Refraction and strange buckets

[akc]

Hello Everybody,

for some reason our refractive objects get strange bright buckets, so it looks like this:



There are just some rect lights in the scene, nothing special, IM+LC as GI. We did not use distributed rendering in this case.

The problem is that we can't reproduce it and it looks different on the same render machine, but most of the time it looks good. This is why we can't send you any render scene for testing...

We switched to Maya 2015 Sp5 Extension Pack 1 with V-Ray 3.0 (official build) in January 2015 and still can't find any solution for that. May be it's related to our old scenes (Maya 2013/V-Ray 2.4) or some thing like that...
Does anybode has the same problem? Is there any solution?

Best regards,
Alex

[waaazoo]

that reminds me of my second problem in this topic

http://forums.chaosgroup.com/showthr...ange-splotches

For now, I couldn't find a solution. Support is looking into it. All my test scenes render fine with Vray2.4 (whatever Maya version) but have bad buckets with Vray3.0, DR + "Use Local Machine". Can you try to uncheck "Use Local Machine". BTW does it appear only when DR rendering ?

[Morbid Angel]

All your machines are running exact same vray version? Also does it look correct with using brute force?

[akc]

Guys, thank you,

in this case it is not a Distributed Rendering related issue, both images were rendered locally. We will try render it with brute force, but it's just a workaround, not a solution, because we actually use IM+LC most of the time.

@waaazoo
We have the same problem with distributed rendering (the second problem of your topic), you are not alone! All of the machines have the same V-Ray version installed. With V-Ray 2.4 it was pretty clear... if one of the render nodes produces bad buckets, then ALL of them are bad. But now with V-Ray 3.0 it is not really related to particular render node, the same render node can produce both good and bad buckets.


Greetings,
Alex

[waaazoo]

Guys, thank you,

in this case it is not a Distributed Rendering related issue, both images were rendered locally. We will try render it with brute force, but it's just a workaround, not a solution, because we actually use IM+LC most of the time.

@waaazoo
We have the same problem with distributed rendering (the second problem of your topic), you are not alone! All of the machines have the same V-Ray version installed. With V-Ray 2.4 it was pretty clear... if one of the render nodes produces bad buckets, then ALL of them are bad. But now with V-Ray 3.0 it is not really related to particular render node, the same render node can produce both good and bad buckets.


Greetings,
Alex

I understand the question of Dmitry. Using Brute force is more to see if it's LC or Irrmap which cause the problem.
You can try to make these tests which were suggested by support:

1- IrrMap (primary) + BF (secondary)
2- LC (primary) + BF (secondary)
3- IrrMap (primary) + none (secondary)
4- LC (primary) + none (secondary)

[akc]

Hello everybody,

unfortunatly it is not caused by GI.

I tested it with default settings (no GI!) the result is still very strange.
Same machine, same scene, the same time but we get different images:



But now we can at least reproduce it and I'll send the test scene direct to chaos group support.

Best regards,
Alex

[Zdravko.Keremidchiev]

The result looks strange. It will be best to send us a scene so we could have a look.

[akc]

Hello Zdravko,

thank you for your reply, i have already send you the scene using my company e-mail (this is why you probably can't track it). The support says that it was fixed in the latest nightly build. Since the problem is very critical, it looks like we have to switch to nightly build everywhere (all our workstations and the render farm). If you have some information about next official release, please let us know.

P.S. Actually we have found a workaround for it. The problem was in Ward brdf reflection type, the artifacts are not there if we use Blinn for example. As soon as the refraction amount is non zero and reflection brdf-type is Ward we get such strange buckets. And I really could not believe my eyes, completely different results using the same scene. Isn't it "deterministic Monte Carlo"?

Best wishes,
Alex

[Zdravko.Keremidchiev]

Yes, we use Deterministic Monte Carlo.
I am glad you found a workaround, I'll keep it in mind in case someone else show up with the same issue.

[vlado]

Isn't it "deterministic Monte Carlo"?

That doesn't mean "bug free"

Best regards,
Vlado

[freedomfries]

I'm glad I found this thread. I'm working on a piece of sheer cloth, it has a bit of thickness, so that refractions may work properly. I can confirm that I was getting artifacts like inconsistent buckets the moment I had any amount of refraction. The BRDF model was Ward(VrayMtl). If I switch to Blinn, the artifacts disappear!!! So it appears I can reproduce the problem too. There is no GI in my lighting, only a light dome and rect light. Maya 2015, Vray 3.00.01. Hope this helps!