vrayvolumegrid/next gpu

[super gnu]

i was just having a random play with vray volumegrid on Next GPU.

empty grid, with volumetric set to smoke density, and a couple of nested noise maps. made a nice blobby block like swiss cheese.

i then (using IPR to see what i was doing) drove a camera through it.



HOWEVER, i notice 2 issues.

1) i get shadows cast by the volume grid on the vrayplane floor disappearing completely every so often. (i actually noticed this when scrubbing the timeline in ipr too, but assumed it would not be present in final render..)

its only ever for a single frame, so doesnt appear to be due to camera intersecting denser areas (my first thought)

im rendering on a single machine so its not a dr issue.



2) camera movement is not smooth. ive got MOblur enabled, but i see no evidence of it, and it seems the volumegrid is moving in discrete "steps" relative to the camera. gives overall jerky appearance which is not present in viewport playback of camera.


ive attached max file (zipped)

as set up, it takes about 2-3 mins a frame on my dual maxwell titan setup.

edit: scrubbing through timeline on gpu IPR, i do get frames with no shadow on vrayplane, however going back to same frame doesnt give a consistent result.. so its a random thing it seems.

[georgi.zhekov]

Hey,

Thanks for the scene. I have reproduced both issues. Will get back to you when we have more info on what is going on.

Cheers,

[georgi.zhekov]

For the first issue with the shadows - this happens because the V-Ray Plane and the bottom of the Volume Grid are overlapping. If you put the V-Ray Plane a bit below the Volume Grid it should render correctly.

For the second issue - the stuttering is a bug indeed and I have logged it in our bug tracker. For the motion blur you just need to increase the duration and it will show up.

Cheers,

[super gnu]

does this mean geometry intersecting with a volumegrid risks not rendering correctly, but only randomly? or just an infinite plane. sounds like a bug! what if i wanted to have a piece of geometry inside a grid (f.e. a rocket taking off.)?

[georgi.zhekov]

Indeed it's a bug we're already aware of - where overlapping walls won't render correctly. So if the side of the Volume grid overlaps with another geometry it might not render correctly. If the object is inside of the grid it should render fine as long as there is no overlap with the sides.

[super gnu]

ok understood.. thats not so problematic then.. thanks for the advice!