shadows on regular walls. Any ideas? Thanks.

This is a known issue for lumen, especially indoor lightning. You are getting patches, I also get fully jagged shadows.

Try to use baked lighting for indoors. For now, use lumen for outside scenes.

Hopefully, it will be fixed when UE5 comes out.

For interiors it can also depend on how you construct things, you need to split up the walls into separate pieces

I have exactly the same issue, walls, ceilings and everything is its separate mesh.
The distance fields look OK, the lumen scene debugging is not helpful and I get these splotchy areas in places that are far away from the light source.

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Enabling hardware RT may be of use to you, if the option is available. More generally, there are two things that may help:

  1. Crank up Lumen’s final gather quality. This generally reduces splotchiness at a cost to performance, but it is a very reliable quality lever.

  2. Assuming that white plane is an emissive object and not a rect light, then your scene quality makes sense: lumen struggles with small emissive lighting, because they’re inherently harder to trace against. If you go into the object’s properties and tag ‘emissive light source’, it will tell lumen to avoid culling it, and I believe shoot more rays as well, so it may help alleviate some quality problems, just some thoughts.

As a general rule though, avoid lighting your scene using only emissives, unless they are very big (at least twice as long and wide as yours), and dimmer. Big and dim lights are much easier for lumen to trace against without quality problems. Alternatively, you can combine a dim, small emissive light with an actual light source, which generally achieves good results at the cost of some extra setup time.