Render times suddenly tripled

[dhilton]

Hi, hoping someone has some insight into what might be happening. We have a very large scene, Thousands of Vray proxy buildings and props etc scattered throughout. Everything has been rendering fine up till now averaging about 28-45 minutes per frame depending on network render machine.
We tried to render last night after some very minor changes to the scene and render times have suddenly tripled or quadrupled over the network, Vray seems to be spending a lot of time loading image maps, tracing extra rays that weren't there before:

Broken render:

[2014/Sep/16|00:52:09] V-Ray: Number of raycasts: 3816751438
[2014/Sep/16|00:52:09] V-Ray: Camera rays: 339927073
[2014/Sep/16|00:52:09] V-Ray: Shadow rays: 379054157
[2014/Sep/16|00:52:09] V-Ray: GI rays: 0
[2014/Sep/16|00:52:09] V-Ray: Reflection rays: 5341
[2014/Sep/16|00:52:09] V-Ray: Refraction rays: 0
[2014/Sep/16|00:52:09] V-Ray: Unshaded rays: 3097764867
[2014/Sep/16|00:52:10] V-Ray: Number of intersectable primitives: 2725854
[2014/Sep/16|00:52:10] V-Ray: SD triangles: 2375719
[2014/Sep/16|00:52:10] V-Ray: MB triangles: 0
[2014/Sep/16|00:52:10] V-Ray: Static primitives: 350134
[2014/Sep/16|00:52:10] V-Ray: Moving primitives: 0
[2014/Sep/16|00:52:10] V-Ray: Infinite primitives: 1


Good render:

[2014/Sep/13|23:21:15] V-Ray: Number of raycasts: 167326368
[2014/Sep/13|23:21:15] V-Ray: Camera rays: 37545085
[2014/Sep/13|23:21:15] V-Ray: Shadow rays: 42894073
[2014/Sep/13|23:21:15] V-Ray: GI rays: 0
[2014/Sep/13|23:21:15] V-Ray: Reflection rays: 306
[2014/Sep/13|23:21:15] V-Ray: Refraction rays: 0
[2014/Sep/13|23:21:15] V-Ray: Unshaded rays: 86886904
[2014/Sep/13|23:21:16] V-Ray: Number of intersectable primitives: 2567463
[2014/Sep/13|23:21:16] V-Ray: SD triangles: 2373739
[2014/Sep/13|23:21:16] V-Ray: MB triangles: 0
[2014/Sep/13|23:21:16] V-Ray: Static primitives: 193723
[2014/Sep/13|23:21:16] V-Ray: Moving primitives: 0
[2014/Sep/13|23:21:16] V-Ray: Infinite primitives: 1

We have tried eliminating every possibility, even rolled back to the 'good' version but nothing seems to change the render times except for completely turning off raytracing and maps. We even tried assigning just one shader to every object without raytracing and the scene still crawled along. The biggest addition from the good to the broken was the addition of a glass material to some of the building windows.

These renders run fine locally btw, -they are slow but they render without a problem on a dual CPU 24gig machine.

any help would be really appreciated! (we are rendering in version 2.4 Maya btw)

-Darin

[ivaylo.ivanov]

339M vs 37M camera rays. You have increased the resolution probably.

[dhilton]

Resolution is still the same: 2048x1152 and geometry actually got less with some optimization. The biggest change was the addition of a glass material, however this scene wont render even with a single material applied to every object and reflection/refraction turned off. Our only conclusion so far is that the scene file is now corrupt, we have tried removing references one by one and even rebuilding the shot from scratch but still using the base scene which now contains two days of work but the only scene that works is the older scene from the weekend. Until we can get to the bottom of what is happening we are rolling back to that. I was just hoping that someone else had run into issues rendering large amounts of proxies over a network and would have some insights.

[svetlozar.draganov]

Is there a possibility to send us the good and the bad scenes for investigation?
Since the issue occurred just after the glass-material was added have you tried to remove that material and associated objects with it?
What render manager are you using? Have you tried to open the scene on one of the network machines and start the render locally?
Have you tried to reset V-Ray render settings?
Try to disable Global Option one by one starting from Displacement and Viewport Subdivisions if the issue still persist continue to disable the other options gradually.

[dhilton]

Hi Svetlozar,

Let me confirm that we can send you those files. We have tried to remove the glass shader and even tried to render the proxies with a pink basic vray shader and no reflection/refraction. Render server is in-house proprietary and has been used for several years but mainly with Mentalray/Renderman. Have tried resetting render settings without luck. Have not tried rendering on network slave locally yet. We have not tried a methodical troubleshooting of global options but there are no displacements or subdivided geo in this scene. Unfortunately it takes a long time just to start the render so troubleshooting can easily eat through a day and we have a deadline looming. I will contact you directly once I establish that its ok with our production team to send these files, thanks for reaching out.

-Darin

[svetlozar.draganov]

Thank you very much for the feedback.

We understand that the troubleshooting could take hours or even days sometimes but it is the best way so far to find out the root of the issue.

We are looking forward to hearing from you.

[ivaylo.ivanov]

If the resolution is the same, maybe increased image sampler settings? Decreased DMC adaptiveness or threshold? I still think there is a change in the settigns since the camera rays are affected. If you have both scenes, you can try saving/loading preset.