Stuck Buckets!

[jasonazure]

Hi,

I'm currently having a real problem with the notorious 'stuck buckets' issue. I have a very large scene which contains a huge car model (CAD data from manufacturer) with the 'carpaint' material, including full interior, a number of very hi-poly trees as instanced vray proxies, the same with a number of rocks and quite a large environment ground with displacement and quite a complex blended surface. All seemed fine, until I hit a few frames in a render where the stuck buckets issue occured.

I am using vray sun and sky, with BF + LC GI lighting and motion blur is on.

I have tried simplifying the car paint material as that seems to be the place it most often gets stuck, turning off Embree, reducing the ground displacement subdivisions and reducing the bucket size, but to no avail.

I'm approaching deadline so, I know there's no chance of getting this bug fixed in time, plus I'm not sure I can even send you the data (car manufacturer is very strict about where their models end up), so are there any 'tricks' I can try to get around this issue that I haven't tried already?

Thanks,

Jason

[jasonazure]

After much experimentation I have got the scene to render reliably (so far), but only by switching off motion-blur and the displacement map on the ground texture! Neither being an ideal solution!

The displacement map isn't too bad, as I have bump maps to make it still look 'rough' etc., but losing motion-blur is a real pain. I thought I may get around it by using a velocity channel render and doing it in post, but simply adding that screws the render by either locking up whilst creating the Light-Cache or, if it gets past that point, by getting a 'sticky bucket' that never resolves!

I thought Vray was supposed to be good at handling large scenes!?

[yolov]

It will be hard to figure out what's the cause without having the scene, but that part being already cleared, there's but a few things we can suggest for the moment:
You can try removing from rendering different objects of the scene until the problematic object(s) are isolated, it could be anything.
Do the buckets get stuck at a particular area of the scene each time?
Can you also check if your "geometry generation" for subdivision and displacement is set to pre-tesselated or on-the fly? (setting can be found under "displacement control" and "subdivision" attirbutes on objects/sets)
Can you also try rendering on one-thread for a frame that you know the buckets will get stuck? This might help rule out a potential multi-threading issue. (settings can be found in render settings > settings tab > system > advanced > "max render threads")

[jasonazure]

Hi Yolov,
I've tried removing things from the scene, and I've got it down to basically the car exterior, which makes sense as that is where the buckets normally stick, on the car paintwork or occasionally on the alloy wheels.
I'm not familiar with the 'geometry generation' attribute, can you explain further where I find that?
I'll give the one thread thing a go!
Thanks,
Jason

[yolov]

This is a parameter of the displacement control attributes and the subdivision attributes.
https://docs.chaosgroup.com/display/...rol-Attributes
https://docs.chaosgroup.com/display/...sionAttributes

Those are usually added either on meshes or on the displacement nodes directly (or on groups or sets).