Vray fur with light cache and moblur, render extermely slow

[jasonhuang1115]

Render tests have been done on machines locally and on the farm with different specs. Sometimes the render hangs; sometimes it finished with much longer render time than using BF+BF. Maybe it has to do with hardware issues internally, but we can't point our finger to something specifically at the moment.

[vlado]

Does it always hang with the Zumo drive message?

Best regards,
Vlado

[jasonhuang1115]

Does it always hang with the Zumo drive message?

On couple boxes I have tested locally, yes. It appears in Maya output window with VRay Log level set to "all messages". I can't say that for rendering on the farm though.
I thought it has to do with accessing/saving LC files, but I got the same issue when I specify a dedicated file path for saving LC file or disable auto-save completely.

[vlado]

On couple boxes I have tested locally, yes. It appears in Maya output window with VRay Log level set to "all messages". I can't say that for rendering on the farm though.
I thought it has to do with accessing/saving LC files, but I got the same issue when I specify a dedicated file path for saving LC file or disable auto-save completely.

Ok, so what happens if you disable or uninstall that Zumo stuff?

Best regards,
Vlado

[jasonhuang1115]

Ok, so what happens if you disable or uninstall that Zumo stuff?

AFAIK, there is nothing called Zumo in our infrastructure. BTW, I got this looping before Zumo is running thing with BF+BF too and the render finishes normally.

[vlado]

AFAIK, there is nothing called Zumo in our infrastructure.

Then were does it come from? It's not a part of V-Ray for sure...

Best regards,
Vlado

[jasonhuang1115]

We have discussed this internally and couldn't figure out what the Zumo thing is. But the thing is it may have nothing to do with Zumo as I mentioned in my last post that with BF+BF the render finishes normally with the Zumo message.

[vlado]

Ok. I guess I will try to render a few frames over and over and see what happens. Can you tell me what is the hardware you are using (CPUs) so that I can match it as close as possible? Also, which OS do you use?

Best regards,
Vlado

[jasonhuang1115]

It's a Mac tower with two Intel Xeon E5520 (16 threads in total), Windows Vista 64-bit, 32 GB RAM (DML set to 28GB). Maya 2013 and Vray 2.30.1.

[vlado]

Ah. Mac... ok, will see if we can reproduce this here.

Best regards,
Vlado

[Svetlozar Draganov]

Hello jasonhuang1115

We have tested your scene on our MAC machine - but unfortunately we couldn't reproduce the issue you have.
Since our MAC is not very powerfull > i5 processor with 8GB of RAM , we have a very slow rendering with 10 strands per face - so we decreased this value to 5 per face.
With these settings - rendertime per frame was between 5 and 6 minutes - and we didn't notice anything suspicious during the rendering.

Unfortunately we do not have anything close to your Mac Configuration in our office and if the bug is related to the hardware we won't be able to reproduce it.
Have you got another Mac machine at your environment with different configuration - perhaps single CPU ? If you have please run the same scene on that machine - and compare the results.

If it is possible please try the following tests on E5520 machine.
-decrease fur-count to 5 per face
-use VrayMtl instead of VrayHairMtl
-activate "Use reTrace Threshold" in Light Cache Parameters

[jasonhuang1115]

Thanks for doing the test, Svetlozar. I did a quick test with the production scene (animated character with moblur). With a fairly low Image Sampler setting, the render hangs more than 15 minutes for the Light Cache phase. As soon as the Light Cache phase reaches like 93%, it took a long time to reach 97% and I couldn't wait any longer. I switch the hair material with a Vray material, the whole render took 8 minutes to finish.

If I render a fur ball scene, the scene renders normally with Light Cache and moblur. Interestingly, BF+BF is faster than BF+LC (retrace ON and LC for glossy rays ON). I thought using LC would save render time, but so far it's not the case.

One thing to note is that the production scene has multiple animated meshes for the hero character where only one mesh is visible to the camera. All other meshes for Vray fur and hair material assignment are hidden when rendering.

[Svetlozar Draganov]

Hello again,

It turned out that we had a dual xeon Mac tower into the office - and finally I managed to reproduce the issue , with the last stable Vray build.
I haven't waited to complete the render - after one hour the render was at 3-4% , and the Light Cache has been calculated for much longer time.
A good news is that this bug doesn't exist in the last Nightly Builds - so if you have access to the Nightly Builds please log in and download one of the last ones - if you haven't got please write to support@chaosgroup.com

Thank you very much for your patience and feedback.
Please let us know about the results of your tests with the Nightly Build version.

[jasonhuang1115]

Thanks for confirming that, Svetlozar. Not sure if we will implement nightly build at the moment, but always good to know it's been addressed.

[RockinAkin]

I'm running into this issue as well -

Light cache is taking forever to calculate, getting stuck around the 93%-98%.
When I switch to pure brute-force, the scene renders fine... or if I get rid of the VRayHairMtl3 it works fine as well.

Can I get access to the nightly builds please?