After days of testing I’ve narrowed down the cause of shadow flicker in Deferred renders to HWRT.
ie to fix I simply use r.Lumen.HardwareRayTracing 0
I’m using Anti Aliasing -None with 29 Spatial and 1 Temporal samples.
Since I’m rendering out Object ID passes
Is this a known bug?
Hoping for a fix since obviously Hardware Ray Tracing has lots of quality advantages.
What does the flicker look like?
Hi @comlys
Thanks for the reply!!
After much testing, searching the forums, asking I have returned .
Obviously I want to keep HardwareRayTracing enabled.
So if I were to describe it looks like Unreal is accessing AO data and applying to random frames only in the render, in both Deferred and PathTraced renders.
Its almost as if someone is flipping a light switch on and off on just certain parts of the meshes on random frames.
More obvious in mesh areas with finer detail. I’m rendering City Sample geos.
In another post(I lost the link) you suggested disable all screen traces.
These 2 CVARs seem to help a great deal.
r.Lumen.ScreenProbeGather.ScreenTraces 0
r.Lumen.Reflections.ScreenTraces 0
But the issue still persists. Just not as often.
I am using 29 Spatial and just 1 Temporal samples AA=None as this is for a VFX workflow and am including ObjectIDs in multilayer EXRs as output.
If I switch to Temporal samples instead (1 Spatial, 29 Temporal) the flicker issue is much much worse!
I am also playing with these 2 which seem interdependent
r.Lumen.ScreenProbeGather.Temporal.MaxFramesAccumulated
r.LumenScene.Radiosity.Temporal.MaxFramesAccumulated
Any other suggestions greatly appreciated! I’ve been trying to solve for a couple weeks now.
I’m on 5.6
Do you have a video or something? The only difference between Temporal and Spatial is that it will tick the engine forward. It almost sounds like a driver issue.