Blotch issues on solid matte surfaces Interiors

[Streetwise]

I'm having some issues with a weird, almost morie' pattern on both my flat painted ceiling and flat painted wall. The issue seems to be a GI issue. The ceiling and wall material are a plain diffuse colors, no reflections, 48 subdivs.

HDRI light - 256 subdivs
Reinhard burn .15
Adaptive DMC 1,10 (1,12 didn't make a difference to AA)
IR Min/Max -4,-1
HSph 155
Interp. 20
IR/LC bounces 1, .88
LC Subdivs 1200
Use LC glossy rays is ON.
Prefilter/Retrace Threshold are both OFF.

So I noticed that if I rendered the scene locally with my three nodes, I saw the issue. Changing my HSph from 100 to 150 seemed to have fixed it. BUT, anytime I send the job over to Backburner for the three nodes to do on their own, the issue is still there (see screen shots). I can see that there's going to be a problem as soon as the Prepass happens, and then it's confirmed in the render.

Thanks.

[AlexP]

Try upping your interpolation samples.

[Streetwise]

Try upping your interpolation samples.

I tried Interp. samples of 30 and 40. Doesn't seem to make a difference. Also, the same issues with an override material present. BF at 80, takes care of the issue, but it's quite noisy and VERY slow. Too slow, in fact. Also, I tried turning off GI, but it renders black at least in the test area Not sure where to go from here. I'm starting to think that the HDRI dome light may be an issue?

Edit: but wait! I just tried turning on pre-filter 100, and Retrace threshold at 1 with a fixed filter at .04. Much better, but still there, so I think I'm on to something. Any suggestions?

[alexyork]

Try interpolation up to 60 or 80. I often find 60 to be a good place for large, soft, general GI. You will lose some finer detail in areas but it should help.

[Svetlozar Draganov]

This is very odd - if the image is calculated by multiple machines it is fine but if it is calculated on a single machine is not?
Would it be possible to send us the scene along all external assets for investigation?
Which version/service pack of V-Ray/3DSMax/OS are you using?

[Streetwise]

Yes, if I render locally with three nodes + workstation, it seems to have been fine. But when I sent the job to BB (three nodes only), the issue would show up. I was able to fix it by prefiltering and retracing, so that's good.

I'm still on 2.40.04. So do you still want the file? If so, I'll make sure the problem is still there before I send it over.

3dsMax 2014 SP5, Backburner 2015, Windows 7

[Svetlozar Draganov]

What about if you render on a single machine but without using BB?
When rendering with BB is DR also enabled or each machine calculates separate frame?

[Streetwise]

What about if you render on a single machine but without using BB?
When rendering with BB is DR also enabled or each machine calculates separate frame?

This pertains to a single still (no frames). It does not present an issue on my workstation only. I'll try bypassing BB and send it to a single machine as soon as one becomes available. Might be a day or two yet.

I have Spawner running all three nodes. Only one node has BB Server running. From my workstation, I have DR enabled for the two non-BB nodes. So when I send a job to Network Rendering, it goes to the BB server node, and then branches to the two other Spawner nodes from there. So the final render is handled across all three nodes with 32 buckets working on it. Does that make sense?

[Svetlozar Draganov]

Thanks for the explanation.
So the only difference in the setup is BB right? If you run the job directly via V-Ray DR the issue disappears?

Have you got any errors/warnings during the BB rendering? You can check/send us BB log as well as V-Ray log files for any errors/warnings etc.

Are you able to reproduce the issue on a simple scene with the same setup, or the issue persists only in the original scene?

[Streetwise]

So the only difference in the setup is BB right? If you run the job directly via V-Ray DR the issue disappears?

Have you got any errors/warnings during the BB rendering? You can check/send us BB log as well as V-Ray log files for any errors/warnings etc.

Are you able to reproduce the issue on a simple scene with the same setup, or the issue persists only in the original scene?

Yes, it seems as though running it through BB makes the issue much worse (see screen shots). I haven't figured out how to send the image to the three nodes and exclude the workstation. Maybe that's not possible with 2.40. Otherwise I would test it that way. For now though, BB is the only way I can pass the job off to the three nodes.

One thing I noticed is if I render it with WS only, it does 4 pre-passes with a good final result. If I render it with 3 nodes + WS via DR (no BB), it does 1 pre-pass with good final result. If I render it with 3 nodes only (via BB), it does 1 pre-pass with bad results.

The only warning I get is to turn on LC retracing.

No sure what you mean by simple scene. I removed all of the interior scene contents, props, etc, and the issue is still there. I will PM you with a link to the archive file.

My workaround in all of this was turning on pre-filter to 100, and Retrace threshold at 1 with a fixed filter at Nearest, Interp. samples at 10. That made it look very nice, BUT the render times were horrible. Some of that is that I don't quite what I'm doing!

[Svetlozar Draganov]

It is not possible to exclude the workstation in version 2.x, this is only possible in version 3.x.
Would it be possible to send us stripped down version of the scene for investigation?

Is the issue still there if GI is disabled?

[Streetwise]

Is the issue still there if GI is disabled?

I don't know, because turning GI off causes it to render as black, even with default lights and/or material override. I sent you a PM with a link to the zip file. Thanks!