UE 5 Early Access issue/glitch with my foliage

Hi all !
I’m new to Unreal Engine and this forum. For a project I need to build a landscape with quite some foliage, trees, grass and so on.
The issue is that when I started to paint my foliage some… “glitches” just appeared, rapidly flashing (See video linked). I don’t really know where to look so that’s why I’m asking here.

Here is the video of the issue : Issue Unreal Engine 5 early access - YouTube

Can someone please help me ?

Hey! Are you using virtual shadow maps? The flickering could be related to that. The strange noise is caused by Lumen GI.

Some console commands you can try:

r.Shadow.Virtual.Clipmap.LastLevel = 22

you can set that to 30 and see if the shadows are getting better.

r.Lumen.ScreenProbeGather.Temporal.DistanceThreshold = 30

try 850 here and see if its better

Hope it helps.

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Thanks for your reply !

I’m sorry I was away a long time and did not see your answer sooner :confused:
I’ll check if I’m using virtual shadow maps and try your solution when I get the time and will keep you posted !

Thanks again !

In case anyone else is wondering, Braitenbug’s comment is indeed the fix for flickering grass and foliage shadows in UE5 with Lumen.

(r.Lumen.ScreenProbeGather.Temporal.DistanceThreshold is the one you need to adjust)


Hi !
Thanks for the confirmation that it works !
I tried myself and indeed it does the trick but isn’t there a permanent solution to this ? I mean everytime I close Unreal the next time I open my project I need to redo the all thing in the console command.

You can build a simple editor widget that writes console commands or you can put them in the .ini.

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Yes, I put it in the .ini to avoid having to do this each time. That will be a permanent fix.