random black buckets in volume

[racoonart]

Hello,
A colleague of mine created a rocket starting effect consisting of several intersecting volumes. The biggest of those shows random black buckets when rendering (Vray 3.60.04). Other volumes may have the same issue but I haven't seen any so far. I read in the documentation that light cache speedup may yield such artifacts so I decreased the value to 0.1. This however didn't resolve the problem. Not sure which information I could provide to be useful to help me find the problem in this setup.
Please see the video below that shows the flickering buckets. I also attached a screenshot of some of the settings.
https://vimeo.com/269866962/4b9a326835

Any help is much appreciated.

[George Barzinski]

Hi,

there are several steps that could solve this problem:

- Install the latest Phoenix nightly build and try again
- Set Light Cache Speedup to 0.0
- Disable Light Cache option

If the problem remains you can attach the scene to dissect what's causing these artifacts.

P.S. Do you render the scene on multiple machines?

[racoonart]

Yes, we're using around 20 machines to render the sequence so we're rather reluctant to install a new version if not absolutely necessary Is there any specific reason why you are proposing that? Some bug fix in that regard?
We'll try to lower the speedup value. Disabling Light cache will dramatically increase the render time so we regard this only as a very last option.

[Svetlin.Nikolov]

Hey,

Since you didn't mention the Phoenix version you are using and we're fixing stuff all the time (there have been changes to the Phoenix light cache even after 3.10), checking with a latest build is a must. This way we'd know we're not chasing issues that are already fixed.

If you are using DR, you also have to make absolutely sure that you have the exact same installation of Phoenix on all machines and that it installed correctly.

You can make the install process easy by using the command-line installer - https://docs.chaosgroup.com/display/...+and+Uninstall

Cheers!

[racoonart]

Classic rookie error, sorry We're using Phoenix 3.10.00 Build 180212.
We can reproduce the problem reliably on one machine, so it's not network related. LC Speedup factor of 0.0 doesn't make a difference. Disabling LC also doesn't get rid of the problem. Another thing we found out is that it doesn't appear when rendering a smaller region, only when rendering the whole (6k spherical) render. So I assume the sample placement or search radius is somewhat screen-space dependent.
We wanted to try the nightly builds but we're on max 2014 and it seems there are no nightly builds for max 2014 =/

[Edited] the errors occur even without LC enabled.

[racoonart]

Ok, we tried the latest nightly with max 2017 and still get the issue. We prepared a stripped down scene that we can provide if you want to have a look. We just need to get the download link to you privately (not via the forum).
The job's deadline is creeping up so we're understandably a bit worried, especially because there doesn't seem to be a workaround

[Svetlin.Nikolov]

Oh, definitely need to have a look at this is figure it out. Please send the link over to my forum name @chaosgroup.com.

Thank you! Hope we'll have good news soon!

[LarsSonparsson]

Are you using "adaptive lights" in Vray global render settings? I had similar problem earlier and changing it to "full light evaluation" helped.

[racoonart]

@ Svetlin Nikolov: You got mail
@ Lasse Kilpia: That does indeed fix the problem! The buckets have disappeared. Thanks a lot for the hint, much appreciated

[Svetlin.Nikolov]

Ah, yes, thanks for reporting this! Will be looking into this...