Hello,
Does anyone know how to get rid of these squares in the light beam when using EnvironmentFog Fx?
It is also a lot of grain.
And it’s so slow to render!
Thanks
Up your minimum aa for starters, sometimes if there’s something thin or blurry like heavy motion blur or shallow focus, vray will miss it with the first ray shot into a bucket and assume it’s empty, leading to squares like this!
Thank you, but sorry I could not find the solution.
I always get this empty boxes that move to another place if I change the render area for example.
A bit better if I change to Catmull-Rom image filter
This is mentioned elsewhere and I have had this issue occur also, albeit not with fog but as @joconnell mentioned, motion blur.
If you increase the bucket size this can also help - looks like you have it at 12 or so, and that ‘can’ cause these issues afaik.
Hey, Romain_P,
Thank you for the post. Is there a chance to make a screenshot of your’s Env. Fog setup and share it here? GI setup if you have it, too.
Cheers,
Environment fog *is* slow to render, and noisy: it’s a full-light-transport volume, not a cheap trick (f.e. like the traditional Max ones), and so it takes its time.
Your issues, as mentioned, is due to it being very faint (remember you’re in sRGB space, under a gamma curve) coupled with a low min AA, which makes it miss the detail, and not pass it on to the adaptive algorithm.
So, set min AA subdivs to something higher (2-3-4), and the squares will be filled in.
For the noise, you have one option only, and that is to raise max subdivs, even a lot, to make sure you hit the noise threshold you set (the sampleRate render element will give you clues as to how the sampler is working: red means “raise max AA”).
Of course, you could also denoise the fog element, but that’s beyond the point. 
Now that’s what I call an in-depth explanation Lele! 
Very useful info, thanks.
I’d love to hear about the trick!
Where di you apply the lens blur in? Max? Post?