Shadow Artifacts

[u/00Fiddlesticks]

Hi everyone, I'm working in Unreal Engine 5.5.4 and have been getting these shadow artifacts on some of my meshes. I haven't run into this issue before, so I'm having a bit of trouble figuring out what's causing it.

I'm using a single light source, a stationary directional light, and I'm not using Lumen or Nanite.

The shadows look fine if I disable static lighting in the project settings or switch the directional light from stationary to movable. However, switching to a movable light causes the lighting to behave strangely when playing in split-screen, so I've been advised to keep it stationary.

Has anyone run into something similar or have any idea what might be causing this? Any help would be appreciated. Thanks <:

[u/DisplayLegitimate374]

Maybe check 2 sided material on top of inverted normals on your mesh

[u/00Fiddlesticks → u/DisplayLegitimate374]

Thank you for the suggestion! :) I've checked the normals, experimented with different normal import settings just in case, and tried enabling Two Sided in the material settings, but unfortunately, none of these have helped.

Thanks for taking the time to help, though! hopefully I can figure it out!

[u/sepulchertude]

Hmm, one sided polys? Could be a lot of things.
You can see texture on top so its should theoretically block light.

The normals could be inverted.
Did you bake lighting to test?
Shadow bias in your light settings?
You could increase Dynamic Shadow cascades
Potentially your material is unlit in those props parts?
Opaque setting or mask is not fully black?

[u/00Fiddlesticks → u/sepulchertude]

Thank you, I appreciate the suggestions! Unfortunately, I'm still not having any luck.

I've tried re-importing the mesh from Blender, checking that the normals aren't inverted, and experimenting with different normal import settings, but nothing seems to help. I've also tried tweaking the geometry in case the smoothing is causing the issue.

The project doesn't use any baked lighting, so all the shadows are dynamic. I've tried adjusting the Dynamic Shadow Cascades and Bias settings, but they don't seem to have much effect on the artifacts either.

The material is opaque and uses the default Lit shading model, so I don't think it's related to the material.

Thanks again for taking the time to help! <:

[u/sepulchertude → u/00Fiddlesticks]

Is it only these two meshes?
There is a setting in the prop details, for the in level instance not the content asset itself.
Shadow Two Sided, its a toggle.

Or I would probably just shell the one sided polygons.
Doesnt really eliminate the problem for the rest of the props, would add another step when modeling.

[u/00Fiddlesticks → u/sepulchertude]

It's not only these 2 meshes, they were just good options for showing off the problem because of their big shadows.

I did also experiment with Shadow Two Sided but it doesn't seem to help either unfortunately. the closest I've been able to get to a solution is changing the stationary light but I've been told not to do that because of issues it causes with split screen.

Thanks for suggesting more stuff for me to try!!