# Why does my spot light + volume fog always have something like a Mosaic

**URL:** <https://forums.unrealengine.com/t/why-does-my-spot-light-volume-fog-always-have-something-like-a-mosaic/462754>\
**Category:** Rendering\
**Tags:** light, unreal-engine, Lighting, volumetric-fog, question\
**Created:** [March 23, 2020, 7:01am UTC](https://forums.unrealengine.com/t/why-does-my-spot-light-volume-fog-always-have-something-like-a-mosaic/462754 "2020-03-23T07:01:46Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![Koshari\_Studios](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Koshari\_Studios](https://forums.unrealengine.com/u/Koshari_Studios)\
**Post date:** [January 3, 2025, 2:07pm UTC](https://forums.unrealengine.com/t/why-does-my-spot-light-volume-fog-always-have-something-like-a-mosaic/462754/4 "2025-01-03T14:07:19Z")

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These steps worked for me.

1. make sure to turn on cast volumetric shadows on whatever light you used.
2. Type in the console command exactly this “r.VolumetricFog.GridPixelSize 2”
3. then type in this exactly (warning it is pretty expensive and will use up quite alot of ram) “r.VolumetricFog.GridSizeZ 256” (increse that number if there is still some flicker or jitter.

ALSO, take a look at [this post](https://forums.unrealengine.com/t/volumetric-light-ghost-trail-issue-still-no-fix-for-it/492710/5)

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