Every time I start a new project, I have flickering shadows and problems (blurring) with lighting. You can also notice a strange effect when the texture of sand is present on the material. I have been struggling with this problem for a week now, but I have not found a solution. I think it’s all about Lumen, because when I delete the DefaultEngine.ini file, everything becomes normal.
I can change any settings as I wish, BUT as soon as I do Lumen in ReflectionMethod and Global Illumination, everything gets terrible. I was already starting to think that the problem was not in the Engine itself, because if these lighting bugs appeared when incorrectly configured in the project itself, it would be okay. But, why does this show up at the very beginning of each of my projects? I have already updated Windows and reinstalled the drivers on the graphics card, but nothing helped. Also, in some projects, “shadow marks” were left from the character’s feet. Disabling or enabling Virtual Shadow maps did not help. Disabling Ray Tracing didn’t help.
Commands like
r.Lumen.ScreenProbeGather.ScreenTraces 0
r.Lumen.Reflections.ScreenTraces 0
did not help.
I noticed that if you change the smoothing method (for example, to FXAA), the flickering of shadows stops, but the whole picture seems to be strongly pixelated, and the blur of the mesh (and light) does not disappear. I use UE 5.3
Maybe I’m exporting the meshes from the Blender incorrectly? When importing, I don’t touch anything in the settings
Lumen has a limited number of cards it uses per mesh to cache lighting, and it doesn’t work well when concave areas like this are one mesh. You need to break it up into individual pieces, and you can check the lumen scene debug views under lit to see what’s going on under the hood with Lumen.
The shadows lingering is from VSM, if the character animates outside of their bounds, the cached shadows will not update. You can increase the bounds and the issue will go away.
Thank you! I beat my problem with shadows lingering. But can you explain more about concave areas. I ceparate mesh “by loose parts” in Blender, and it helped a little, but the flickering shadows did not completely disappear. I saw a helpful video “Lumen Explained” from
William Faucher, and tried to enter the commands r.Lumen.Visualize.CardPlacement 1, but nothing happened. Also in Show/Visualize there is no “Lumen scene” or “Lumen Global Illumination”.
Hi, did you manage to solve the problem with flickering shadows? The thing is that I have the same problem, I have it in my posts, the flickering starts just when I don’t use lumen.
I have spent more than 30 hours to solve this problem, but never found a way to remove it, only to hide the problem
Hello, to be honest, I just abandoned the Lumen system, because no matter what I change, the result remains the same. And it’s surprising that no one has encountered the same error (except for those who have flickering lights on the walls or ceilings, which is solved simply by changing the Final Gather parameter). And then, Lumen is more for visualization and rendering, and I will dive into games where this system is still too raw. Do you have a 1650 video card?
I actually spent more than 25 hours searching for a solution to this problem and I can share with you all that I found, some things worked for other people but not for me.
If the previous method didn’t work for you, then try to use the method I described in my post on this site, this method is described in the last post itself
“Problem with flickering shadows in Unreal Engine 5 when using global illumination not in Lumen mode” Rendering topic
