ExtraTex passes that use dmc like VrayDirt: how do they tie in with unified sampling?

[joconnell]

Heya Vlado,

Just having a think about unified sampling for passes that aren't tied in to the main render parts. We know that the results of the material / light sampling are fed back into the AA dmc and that decides whether to fire more rays and thus control the quality, but for passes that aren't feeding in to the main loop of DMC, how is their sampling decided? For example I've got a vehicle on a film I'm working on where between 1/10 and 1/12 is fine for AA, and the majority of my light and material samples are fairly high. All fine. Just wondering though when we get to things like a dirt map in an extratex element, if consider for anti aliasing is turned off, then how is the level of sampling decided? As in even if you hit the correct noise threshold for the dirt map on the first aa 1 sampling pass, does it still get brought up through the dmc levels because of the main sampler? Looking at optimizing some render times at the mo so it'd be interesting to find out how these bits get treated!

Cheers,

John

[vlado]

As in even if you hit the correct noise threshold for the dirt map on the first aa 1 sampling pass, does it still get brought up through the dmc levels because of the main sampler?

This is what happens, yes. Which means that in some cases it might be faster to render the dirt pass separately.

Best regards,
Vlado

[joconnell]

Yep - I've got to do a few tests to see which cases are worth doing the separate ones, on a simple test last night on minute long renders, the AO dirt added 10 seconds, but on it's own I got it to 6 seconds - not a massive benefit for setting up a second scene file or render setup but must try it on a slightly more real world scene