Unusual behaviour when rendering with Backburner

[Anonymous]

Hello,

The unusual behaviour - unusual for me because it is the first time I am experiencing it - is that from a certain frame, the rendering time increases inexplicably much. E.g. : I have a job that consists of 36 frames. The first six frames render between 8 and 9 minutes, but then the render time increases up to 1 hour and 10 minutes on the final frames. The render farm farm consists of three machines, one of them running both as manager and render server. They have 3ds Max 2016 SP3 and Backburner 2016 2150. The render engine is V-Ray 3.4. There should be no reason of this render time increase because the render is a 360 of an object, and all frames should require about the same time to render.

Any help would be greatly appreciated.

[Alfred.DeFlaminis]

Hello @Anonymous,

I'm not sure this is a backburner problem, this seems like a rendering problem.  You may have to ask about this in Chaosgroup forums.  Depending on how you've lit the scene and setup materials, it's possible for one side of an object to take much longer than others.  This can be especially true if the lights are visible in the render after frame 8-9.  The antialiasing needed to clean up super hot pixels next to regularly lit pixels is quite extensive, and this is a likely culprit for slowing down frames.  The one thing I could suggest is to go to the color mapping rollout in Vray and trying to turn on "Clamp Output' to maybe 2 or so, and see if that helps with your render times.  Without a file I can't offer much more advice, and since it's really a rendering question you may have to ask in the Chaosgroup forums.  

When you render locally (not through backburner) do they take about the same amount of time?  

Please hit the "Accept as Solution" button if my post fully solves your issue or answers your question. This lets me know that I was effective in helping you, and thank you for doing so.

Best Regards,

[Anonymous]

Hello Alfred,

It may not be a Backburner problem, but it isn't either a rendering problem. The lighting is consistent through all of the frames, the camera itself and lights are not animated, only the object rotates 360 degrees. So I have the same camera view and the same position of the lights in all frames. I rendered the same scene using Backburner but not on the three machines (renderBOXX) that make up the render farm, but instead on a couple of workstations from the office. The problem did not persevere in this case, rendering time being more or less the same (22-34 minutes). 

Sincerely,

Tudor

[Alfred.DeFlaminis]

Hello @Anonymous,

Thanks for the update.  Sounds like a problem with the hardware/OS on the BOXX computers, if I am understanding you correctly.  If you net rendered the same shot on 3 other machines and it was fine, then I think we can safely say the original BOXX machines that were slowing down are having a problem, perhaps with memory management, heat, or something along those lines.  I would have your IT department look at them and see what might be causing them to be slower than random workstations around the office.

Best Regards,

[Alfred.DeFlaminis]

Hello @Anonymous,

I just wanted to follow up here, any progress on your issue?

Best Regards,

[Anonymous]

Hi Alfred,

No, no progress. In the Backburner Server window screen, there is a info message regarding 3dsmax adapter, and at the end of the line it says MEM x MB. In our case, that number seems to increase with each frame, e.g. 3870 MB, 4315 MB, 4775 MB etc. Is this a normal behaviour?

[Alfred.DeFlaminis]

Hello @Anonymous,

Those numbers reflect the needed RAM for your scene.  Apparently the ram usage is going up per frame, but without a scene file to investigate it would be hard to tell you why that is happening.  You had mentioned that some random computers around the office were rendering the frames properly, so my assumption here is something is going on with the BOXX machines.   (Heat, drivers, OS problems, .Net, etc.)  

Does the problem persist with other GI methods?  (Or with GI off?)  Is your Settings/System tab in Vray properly configured?  Light cache using more threads than those computers have processors?  You may have more luck posting in the Vray forums at Chaosgroup as this seems directly related to Vray, or send me a private message with a link to the file so I can investigate personally.

Best Regards,

[Alfred.DeFlaminis]

Hello @Anonymous,

I just wanted to follow up here, any progress on your issue?

Best Regards,