Dynamic Directional Light Artefacts

Development Rendering
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1

There appears to be some shadow artefacts when using a dynamic directional light.

The steps I took to reproduce the issue were:

  • In a new project create a level and add some flat geometry
  • Add a directional light and set movement mode to dynamic.
  • Set the light to a low angle near the horizon.

The shadows cast along horizontal surfaces have odd striped shadows.

138397-shadowartefacts.png
138397-shadowartefacts.png813×375 123 KB

With CastShadows set to false the artefacts dissappear.

138398-noshadow.png

I have tried tweaking the lights settings for Shadow Bias/Filter Sharpen and while this improves the issue it does not remove those artefacts.

2
3

There is a dedicated forum thread for this issue.
And a feature request.

Your options in combating this boils down to either increasing shadow bias
(you can input values above slider limit of 1)
or implement some sort of adaptive biasing yourself(these are discussed in the thread above).