Displaced Volumes and Shadow Maps

[ikarus]

I noticed that if a volume has a displacement shader and the scene lights use shadow maps, it appears the maps are generated, then the volume is displaced, which ends up causing the shadow map to be displaced, instead of recalculated, causing strange illumination effects

the attached image shows a sphere volume with a displacement shader with a spotlight + shadow map generation

the top left area of the volume is where its most obvious, as all the volume there isnt self shadowed (no scattering no over-blown lights)

would there be a way to get mantra to render the shadow maps after displacement or is the only way to get proper shadows this way using raytrace shadows (which take obscenely long to render) ?

[LaidlawFX]

you got a hip file? to Play with.

Displacement should run first before the surface, and then the light, shadow, etc.

[ikarus]

you got a hip file? to Play with.

Displacement should run first before the surface, and then the light, shadow, etc.

Attached.

Attempting raytraced shadows hints at what I want, as it renders with a volume step size of 0.1, but to get the detail I want, I need a much higher volume step size (ideally 0.01), but raytraced shadows through a volume at 0.01 step size...doesn't happen.

noisevolume_fields.hip

[LaidlawFX]

Attached.

Attempting raytraced shadows hints at what I want, as it renders with a volume step size of 0.1, but to get the detail I want, I need a much higher volume step size (ideally 0.01), but raytraced shadows through a volume at 0.01 step size...doesn't happen.

you should e-mail support, and see what they have to say

The only thing I can add is to see if you're happy with the speed drop/image change with turning your Shadow Volume Quality to .5, on the other hand you could potentially try a system with more shape derived from the volume and less from the shader, the pyro shader is relatively a black box. I got 1:41 on the render(with SVG @ .5), so that's not too bad for production. Maybe just render it bigger than shrink it down. It may be a cheaper alternative, than decreasing the volume step size.