noise

[cdavis]

im getting alot of niose in my render here. I have high samples & looking through my passes it seems to be in the lighting & gi passes.

my settings are adaptive DMC min 3 max 100
my subDiv multiplier is 80
my HDr is high res & seems fine
any ideas ?

[vlado]

What are your color mapping settings? Also, what is the noise threshold of the AA and the DMC sampler?

Best regards,
Vlado

[cdavis]

color mapping settings are
linear multiplier
dark&bright multiplier @1
gamma 2.2
subpixelmapping n
Dont affect colors: On

the DMC samples are left at default

ailasing filter is Area @ 1.5
clamp out put : 3
affect swatches : On

[MHolmstrom]

Sub-pixel mapping may contribute to noise.
Also, you might want to use a low-res copy of the HDR for lighting and hi-res for reflections/refractions only. There's usually no point in averaging huge HDRs for diffuse lighting.
Are you using Brute force GI for primaries?
If you're using a dome light for the HDR lighting, you could try increasing it's subdivs.

[cdavis]

i did make a low res HDR & blur it slightly & have it effect diffuse only & it was still there. i am using brute force as primary & light cache as secondary.
if you turn sub pixel mapping off though isnt that when you get blown out pixels?

[MHolmstrom]

Well, since you're clamping the colors to 3.0 instead of 1.0, sub-pixel mapping won't necessarily help with aliasing artifacts in the first place.

[cdavis]

ok. ill put it to one too. but what im noticing in the matte shadow pass is where the object is casting shadow on itself it seems smooth lighting, but everywhere else seems niosy, not sure if that means anything!

[MHolmstrom]

Difficult to say without seeing, but some render passes (rawreflection) may well have lots of noise even if the beauty pass is smooth.
You could take a look at VRayReflection and VrayLighting -elements to determine if the noise is caused by insufficient glossy reflection samples or area light samples, respectively.

If you're about to start a crusade against noisy renders, I'd strongly recommend to read Demystifying V-Ray DMC Sampler.

[cdavis]

cool. thanks for the pointers.
never really noticed it before , we render lots of cars & only this one I started to see it. but my settings are what i usually use.

but ill have a read of that link, thanks again

[Yannick]

Hi Chris,
have you try with Irradiance Map as your primary and brute force as secondary GI.
The noise looks like the brute force needs more samples.

[cdavis]

yeah, the gi pass is silky smooth, the niose seems to come from shadows . IR map just takes too long. but having read that link below, & putting in some settings I never would have, it's eliminated the noise altogether.

[Komposer]

What is the noise threshold of the AA and the DMC sampler?
default is 0.01
but u need 0.007 or 0.005 or so...

is "Lock treshold to DMC sampler treshold" on?
for me - better is "off"

[RobPhoboS]

What is the noise threshold of the AA and the DMC sampler?
default is 0.01
but u need 0.007 or 0.005 or so...

I've had to use 0.002 or 0.001 in a couple of renders but obviously your render time will increase by a significant amount !
Of course if you are rendering a still you can remove some noise in post, then re-sharpen IF you wish but it can take time getting it nicely right.

[RobPhoboS]

If you're about to start a crusade against noisy renders, I'd strongly recommend to read Demystifying V-Ray DMC Sampler.

Cheers for that link, I wish I saw it 2 weeks ago, heh, well hopefully lots of good info in there, certainly looks like it !