Image sampler vs DMC

[hardrock_ram]

Hi,
I have never quite understood the changes in newer versions of Vray were local material subDivs are disabled in favour of global DMC.

1. Even if I set the global DMC noise threshold really low (0.001), I still get more noise than I get if I increase the local subDivs, with all other things being equal. I thought the whole point of removing local subDivs was that you just set a global noise threshold, and let Vray figure out how many samples needed to reach this?

2. I can mitigate this problem in AA (bucket image sampler) by increasing max subDivs and decreasing the noise threshold. However, I was under the impression that relying on AA is more inefficient and gives less accurate results than having the DMC do more of the work in the first place?

3. Is it correct that by increasing max subDivs in AA (bucket image sampler), you decrease samples in DMC and Brute Force GI since those samples are divided by AA max subDivs? And if that is the case, doesn`t this just decrease the workload for DMC and BF, and instead tax the AA even more?

4. Have I fundamentally misunderstood how AA and DMC work together?

[vlado]

Use #2 and don't worry about anything else; it will be fine - it's efficient enough for the majority of scenes. You can increase the shading rate a bit if the scene has large flat areas or more difficult lighting, but there are diminishing returns on that after a certain point.

Best regards,
Vlado

[mdcvis]

I'm not sure i entirely understand however it sounds like you're trying to get all your samples out of your AA (first bounce)?? Are you not adjusting the min shading rate settings to get more samples into your secondary bounces? That's where you will clear up noise in things like GI and glossy reflections etc with the extra min bounces

This is a little outdated with the latest vray however Vlado did this video on the basics of how it now works; https://www.youtube.com/watch?v=tKaKvWqTFlw

Sorry if that's not what you're getting at though.

[hardrock_ram]

I will see how it goes by working with the min shading rate and doing it like Vlado said

It wasn`t a specific problem I asked aout. It was more about how AA and DMC works together. I understood it reasonably well before they changed it in Vray 3.2 or something ... I have been slow to change over to the new workflow