Prepass blotches issue

[Streetwise]

I'm having an issue with some DR buckets that are rendering darker than the rest of the scene. It happens during the Prepass process affecting the buckets generated by my local workstation only. The two other render nodes seem fine. If I use a material override, the issue is gone. I tried turning "Convert local file paths to Relative" on/off, with no difference. "Convert to UNC" is off. So I don't think it's a materials issue, but what's weird is that it seems to only be happening to the top portion of the frame?

[Morbid Angel]

I think that's normal so long as your final render looks fine. Does it?

[Streetwise]

No. The render does not look fine in the end. Here's another example where I disabled the single HDRI dome light source and added a V-Ray Sun. Same blotchy problem throughout the image. Out of curiosity, I opened an another older project and tried a re-render and it looks fine. So I really have no idea what to think why this would be happening?

[Morbid Angel]

it could be a missing asset (texture) or something. Have you tried option - transfer missing assets in dr?

[Streetwise]

That's not an option with 2.40 I'm starting the project over to see if I can pinpoint what's going on.

[glorybound]

changing bucket size has solved that issue for me; usually a larger bucket.

[Morne]

I tried turning "Convert local file paths to Relative" on/off, with no difference. "Convert to UNC" is off.

Convert local file paths to Relative should be OFF for most situatiuons. It's a good idea to switch Convert to UNC to ON
Also, open the Maxscript listener and paste this in there:

ATSOps.CheckNetworkPaths = true

This lets you see if your maps are "OK"

Make sure the slaves have UNC access to the same location as your workstation. Run spawner normally. If you're running your spawner as a service, make sure the correct user is running it

[Streetwise]

The script returned "true", so I guess we're good there. Also, I tried switching Convert to UNC to ON, but still no luck. The two slaves are set up identical to the workstation in terms of mapped drives and user name. I started over with a new layout and don't seem to be having any issues. But when I go back and open this old file, same issues. It doesn't seem to matter which various render pre-sets I try from other projects. Same issue. Weird.

[Morbid Angel]

some missing plugin like color correct?

[Svetlozar Draganov]

That's not an option with 2.40 I'm starting the project over to see if I can pinpoint what's going on.

Then try Check for Missing Maps option from the System Rollout - if it is missing map it will inform you in the V-Ray console window and the machine will not join to this job.
This issue could be also caused by different V-Ray version, please double check that all the machines have the same Vray build installed.

You could also try to convert the scene to V-Ray scene, and convert Bitmaps to VrayHDRI via the following tools:

[Streetwise]

All of the V-RAY builds are 2.40.04 so that's not the issue. Also, both workstation and two render nodes are running 2014 SP5, so that's all the same. I also tried using different light methods (HDRI in a dome vs. V-Ray Sun +enviro map) still nothing. The issue happens throughout the seen, even on a vRayMtl with a basic diffuse color. The ONLY thing that fixes the issue is if I use an Override mtl with a basic diffuse color.

Lastly, I tried ticking the "Check of missing files" box in the rollout (see attached), but not sure what I'm really looking at. I get the same report with a different project file that doesn't have any issues!?


BREAKING NEWS....

FROM THE "WHAT THE HECK?" DEPARTMENT:
I just did another render, but this time, systematically deleting the windows. NO MORE ISSUES! With every window I removed, the issue became less and less pronounced until it progressively disappeared. Why would this be?

Before:

After:


Project File:
Example Test File.zip

[Neilg]

did they have a glass material, and what was it?
maybe fog in the glass? different machines may have been reading the scale differently.

[Streetwise]

That's what makes this so frustrating to figure out. The glass is nothing special. Diffuse and Refraction of 255. I even hid the glass layer, same results. I've double checked to make sure there aren't two glass layers that I might have missed... So far, the ONLY way to fix the issue is to hide the windows. You wouldn't think that window frames/grids would be the cause. That's what is so odd. These are imported .skp windows from Google Warehouse. Maybe it has more to do with the limitation of the intensity of light when there's something present in the window openings? I'm going to try different windows in the meantime. Another odd thing I noticed is that the issue is more pronounced towards the top of the frame and fades out by the time the bottom of the frame is reached.

did they have a glass material, and what was it?
maybe fog in the glass? different machines may have been reading the scale differently.

[Streetwise]

Just replaced the windows in the scene with something totally different, leaving the glass IN, and no issues whatsoever. Must be something really flaky with the grid windows that I had selected... No idea. Very strange.

[Morbid Angel]

you want to post a part of your scene with glass....so we can have a look?