Vray is dropping buckets while rendering an animation....

[Sarford]

I'm rendering some rays to be comped in a shot and I see Vray is dropping buckets when rendering the animation.
The scene is very simple, a spotlight with an animated texture, an V-Ray enviromental fog and an Alembic animated mesh. Not sure what is going on, it doesn't do it on all frames, and the droped buckets are always around the edge of the frame (though not always on the left side). I've had this several times now.

[vladimir.nedev]

Is this motion blur in the images ?
If so, you can try increasing the Min Subdivs in the Image Sampler. Something like 2 should do it, maybe 3.
If not, can you attach or send me the scene ?



Greetings,
Vladimir Nedev

[Sarford]

Hey Vladimir,

Thanks for your reply. I've deleted the alembic from the scene and rerendered the scene again, and the interesting thing is that it will drop the same buckets at the same frames. Even when I copy the stuff to a new scene and make a test render it will have those dropped buckets at the exact same place.
The minimum shading rate is set to 1 because I needed those renders fast and noisyness was not important for now, but when I set the minimum shading rate to 6 it will render all buckets (at least in my super quick one frame test). Anyhow, I've send the file to you email adress.

Cheers, Simon

[vladimir.nedev]

The black buckets are the result of the combination of min shading rate set to 1 and min subdivs set to 1 as well.
With this shading rate, the individual image samples are very inaccurate.
In the corners, where the fog is quite dark, all samples are probably close to black.
So V-Ray thinks there is no noise there and doesn't take any additional image samples.

So, like I mentioned, you can increase min subdivs to 2 to avoid this.
This is how such problems are fixed when there are fast moving objects with motion blur.

In your case, it is better to leave the min shading rate at 6, because the noise is coming from shading the environment fog.
You can then reduce render times by decreasing the max subdivs instead.

Try rendering with min shading rate at 6, and max subdivs at 6 (down from 15), min subdivs left to 1.
When I did that, the scene rendered almost twice as fast with roughly the same amount of noise, compared to the values that were setup.

Greetings,
Vladimir Nedev

[Sarford]

Great info Vladimir, there is still much I have to learn regaring V-Ray!
Eagerly waiting for the tutorials of Richard Yot.

Thanks for the super quick help!!

[EDELVIZ_ARCH]

Hi Sarford,

I have had similar problems in the beginning with Distributed Render. I realize this is not the problem you had, but just wanted to post it here, if someone else who has a similar bucket problem is looking here.
For me it went away after a few nightlies. Also make sure that, if you use DR, all Serves have the same nightlies version installed.

Cheers,
Jonathan