qmc / LC

[jonnybefree]

hi to all,
i'am rendering an interior-bath at the moment, using IR/LC, wich takes 30 min. per stripe at the moment, LC precalculated 1500, IR -3/0 at solution 1200 / 900. rqmc - standard.
i've switched to qmc / LC, qmc 50: it takes 13h per stripe!!
i havn't so much experience with qmc, so is there something i have to take care to? lower r-qmc, maybe less subdv. on glossy materials......?

best regards
jonas

[ene.xis]

set all ur mat set to 8
and,
increase either the QMC global value, or adjust the values in the QMC sampler to get more control in render times/noise


ex:
adapt qmc 1 - 4

qmc gi 8

adapt amount 0.85 (or less for better GI, but loooonger RT)
noise treshold 0.003 / 0.002
min samples 8 - 10
global subd mult 4 - 6

[joconnell]

Qmc is a brute force method which does per pixel sampling, almost like anti aliasing so it's a lot more accurate than any other method. Because it doesn't cheat in the ways irradiance mapping does you don't get a lot of speed benefits in getting cleaner renders, it's literally a case of turning up the settings until the noise starts dissappearing. It's well worth using the override material function to make everything a flat white or grey material to see what part of your image is causing the grain so you can isolate your samples to only GI or Area shadows or Glossy reflections.

For doing animation (except static scene flythroughs) though it's far better since a little bit of noise / grain looks far nicer than the flickering effects of irmaps so if you were doing a character animation job qmc / lc is your only bet.

[jonnybefree]

thanks for the tips
but ene.xis, when i set the globals in rqmc to something like 6, wouldn't it blur the nice sharpness of qmc away?

[ene.xis]

its a multiplier...so it will increase all ur settings six times....as well as render times..but not in a porportional way....

one thing is for sure...at this time whenever i go back to IM i come back running to QMC....

[jonnybefree]

aah ok
the rendertimes forced me to use IM. till now...
for sure you can get way better result with it.