What causes this shadow acne and how to fix it?

With Nanite and Lumen disabled, there are these shadow artefacts on some objects. The pattern is static in screenspace and stays where it is when the camera is moved.

This looks like traditional shadow acne but not sure.

What causes it?
How can this be fixed?

Hello there @volumetrix!

if you are not using Nanite and Lumen, please make sure the following settings are adjusted in your project settings:

Thank you for the suggestions @brs-sebascova !

  • There is no difference between virtual and normal shadow maps.

  • TSR and TAA do hide the pattern to some extent but it’s still there. Temporal approaches are not something I want to include for other reasons.

  • The normal maps seem to be correct and the effect happens with several different ones.

What is interesting is that the issue does not occur for materials with parallax mapping effects. Otherwise it does happen with several other materials where a point light gets close to a shadow casting surface.

The issue is also solved by baking the lighting and shadows in the scene.

I wonder if there are any settings that would allow for better handling of close proximity point lights?

On further investigation, the issue goes away when the material is replaced with a simple shader material (still using the same normal and diffuse maps). It seems the issue is to do with the material and not shadows/lights.

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