Lumen reflections have had a performance increase in 5.4 by 1ms in a test scenario at 1440p on a desktop 3060!
I’m talking legit 1ms, not .2 under or over. That 1ms is pretty awesome, but TSR also become more expensive by 1ms(again no .2 under or over) which canceled out any performance gain Lumen got but I don’t even like TSR so it’s not a problem for me.
Btw, this is the first time UE5.4 compiled so I’ll update this post regarding anymore issues(hoping to see Lumen remains stable in motion without TAA etc)
EDIT: Feedback:
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A Cvar that would really help things out would to limit reconstruction from Bilateral and Reconstruction samples from affecting lower roughness like 0.0, 0.01. Reconstruction is needed and more beneficial at 0.05-0.4. When close to 0.0 or 0.01,
ruin what temporal accumulation already does a good job for. -
Lumen Reflections do not jitter in a way where 0.0 reflections can be constructed to the main internal resolution as frames pass on low roughness, if they were, we could get high res reflections in around 5 frames. I guess this was unfortunately handed off to TSR.
To see what I mean, Mirror reflections with (r.Lumen.Reflections.DownsampleFactor 2 + r.Lumen.Reflections.ScreenSpaceReconstruction 0) looks the same as: (r.Lumen.Reflections.DownsampleFactor 1 +r.Lumen.Reflections.ScreenSpaceReconstruction 1)
r.Lumen.Reflections.Temporal.MaxRayDirections 32 is really great at 1/4 res reflections the only thing missing is standalone temporal reconstruction on 0.0-0.05.
5.3 r.Lumen.Reflections.ScreenSpaceReconstruction 0 takes off 5.55555556 of reflection cost vs 22.3214286% in 5.4. In 5.3 Downsample factor 4 takes off 48.71% vs 50% in 5.4
EDIT: The following images have no reflections enabled. In 5.4 Lumen Probe Gather doesn’t give as much specular compared to 5.3(in 5.3, Lumen reflections appear pink in the same area on the blue cube thing with just probe gather) but, this does make it more like pathtracing
