Hello 
While I’m delighted while testing VRay 3.4, I’m facing some misunderstanding about noise threshold: now we have 2 noise thresholds ?! one in the Bucket Image Sampler / Progressive Sampler rollout, and one in the Global DMC rollout. I mean … is the one in Global DMC rollout now obsolete ? I’m a bit confused ! could anyone shed some light on that, please ?
Thanks in advance,
Regards.
As I understand it the one on the Image Sampler pane is the main and absolute noise threshold for everything.
The one in the DMC pane is only for material/shading effects (glossy reflections etc.).
Say you set DMC to 0.5 and IS to 0.01. The material sampling will get terminated very quickly, but the image sampler hasn’t yet reached its 0.01 threshold so it will take over the material sampling until it hits max subdivs or reaches its noise threshold.
THis should result in a very red SampleRate pass (assuming “normal settings”). Now if you change the DMC sampler to 0.005 and leave everything else untouched, there will be more material samples and therefor the actual IS has less work to do resulting in a faster rendering with equal or better quality and your SampleRate pass should be much less red.
Correct me if I’m wrong here but that is how I understand it.
hi Art48, and thanks for your explanations. While these make sense and are conform to the way I used VRay so far, the same naming of the 2 settings now confused me a bit. Previously it was Color Threshold (Image Sampler), and somehow had more sense to my brain … maybe only a matter of habit, but I’d rather ask 
It would be best to forget about the one in the Global DMC rollout; there’s rarely any need to adjust it. The AA noise threshold is the main quality control.
Best regards,
Vlado
True. I always leave it at 0.005. The only thing I change there is the adaptive amount - I set it t0 0.95 and rarely had problems with that but then again the references for that performance increase were pre-3.3. With the new automatic sampling, what sense does the adaptive amount still make?
It will have a measurable effect mostly with the irradiance map or with high shading subdivs.
Best regards,
Vlado
ok, thanks for the precisions !