Hello, I have a problem with mirror reflections using Lumen in UE 5.5.4. I can’t get rid of the splodges/noise in the reflections.
What I tried so far:
Would be very thankful if someone could help me.
Best regards
Gerrit
Lumen reflections will always reflect the lumen debug view, you can see that under the lumen options under lit in the viewport. The more indirect lighting is in your scene, the more noise there will be. You can try cranking up some of the lumen settings, but working in that view mode will be the best way to see the impact on your scene.
So at the moment I have no chance to get clear reflections in an environment with mostly indirect lighting?
How is it done in the amusement park demo from nvidia? I tried to reproduce the reflection quality with the nvrtx branch but without success so far.
Lumen Reflection View:
These screenshots don’t look like they have any GI/indirect lighting at all, this just looks like direct lighting with raytraced reflections
Should have used a spotlight honestly… can’t tell what I’m looking at here.
Regardless, it’s not really important. It’s the nvidia branch and it says it’s using RTXDI so I assume it is not using Lumen’s surface cache for indirect lighting. The surface cache is what you are seeing in the original post.
If you don’t care about the lighting being less responsive then you can increase the r.LumenScene.Radiosity.Temporal.MaxFramesAccumulated setting to something like 30 and it should improve the result. But it will be slower to update when the lighting changes.
Hi! Check this answer: Flickering in a mirror UE 5.5 - #13 by looore91
These console commands worked great (5.4, 5.6 tested).
I would also like to add a few notes about the Movie Render Queue. Besides adding the same console variables to MRQ, I set “Render Warm Up Frames” (Anti-aliasing) to “True” аnd set “Render Warm Up Count” “Engine Warm Up Count” to 1024. It took a while to render, but the noise almost completely disappeared in the reflection of the mirror.
How are you setting up Lumen? Is it hardware ray-traced? Have you enabled Hit Lighting for Reflections?
Thanks for the replies!
@growl_ey
I tried it with these settings and indeed, the reflections are better. The most impact has the “max refraction bounces” setting which was set to 0. Setting this to 4 like suggested gives a more clean reflection (not perfect yet), but the interior becomes all black now. There is no light passing through my windows now. Enabling skylight leaking brings back some light, but has a artificial look.
@comlys
Yes, it is hardware-raytraced and set up with hit lighting for reflections
