QMC question

[skogskalle]

Hi guys!

I read in another post that some of you use QMC settings 0.92 / 0.02 with good results.

This is what I get with those settings... :



sure it renders fast, but its not nearly good enough quality for finals... everything looks really jagged.

other settingts for the scene: GI: IRR-map -3, -1, lightcache 600 subdivs, Qmc samples 8 , Global multiplier 1.0, Adaptive qmc AA 1, 4 catmull rom.

With the default qmc settings the scene renders fine... maybe a bit noisy, but I think thats because of the adaptive qmc aa... with adaptive subdivision aa -1, 2 it looks great with default qmc settings.

What am I doing wrong here? have I simply misunderstood the qmc settings you use? or do you really get good quality pics with these settings?...

any thoughts?

[Morbid Angel]

you did...
when the the numbers of 0.92 / 0.02 were mentioned they ment:
For QMC sampler
adaptive amount 0.92, and noise threshold 0.02

[skogskalle]

thanks for the reply!

yeah well thats exactly how I used the numbers...

heres a pic of my qmc settings and aa for the image above:



could this be a scale issue? I work in centimeters... (1 unit = 1 cm) would this mean I need other settings than someone working in inches?

[Morbid Angel]

hmm i dont know then, since your image looks like its not been antialiased properly. Try qmc sampler adaptive amount 0.8, noise 0.003 and global subdivs to 4.0
also whats your lc settings? i mean sample size

[jujubee]

Settings look fine - what are your IR/LC settings?

[Syclone1]

it almost looks like its just the LC calc with render final image turned off... if it was just a matter of an antialiasing issue then it should be jaggy not noisy??

There is a good posibility that Im way off but thats what it looks like to me.

-dave

[TRGraphics]

The problem is the noise threshold. If you use .02 it will always look like that, even with high antialasing settings. Ok for testing lighting, but nothing else.

[RErender]

should be .002 me thinks

[skogskalle]

thanks for all the replies guys!

Morbid - I know I can change the settings to get better image quality. The problem was that I´d read that you guys got great results with 0.92 / 0.02 settings, and I didnt. Thats why I asked.....

jujubee - nothing special on IRR or LC... I use -3, -1 for IRmap, and 600 subdivs for lightcache, all the other settings are left as default.

syclone1 - nope, its a fully rendered image, not only lightcache calc...

TRGraphics and RErender - aaahaa... ok, if I render with settings 0.92 / 0.002 then it looks great, but takes about 4 times longer. But I thought the default settings of 0.84 / 0.005 was considered too high for the latest beta versions? Isnt 0.92 / 0.002 even higher settings??

I havent used qmc settings to change the quality of my renders before... but it seems to be a great way for making test-renders fast!

[vlado]

The default QMC settings are average. To get better results, you should decrease the Noise threshold to around 0.002.

Best regards,
Vlado

[Morbid Angel]

darnit we overlooked one paramiter, the noise is not 0.02 it has to be 0.002 with 2 zeors after the decimal.

[skogskalle]

thanks Vlado and Morbid!

yup... it seems I just missed a zero in the noise value... 0.002 seems to be the way to go when using adaptive qmc AA, but when using the adaptive subdivision AA I can get clean results with a noise value of 0.005 or even higher...

its a bit clearer now... so thanks alot everybody for helping me out with this!

[davision]

By the way, the problem seems over but I believe the .92 setting you mentioned is LOWER quality than .85 (not higher as you presumed) and should go faster. But yes, knocking down the noise threshold to .002 will slow things down again.

[Morbid Angel]

skogskalle, qmc sampler is not connected to adaptive subdivision AA, instead you have to use its noise threshold located in the same rollout as the adaptive aa settings.

[flipside]

skogskalle, qmc sampler is not connected to adaptive subdivision AA, instead you have to use its noise threshold located in the same rollout as the adaptive aa settings.

It is, if you use higher noise th in qmc sampler, the adaptive subdiv AA will go faster.

Adaptive amount: lower = better = slower

Note that these settings also affect GI and dof and every other QMC related parameter!

When using adaptive qmc AA, you need lower noise th in qmc sampler settings to get a clean AA result than when using adaptive subdiv AA. This may sometimes render longer, but in scenes with glossies and stuff like that, adaptive QMC AA will always be faster.