Stochastic Opactiy causes empty squares

[Robert]

I create a falloff shader on the opacity channel for an X-Ray rendering and when rendering with the stochastic method I get empty squares in all channels. Not sure if that's a limitation or not, but the old method works excellent.

[vladimir.nedev]

I can't reproduce this on a simple test.
Can you attach an example file ?

Greetings,
Vladimir Nedev

[Robert]

Send you an email.

[vladimir.nedev]

Thanks for the scene.
I don't think this is something that's fixable however.

The issue is that the adaptive image sampler cannot detect any noise in those buckets and so it does only 1 sample per pixel in them.
The only way to fix it is to increase the "min subdivs" to at least 2.

The "stochastic" mode makes things worse, because it adds additional noise.
Even in the "normal" opacity mode you can see the issue - some of the lines are not complete.

From my tests, it seems much faster to use the "normal" opacity mode in this case.
I guess this is because most of the image is transparent objects with many levels of transparency, with otherwise simple shaders.
The "stochastic" mode creates a lot of additional noise and if you want to clean it,
you would have to raise the max subdivs as well, which is much slower in the end.

Greetings,
Vladimir Nedev