Using volume grid as a cheaper fog pass - what would cause it to swim / flicker in vray 3.6.04?

[joconnell]

Hi folks!

We're using the vray volume grid with a solid block of smoke (1000 x 1000 x 1000 voxels in the close areas, lower quality further away) loaded in to create a faster version of environment fog for our interiors. We're finding on slow camera moves in detailed environments (think industrial interior with railings and spot lights) that we're getting a bit of slow flicker in the brightness of the fog as if it's opacity is being animated up and down slightly. I've tried with light cache both on and off and i'm running a version with skipthresh set to 0 in case it's a visibility thing - any thoughts?

Cheers!

John

[georgi.zhekov]

Hey,

Can you send over the scene at support@chaosgroup.com so we can check it out?

Thank you,

[joconnell]

It's not sendable in it's current form but I'll replace some models and run the shot to see if we get the same results, if it shows the same error I'll package it up and mail it over!

[stevesideas]

I'd like to know the results. I'm interested in using this method

[Paul Oblomov]

Well, maybe shadow step or smth like that.

[DarrenWallace]

Just thought I'd share how I overcame a similar issue, if not the same. I'm using Vray 5 for Maya but the fix might be the same. I noticed flickering in my volume grid smoke (static VDB for cheap smoke/fog) turning off GI completely didn't help. There is a check box Volume Light Cache in volume grid options, unchecking this instantly fixed my issue. Even though GI was turned off globally the volume grid appeared to still be suffering from the GI flicker with this check box on. Cheers

[^Lele^]

That volume Light Cache is *not* the same as the normal light cache.
You can leave that off (zero influence), and render with standard GI, there should be little flicker.
Also, expect some serious improvements on volume rendering speeds soon.

[joconnell]

I like the sound of that Lele, we're looking at a lot of houdini stuff in the future so this'll be a part of it. Hopefully a bit more volume on gpu stuff also though I'd imagine you'll use up memory if you're using a lot of vdbs!

[^Lele^]

Well, rumor has it the 3090 will come with 24gb of ram.
With a pair of those, i'm sure at least some VDBs would fit. :P

[joconnell]

That's exactly what I'm looking at if my tiny case and 600w psu can take it

[^Lele^]

That's exactly what I'm looking at if my tiny case and 600w psu can take it

[fixeighted]

that's obscene

[joconnell]

Is that an air hockey table?