Scene with Motionblur not rendering properly

[ben_hamburg]

Hi there,

I´m having trouble rendering a scene with Motion blur.
I was just doing a testrender via backburner and after a couple of frames the scene wouldn´t finish rendering anymore and just got stuck at the end (before "writing output" was done) and would just stay there indefinitely.
The scene has a couple of xref scenes in it , some with matte objects, rendered at 720*405p with BF/LC.
I also used ticked "use embree" and "use embree for motion blur".
I´m gonna start testing what might be causing this problem, but maybe you have encountered it before and help point me to the right direction.
The scene is fairly complex with lots of xrefs and point cached animation and huge textures, so stripping it down for support isn´t really and option...

[ben_hamburg]

Did some more testing and neither disabling "use embree" nor "use embree for motion blur" nor GI helped.
Only after completely disabling motion blur (in the render settings tab and in the vray camera) frames would finish rendering.
I don´t have time to do more testing right now, so I´ll probably have to try to do motion Blur in post.
I noticed that one workstation didn´t render at all due to some PNG-Error, so I could still try to save out another file format. Other than that I have no other ideas, might be a network issue or some xref scenes having problems, but I don´t get how the job renders fine for a couple of frames and then just gets stuck...
Once I disabled motion blur in the camera tab of the render settings, it finished a couple of frames it couldn´t finish before, but after some more frames, it got stuck again.

So...if you have any other ideas....

[joconnell]

Network or local render?

[ben_hamburg]

network...

[joconnell]

Possibly best to open up the scene locally and track what your memory is doing and see if the error log gives you any hints of where it's stopping at for those frames? Is there anything really quick moving or displacement that might overload your memory in that frame? Could you try something like using a smaller bucket size for that frame if it's a memory thing?

[ben_hamburg]

I´ll try to squeeze in some more time for test rendering, I just don´t get how it coul dbe a memory problem, since the rendering only gets stuck AFTER finishing the frame...

[Morbid Angel]

does it actually finish rendering the frame? and just cannot write the output? or does it fail to render at certain area? Can you reproduce this on the problem frame in 3ds max UI?

it could be an exception (error) during rendering, it could be some issue with the deformation of your geometry at subframe.

[ben_hamburg]

It finishes the frame, but then gets stuck on writing output.
For now I´ll stick to Motion Blur in Post, Pixel Motion blur in After Effects does a pretty decent job...
If it´s not a known bug and nobody else has had that issue, it´s probably either a specific networking issue or something in my scene setup. Thanks for chiming in though!

[svetlozar.draganov]

Would it be possible to send us the scene for investigation with instructions how to replicate the issue into our environment?
What is the Vray version that you are using?

[ben_hamburg]

We´re on Vray Build 3.00.04.
The scene has too many assets (proxies, cache files, bitmaps, xrefs) and since I don´t know what is causing this issue, I don´t know what to strip and what to leave in the scene...

For now I´m fine with doing motion blur in post, should I find the time or need to investigate further, I´ll let you know, thanks!

[svetlozar.draganov]

You can send us the full scene also - we will narrow it down.
Here are some general tips how to troubleshoot the scene.

1.(Render Settings)Reset Vray Settings by switching Production Renderer to a Scanline and then back to Vray > test render
2.(Materials) Assign a default VrayMtl as a override material in Global Switches > test render
3.(Xrefs) Turn Off all Xref scenes and objects > test render
4.(Lights) Open LightLister and turn off all existing lights then create one VrayDome or VraySun light > test render
5.(Cameras) Create a new VrayPhysicalCam and run another test render.
6.(Displacement/Hair and Fur) Disable Displacement from GlobalSwitches and hide any Hair&Fur primitives>test render
7.(Plugins) Remove all third party plugins used in the scene > test render
8.(Caches) Remove all animated objects which use external cache files > render

Let us know if after some of the steps above the issue disappears.