I am currently lighting some strand based hair in 5.8. I am using raytraced shadows, voxelization and screen space GI. The issue I am encountering is I need to use “deep shadows” on my lights to get decent shadowing on the hair, but when I do, it ruins the nice soft area shadows from the hair (casting onto the ground/ bg) that the raytracing gives me and adds on top a sharp shadow that does not respect the size of the light source. This occurs when I try deep shadows on spot or directional lights, as you scale the source radius, the raytraced shadows properly blur, but the deep shadow remains crisp.
Is there any setting or cvar that will cause the deep shadows/ deep opacity maps to respect the size of the light source/ cast area shadows? Alternatively, is there a simple way to turn off the deep shadows just on the ground/ background but not overall, so the hair can still self shadow? I would even accept a distance cutoff for the deep shadows, so they dont reach the floor/ bg and end only self shadow the hair.
I have tried raising the resolution and min.resolution of the deep shadow maps. It does look better as you would expect, but it doesn’t fix the underlying issue, as they are still sharp shadows ignoring the light radius. No other deep shadow cvar seems to have an effect on this that I have found yet.
To reproduce my issue, just put a strand hair groom over a floor plane, put a spot light down on it and turn deep shadows on that light and give the light a non zero source width. As the light source expands in size, you get proper area shadows, but the deep shadow itself will remain crisp.