glossy refl. very noisy in overbright

[nils_p]

Hi,

I noticed that the vrayReflection renderelement appeared very noisy in some spots. After taking a good look at the renders it only appears in overbright areas of the image. These images had clamping on.

Is there a logical explanation for this?

thx in advance,
Nils

[vlado]

What does your RGB element look like in this place?

Best regards,
Vlado

[nils_p]

Hi Vlado,

This is the rgb render. There are spots that are overbright but that was ok for this purpose.

[pjkw]

The sampling is based on the contrast between pixels, if theres no contrast (like here where its pure white) it won't sample more than your min samples. You could "fix" it by upping minsamples but its not a bug.

[nils_p]

Thanks for the explanation

[InTercepto]

I think main problem is the Clamp... you are clamping overbright values and VRay compares those first clamped samples with surrounding pixels ... because they are clamped to 1 it won't add more samples to those pixels. Now, if you were not clamping you would have some floating point values that are higher that 1, like 1.2 for pixel x and 1.6 for pixel y.... and when VRay compares those two pixels it's gonna know that it needs more samples because difference is higher than threshold.
So as Vlado said bump up min samples or turn off clamp.

[nils_p]

Sounds logical. I'll try one unclamped when I get some time for it.

Thanks!