Lumen GI and Reflections feedback thread

[Krzysztof.N]

@Captain_Trips

But I was surprised to see the default r.LumenScene.Radiosity.Temporal.MaxFramesAccumulated is 4. It takes way more than 4 frames to accumulate. I also get the same slow update when setting r.LumenScene.Radiosity.Temporal.MaxFramesAccumulated to 1.

Setting it to 1 will result in blending 50% history in shader, so it doesn’t completely disable history:

NewNumFramesAccumulated = min(NumFramesAccumulated + 1, (float)MaxFramesAccumulated);
float Alpha = 1.0f / (1.0f + NumFramesAccumulated);
TexelRadiance = lerp(HistoryRadiosity, TexelRadiance, Alpha);

Outside of temporal, there’s also time slicing (we only update a portion of radiosity atlas each frame). This is controlled by r.LumenScene.Radiosity.UpdateFactor.

BTW the main source of lighting lag is World Space Radiance Cache (r.Lumen.ScreenProbeGather.RadianceCache.* has controls for opaque).