Hi! I’m a Archviz artist migrating from UE4, trying the new wonders of UE5 and Lumen, but I have encountered this problem and have been two days that i’m searching and no one seam to talk about this wich is the weird shadows in the corners when using Lumen
to demonstrate i have this images below:
If you see in the corners of the walls and the encounter of the wall with the ceiling has this weird shadow that should not exist. I’ve tried turning off anbient occlusion, different modeling methods, different lighting, rendering in a bigger resolution… so i dont what to do to fix this.
Can you guys help?
What version of UE5 are you on? I believe some versions of UE5 have an issue where ambient occlusion isn’t applied properly over the scene, which can create strange artifacts.
Lumen’s main GI solver isn’t great with super-fine detail, so they have an AO pass to paint in high-frequency shadowing, which doesn’t always look better than before.
There are some CVARS for adjusting the intensity of that AO or SSAO like effect, but I can’t find them right now. Will reply later if no one else knows them.
My guess is it’s probably something to do with the short range AO feature- there’s a CVAR to disable it, although I don’t remember it off the top of my head. should be under .shortrangeao
Hello,
Any solution? i have the same problem.
And i have used commands like:
r.Lumen.ScreenProbeGather.ShortRangeAO
r.Lumen.ScreenProbeGather.ScreenTraces
It’s not an either On or OFF solution. As far as I remember from my tests you can dial down the intensity from some CVARS, but again I don’t have Unreal installed at the moment so I can’t verify.
My tests were also with Unreal 5.2
EDIT: I found some of my notes:
r.Lumen.ScreenProbeGather.ShortRangeAO.MaxMultibounceAlbedo 0.5 default on cinematic
with 2 - the AO is reduced, with 0.1 the effect is stronger. But the radius seems to be set by the
Hi,
I am trying to fix this and I will try with the values that Sebastian has set. Chatgpt gave me these parameters, i don’t know if are correct but i am putting those to test:
r.ContactShadows 1
r.Lumen.ScreenProbeGather.ScreenTraces 128
r.Lumen.ScreenProbeGather.ShortRangeAO 0.5
r.Shadow.Quality 5
r.Shadow.DistanceScale 1
r.Shadow.MaxResolution 4096
r.Lumen.Reflections.MaxRoughnessToTrace 0.6
r.Lumen.Reflections.HitLighting 1
r.Lumen.GlobalIllumination.Quality 4
r.Lumen.Reflections.Quality 4
r.Lumen.Translucency.Reflections 1
r.Lumen.Reflections.TemporalReprojection 1
r.Lumen.Reflections.MaxRayDistance 10000
r.Lumen.ScreenProbeGather.DownsampleFactor 2
r.HZBOcclusion 1
r.Lumen.Reflections.MaxRadiance 1
r.Lumen.Reflections.ScreenPercentage 100
r.LightPropagationVolume 1
r.Lumen.SceneLightingQuality 4
r.DistanceFieldAO 1
r.VolumetricFog 1
r.VolumetricFog.GridPixelSize 4
I would be very careful about using ChatGPT for UE settings recommendations. Since the data it uses is basically guaranteed to be outdated from the newest engine version, it will never be totally correct. A lot of the settings in that list contradict eachother, represent outdated features, would run extremely badly, or simply don’t exist at all .
I’m comfortable saying that @Sebastian___'s reccomendation of r.Lumen.ScreenProbeGather.ShortRangeAO.MaxMultibounceAlbedo is probably the winning factor here, as when I test out the setting it clears up issues that look very similar to what you’re describing.
I have this problem too. I’ve included a basic example of what I am encountering. I would like to get as close to the look of path traced but using lumen with screen traces off which also gives me the same result as setting r.Lumen.ScreenProbeGather.ShortRangeAO 0. The look of screen traces on is close or close enough but it gives me a weird traveling darkness in seems and corners when I move the camera. The AO like effect from lumen is very un natural. I would really just like to be able to tone it down a few notches. Anybody figure this out yet? I see it in all sorts of renders and it makes me wonder if people just don’t notice or have just accepted it as something you gotta put up with.
If you mean
r.Lumen.ScreenProbeGather.ShortRangeAO.MaxMultibounceAlbedo
r.Lumen.ScreenProbeGather.DownsampleFactor
Yes. They do exactly what I would like to do except it seems like they put it back in Screen Tracing mode which creates this weird traveling darkness effect near the edge of the frame when it intersects seems or corners. The CVARS you suggested reduce the darkness but the effect is still pretty obvious. If I could solve that it would be great so thank you it’s on the right track for sure!
You can just disable screen traces for GI and/or reflections. That might solve your problem, or at least force the shortrangeAO Down the more accurate hardware path?
Hey everybody. To clarify what I am attempting to do. I want to use Lumen and no screen ScreenProbe stuff. The reason why is I always get strange effects from it when I move the camera. It’s almost like a shadow demon is just off camera trying to darken the corners and wall seams.
Today, after playing a bit with things I probably shouldn’t ever touch I ran across this CVAR
So far it has been the most effective thing I have found that allows me to get as close to the path trace look using Lumen instead for indoor scenes. I turn off Screen Traces and ShortAO but that leaves me with very dark corners and wall seams. That CVAR I found allows me to reduce that unnatural darkness. I set it at 0Zero. So far it’s the closest I have been able to get. I don’t know if it is the best option but for now I am getting at least close enough results until a better solution comes along. I still am counting on people with a much greater knowledge of UE and Lumen to be able to provide some more experienced solutions.
Oh Also, I am strictly using this for offline rendering.
This combination seems to give me very positive results with a couple of my basic test scenes. Your mileage may vary. I hope it helps because this issue has bothered me for a bit.
So, the ScreenProbe system is pretty much the core of what lumen is. It’s not talking about tracing the rays in screen-space (that would be screen traces) but the process of actually integrating them into the radiance buffer. The terms are confusing though, but I believe you’re talking about screen traces?
Posting a video would be great, because that definitely sounds like screen traces, it could also be just temporal accumulation artifacts, which you could fix by using the PPV to flush history through lumen faster for better resolve.
I don’t think I’ve ever touched r.Lumen.HardwareRayTracing.MinTraceDistanceToSampleSurfaceCache, and I tried out every single lumen CVar back in the UE5 EA days. HELP says it’s used to stop surface cache texels from hitting themselves and exploding, but that has nothing to do with corner darkening. That is baffling.
I’d definitely try out 5.5’s new hit lighting path if I were you then, it’s giving far better resolve of corners and small details and might fix your problem.
Also, if you’re offline, how come you’re not using the PT?
I have no idea why this bot chose this forum in particular, but unless you’re offering workers comp for injuries sustained during badly-traced rays, this is the wrong place for you.
