Time Dependent Noise Issue

[aweidenhammer]

I'm not sure if this is a problem or not, but it's kind of unexpected to me:

Rendering a car animation with a large HDR, if that matters...

We are getting static noise patterns that the car "swims" through. This, I thought was related to the "Time Dependent" setting. We turned on the setting, so that new noise patterns are used for every frame, but the static noise still showed.

After some testing, it seems that using subPixel Mapping with Clamp output set to 1 was the cause. If I set clamp output to off, then the noise patterns disappear. If I turn clamp to On, and subpixel mapping off, the noise also disappears. So I'm guessing that subpixel mapping is doing a random sampling of some sort that is not tied to the timeDependent setting? Just wondering. Not a huge problem, just trying to understand whats up.

Andrew

[olivervfx]

subpixel also can give the incorrect light information..

(can crush lights)

I keep it off.

O.

[vlado]

After some testing, it seems that using subPixel Mapping with Clamp output set to 1 was the cause. If I set clamp output to off, then the noise patterns disappear. If I turn clamp to On, and subpixel mapping off, the noise also disappears. So I'm guessing that subpixel mapping is doing a random sampling of some sort that is not tied to the timeDependent setting? Just wondering. Not a huge problem, just trying to understand whats up.

Which V-Ray version is this?

Best regards,
Vlado

[aweidenhammer]

This is the original release. We still use it mostly in production, and have a smaller pool of nightly build machines that we use when we know if a fixed issue.

[aweidenhammer]

subpixel also can give the incorrect light information..

(can crush lights)

I keep it off.

O.

Yup, I would agree with you, but one of the lighters uses it often, and his shot got approved, so we are kind of stuck with it, unless we want to redev some lighting to account for blasted highlights. Again, this isn't a big deal issue, just one that surprised me... that subpixel mapping would introduce noise.

[vlado]

This is the original release. We still use it mostly in production, and have a smaller pool of nightly build machines that we use when we know if a fixed issue.

Ok, can you try out a few frames with a nightly build?

Best regards,
Vlado

[aweidenhammer]

I tried, and got the same noise.
clamp set to 1
subpixel mapping on

2 frames show heavy static noise

The build was from April26th - 1.90.03

[vlado]

Ok then; would it be possible to get a scene for this? In the code, I don't see right away a reason why it should behave this way, so I need to reproduce it here.

Best regards,
Vlado

[olivervfx]

Try not using subpixel,

curious if it works.

[aweidenhammer]

Vlado, I sent a link to the scene files to the MayaSupport email, since I don't have yours directly. Hope you get a hold of it and let me know whats going on. @Olivervfx, I think I mentioned above, but perhaps not clear... yes, turning off subpixel fixes the noise issue. I'm wondering why subpixel introduces the noise issue to begin with.

[MoonDoggie]

vlado@chaosgroup.com (He posts it everywhere )