Hello Eiffert,
there is already this great thread we had going
https://my.aximmetry.com/post/4926-aoreflectionsshadows-flickering
where, thanks to you, I have already received a wealth of invaluable information on the topic of "Shadow/Reflection problems in Lumen."
To make the topic understandable for others who are also experiencing such problems, I am creating a new post here to summarize the topic clearly and concisely. It looks like this at the moment, I hope the Filestage link works because it's best to see the reflections in motion. Below are a couple of attached images to show where the reflections are working well and where they aren't:
sometimes we get great reflections and sometimes they are still pretty rough/raw (pixelation effect). Especially when the camera is moving and we have movement on the virtual screen. Lumen reflections seem to have problems with quick changes in contrast. That's where we get the crawling/pixelation effects.
The following settings are from our first thread mentioned above and they have made the reflection crawling a lot milder. It also seems that the reflections are reacting faster, but that's maybe just a conceit:
################################################
For "DefaultEngine.ini" File
[SystemSettings]
; Previous VSM anti-boiling settings (keep them here)
r.Shadow.Virtual.SMRT.RayCountLocal=8
r.Shadow.Virtual.ContactShadowLength=0.05
r.Shadow.Virtual.SMRT.SamplesPerRayLocal=8
r.Shadow.Virtual.SMRT.AdaptiveRayCount=0
; Anti-crawling / shimmering in Lumen reflections
r.Lumen.Reflections.DownsampleFactor=1 ; 0 = full resolution (sharpest, most expensive), 1 = good balance
r.Lumen.Reflections.MaxBounces=4
r.Lumen.Reflections.MaxRayIntensity=3 ; Lowers fireflies/noise (default is often ~100)
r.Lumen.Reflections.ScreenTraces=0
r.Lumen.ScreenProbeGather.ScreenTraces=0
r.TemporalAA.Upsampling=1
r.TemporalAA.FilterSize=1.2
################################################
We still have some wiggle room regarding performance with the workstation (Threadripper/RTX 6000ADA). So we could crank some quality settings up, if they provide the targeted quality improvement in reflections.
Looking forward to what you think!
Best regards
Marc