QMC vs Adaptive Subdivision AA

[Frances]

Hi everyone,

I'm having trouble with grain in my renders. I'm using Irrad. map and Light Cache.

Here is a render with QMC at default settings:


For this one, the only difference is that I used Adaptive Subdivision (0/2) for AA:


Thanks for any help.

[percydaman]

when using adaptive qmc, the default qmc settings dont cut the mustard. try .7 and .002 and itll prolly look better.

[Frances]

Thanks Percy. Do I need to change the Adaptive QMC settings? Right now, the subdivision settings are 1/4 (default).

[jow]

im by no means an expert,but try upping the subs on the vraylight (if your using them). also lower the noise in the QMC sampler and up the global subs and the min samples.

cheers.

[percydaman]

theres a thread I started awhile back that has some useful information, but no just keep the adaptive qmc settings at default. The other suggestions are valid as well, but I would leave your light subdivisions at what they currently are and then bump them up if its still looks noise. If your using a high enough resolution irrad map, consider checking "store with irradiance map" on your vray lights then bump up the subdivisions to say "30" and see how that looks.

[flipside]

theres a thread I started awhile back that has some useful information, but no just keep the adaptive qmc settings at default. The other suggestions are valid as well, but I would leave your light subdivisions at what they currently are and then bump them up if its still looks noise. If your using a high enough resolution irrad map, consider checking "store with irradiance map" on your vray lights then bump up the subdivisions to say "30" and see how that looks.

the store with ir map option will make that light a GI light, to be calculated by the ir map, it will disable the raytraced area shadows. So the subdivs on the light have no effect anymore.

If you use qmc AA, you should use higher subdivs for glossies, area shadows, etc... than when using adapt subdiv AA. For example the default 8 subdivs for a vraylight is really not enough, even with high QMC sampler settings. I always use adapt QMC AA and never use lower subdivs value than 16.

I usually set qmc sampler to 0.002 for noise threshold and the rest by default.

Note that changing qmc sampler settings also affect IR map calculation!!

[percydaman]

it will disable the raytraced area shadows. So the subdivs on the light have no effect anymore.

wow didn't know that...learn something new everyday...

[RErender]

I don't think that is completely true, subdivs still have some effect. I have witnessed artifacts being cleaned up by increasing them.