Empty render passes but correc t RGB

[thablanch]

I think that there is a memory management problem at render time when the mesh is instanced.
It happened ‘randomly’ on my animation sequences, that the render elements would come out empty when my RBG tif 16bit render is ok.
The scene is quite memory intensive on <pre-render>, the pre render takes something like 2minutes when the render kicks in for only 30sec.

Could it be because there is no more memory to save out the passes.
Is this a known issue?
This happenend on several machines on the renderfarm, so the computer issue is not in our troubleshooting

Thanks

[svetlozar.draganov]

Have you tried to export to a VRIMG file?
With this format V-Ray will write the image directly on the hard drive without storing it in memory like all other file types.

[thablanch]

Did not tried this, as the proposed solution does not meet our pipeline requirements.
Usually, the passes are turning out well, on most other project. This is why I had the question about memory issues?

[svetlozar.draganov]

It would be a good idea to test VRIMG file format even if it is not suitable for your pipeline - it will give important information if the passes are rendered correctly.
How much memory is occupied during the rendering of this project and how much is available on the participating machines?

[thablanch]

We will for sure give the VRIMG a try... (but I'm 99.9% sure that we will not change the pipe...so I still have an issue)
As for memory, I have no official log, but the rendering park has anywhere from 16gb to 48gb.. After checking, some of the 48gb machines issued 'blank' render passes as well...

[svetlozar.draganov]

What V-Ray/3DSMax version/service pack you are using?
Does the issue appear only on that scene?

[Deflaminis]

There was a bug in older versions of max that when you loaded a render elements preset it would sort of corrupt the pathing information. It's older... like 2011ish, but I wonder if it persists for you somehow. If you added the elements through a preset, trying removing them and manually creating new ones. Does it help? I know it sounds odd but I've seen this with .tif and .png. Not sure it was a vray bug, I think it was a max bug because it also happened with MR scenes.

[thablanch]

Svetlozar : We are on 3dsMax 2014 with Vray 3.10.01

Deflaminis: Yes, this was happening a lot a few years ago, and remove and import new preset was the trick to fix it. However, this time, the trick does not work... I do not know if it was Vray or 3dsMax related back then..

Thanks!

[tashko.zashev]

Svetlozar : We are on 3dsMax 2014 with Vray 3.10.01

Deflaminis: Yes, this was happening a lot a few years ago, and remove and import new preset was the trick to fix it. However, this time, the trick does not work... I do not know if it was Vray or 3dsMax related back then..

Thanks!

Thank you for your update.
It will be best if we can run a test render with your scene file in the same way as you did. Maybe we will be able to replicate the issue here and find what is going on.
We need as much details as possible in order to try to replicate the issue here : versions, service packs, render manager, preset files..

Does it happen if you remove most of the geometry and render with very low settings and low resolution ? Would it be possible to run a quick test ?

[thablanch]

I have a specific piece in this scene, that when removed, solves most of the problems. However, this piece is required. It is a geometry + volume select + morpher + turbosmooth of 6 iteration and the thing is animated. When I get the turbosmooth to 3 or 4 iterations, everything comes back ok ( well, at least the problem did not happen again, but I need further testing)
Removing geometry and low settings works fine.
So I guess that testing it on a not full scene is a little useless. I'll dig a little mode on that piece, but the piece affecting the save seems like a strange behavior.

Thanks!

[tashko.zashev]

Thanks for your update.
Then it will be best if you can send us the file, so can do some investigation.
We can provide you with access to FTP if need. Just contact us via our ticket system (support at chaosgroup.com)