Heyo, I’ve had this problem for a while using UE5-main too, enabling RayTracing in any Project, even blank ones with no other settings leads to some weird flickering of the light. Turning “Cast Shadows” off fixes the problem but I need my shadows
This only happens in any UE version above 5.0.3… in 5.0.3 everything works just fine.
Changing Shadowmaps or Lighting Method didn’t fix the issue.
What I’ve noticed is that Emissive Materials are excluded from this as well as Point- Directional- and Spotlights with a Source Radius of 0,0 work as intended… changing the Source Radius above 0,0 makes them flicker again. RectLights flicker anyways.
I’ve tried using different GPU drivers but to no avail.
Maybe someone has the same Problem or might know what’s going on ?
I’m having this same issue when I migrated my project from 5.0.3 to 5.1. The problem is in the raytraced shadows because if you turn it off it goes away. I wish they would fix this because I’m stuck.
Unfortunately no , still stuck with the same Problem. Honestly I’m kinda hoping for a possible hotfix, but until then no Raytracing for me.
If I happen to find a solution that actually works without disabling anything really important I will let y’all know
Problem seems to be related to hardware raytraced shadows. The solution… or rather the workaround for me was to change the r.Shadow.Denoiser.* values if I wanted to use the hardware acceleration for shadows.
// enable or disable the denoiser entirely, default 2 for me (can’t see difference between 1 and 2)
r.Shadow.Denoiser
.
// Try value around 4-16, increase until flicker goes away (costly)
r.Shadow.Denoiser.PreConvolution
.
// enable or disable the temporal function, I kept it on
r.Shadow.Denoiser.TemporalAccumulation
.
// Lowering this reduced the flicker in my case (read below)
r.Shadow.Denoiser.MaxBatchSize 1
.
// When Translucency is set to Raster in PostProcessVolume (default) it gives best result
r.Shadow.Denoiser.HistoryConvolutionSamples 1
Rest of the values under r.Shadow.Denoiser.* was a bit finicky in my case with Radeon 6800
In the PostProcessVolume I set the GI for lumens final gather [Global illumination → Lumen Global lllumination → Final Gather Quality ] to 6 (costly) and as above mentioned kept the translucency [Rendering Features → Translucency] to raster.
There might be other settings that I have also done in the project settings but I do not know which ones actually has an affect on it (for the better or worse) for when using the lumen hardware raytracing shadow… aside from activating it of course [Engine → Rendering → Hardware Ray Tracing → Ray Traced Shadows]
The denoiser seem to have a great cost and is very finicky with this card (or in general) so you might want to disable it entirely or tweak it proper.
I ended up disabling the denoiser entirely because of the high cost and it still had some very few flickers.
Using current devbranch as of 2022 12 29 (the “5.2”)
I think the hardware acceleration (at least for AMD cards?) needs some love from the Epic dev team.
Okay the Denoiser does actually seem to be the main problem, I’ve tried your approach and it did fix my shadows, actually the only thing I had to do was just disable the Denoiser. Easy workaround to get your Ray Traced shadows back.
Now obviously depending on your lights there will be noise in the shadows, though at least in my scenes it was barely noticable.
Hello, I have the same problem here, managed to find temp workaround: If in UE5.1 you will switch from SM6 to SM5, turn off virtual shadow maps (switch to another type) and turn on Raytraced shadows - issue will be gone.
, still stuck with the same Problem. Honestly I’m kinda hoping for a possible hotfix, but until then no Raytracing for me.