Translucency volume flickering issues with VFX.

Development Rendering
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1

Hi,

We’re seeing an issue with VFX that use the translucency volume cascade where VFX that are in shadow are flickering as if they are suddenly in outside in full daylight. This seems to effect all particles that are in the second cascade. We mainly see this in editor although there are reports of seeing it on Windows packaged builds. It seems to be related to sampling from the virtual shadow map and if I comment out the CollectLightForTranslucencyLightingVolumeInjection() block in TranslucentLighting.cpp (line 2570ish) the problem doesn’t occur. Our translucency volume is set up to cover a 215 metre area (15m first cascade, 200m second cascade) and each is 48 voxels wide/high/deep.

I’d usually use PIX to investigate but the issue doesn’t occur if PIX is attached and I’ve been unable to get a RenderDoc capture without it crashing. I’m wondering if anyone else has reported anything like this, or if you have any thoughts as to what might be going on?

Thanks,
Matt.

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i’m assuming you have an interior shot?!? make sure the geometry surrouding it is thick enough and can cast shadows on all, expecially border voxels. you basicly should use walls as thick as the voxel gap. so… it cannot sample and hence leak light from the outside.

alternative is to disable or tone down exterior lighting and use megalights to fake exterior lighting influence.

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That’s a good shout but I think the region surrounding the interior is more than thick enough to prevent light leaking. I can pause the sim so nothing moving and the flickering will still occur.