# Weird shadow artifacts with Lumen

**URL:** <https://forums.unrealengine.com/t/weird-shadow-artifacts-with-lumen/1964415>\
**Category:** Rendering\
**Tags:** unreal-engine, question\
**Created:** [August 6, 2024, 3:21pm UTC](https://forums.unrealengine.com/t/weird-shadow-artifacts-with-lumen/1964415 "2024-08-06T15:21:54Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![3dRaven](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/3draven/32/906552_2.png) [@3dRaven](https://forums.unrealengine.com/u/3dRaven)\
**Post date:** [August 6, 2024, 3:48pm UTC](https://forums.unrealengine.com/t/weird-shadow-artifacts-with-lumen/1964415/2 "2024-08-06T15:48:37Z")

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Lumen unfortunately works with accumulated lighting info with extra information from screen space. When you turn the corner the scene changes are so dramatic that it takes a while for the samples to update.

You can try changing the lumen update speed via a post processing volume:

> [@Lumen rendering latency / refresh rate in real time ??](https://forums.unrealengine.com/t/lumen-rendering-latency-refresh-rate-in-real-time/1203410/3):
>
> Lumen Lighting Update Speed Lumen uses a number of caches to achieve real-time performance. While local lighting changes propagate quickly, global lighting changes, like disabling the Sun, can take multiple seconds to propagate. Projects can use the Lumen Scene Lighting Update Speed and Final Gather Lighting Update Speed [controls in the Post Process Volume](https://docs.unrealengine.com/5.0/en-US/lumen-global-illumination-and-reflections-in-unreal-engine#postprocesssettings) to work around this delay at the cost of increased GPU cost.

If there aren’t any dynamic lighting changes in the back rooms then maybe baked lighting would be an alternative.

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