Depth of Field Noise

[Teriander]

Im rendering a 4K scene in Vray-5, and I have a metal object (drum set) in the background. The depth of field works fine for everything, except the drum set's metal has light-highlight noise and I can't reduce the noise. I've tried increasing the DMC subsamples to very high numbers, but the noise remines. I've also tried increasing the drum set's subdivision, the material reflection subdivision, and played around with the AA. Nothing works.

This only happens when using Depth of Field. Also using a V-Ray camera with "Depth of Field" enabled.

Any suggestions to fix this?

Thanks!

[piotrus3333]

try 500 or 1k max AA samples. also slightly less glossines in mtl will help.
search forum for "noise motion blur". there should be some topics about this issue.

[Teriander]

So you're saying increase the Image Sampler from the default 6 to 500+? This setting here?

Also, is the noise from Depth of Field identical to the noise from motion blur? Or should I search for "noise depth of field".

[sirio76]

No, that’s the minimum shading rates, it may affect DOF but Piotrus was referring to the Max AA samples.

[Joelaff]

What if you render the scene without DOF and then camera map that back on the geometry and render this with DOF??? Doesn't work well with transparency.

[^Lele^]

Im rendering a 4K scene in Vray-5, and I have a metal object (drum set) in the background. The depth of field works fine for everything, except the drum set's metal has light-highlight noise and I can't reduce the noise. I've tried increasing the DMC subsamples to very high numbers, but the noise remines. I've also tried increasing the drum set's subdivision, the material reflection subdivision, and played around with the AA. Nothing works.

This only happens when using Depth of Field. Also using a V-Ray camera with "Depth of Field" enabled.

Any suggestions to fix this?

Thanks!

For now, the pixels giving you issues fall into the category of "high energy, low probability", and can only be cured in one of two ways: brute-forcing the max AA (you should *lower* MSR from 6 to 2, in case, to ensure you give priority to camera rays, which are the ones cleaning this kind of effect), or making the pixels less low-probability/less intense.
If you decide on raising AA max subdivs, do *not* concurrently lower Noise Threshold. The combo of high max AA and low noise threhsold can take exponentially longer to compute.

Otherwise, as Piotr said, if you roughen the shader that will give the engine a better time of it.
You could even be more effective if you paired the roughness with a controlled reflection light (i.e. split lighting for the reflection. Doubled lights, affecting reflections only. The original lights affecting only diffuse.), with just the right amount of brightness to produce the highlights without generating big energies.

TL;DR:
a) Lower MSR to 2, and up max AA to a big number.
b) Roughen the shader, lower the light intensity for reflections.

[Teriander]

I've made several changes that seem to work. I converted to GPU rendering and increased the samples limit from 5000 to 80000. This increased render time, but it helped with getting rid of the noise. My render time was insane, but I just needed a still. So this works. Thanks!!

[^Lele^]

II converted to GPU rendering and increased the samples limit from 5000 to 80000.

GPU indeed uses an MSR of 1, and it cannot be changed.
FYI, the above is analogous to setting MSR to 1 with CPU, and setting max AA to (sqrt 80000 = ~ 282) subdivisions.

Glad you're sorted, whichever way!