UE 5.7 – Directional Light Intensity Takes Time to Darken Scene

Development Rendering
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1

Hi everyone,

I’m working in Unreal Engine 5.7 and noticed something odd with Directional Light. When I reduce its intensity from any value down to zero, the scene doesn’t go dark immediately. Instead, it gradually darkens over time.
For context:

  • My Directional Light is currently set to Movable

  • I have a Sky Light in the scene

  • Post Process Volume has default auto-exposure settings

Any advice or step-by-step setup would be greatly appreciated.

Thanks in advance!

2

You can’t do instantaneous lighting transitions with Lumen in any practical way. Best you can do is increase the update speed in the post process volume.

3

Hi Arkiras,

In Lumen Global Illumination, I changed the following parameters:

  • Lumen Scene Lighting Update Speed = 4

  • Final Gather Lighting Update Speed = 4

This made the transitions faster, but they now feel sequential. For example, the sky darkens first, then after a short delay the buildings, and finally the foreground.

Do you have any advice on how to make the entire scene darken more uniformly, all at once?

4

Dim the directional light slowly and fade it out over a couple of seconds instead of just instantly turning it off.

Could also opt to just turn Lumen off

5

I tried everything, but it still isn’t fixed.