Subpixel mapping is not working

[Kakashi]

Hi there,

when using Subpixel mapping is ON and Don't affect colors is ON for vray 2.0, Subpixel mapping
is not working.

It is working correctly for vray 1.5.
And if Don't affect colors is OFF, Subpixel mapping is working.

[Zdravko]

We can't reproduce that.
Could you please attach a simple example scene with that issue?

[Kakashi]

perhaps this is not "subpixel mapping" isn't working but Just DMC Sampling may change.
It understands, if "sample rate" pass is checked.

Possibly it is based on that DMC Sampling changed by Vray2.0.

[Kakashi]

This occurs, when Color mapping (Gamma, Dark multiplier,burn etc) is used for DMC sampling balance.
Sorry, I forgot to mention it.

[Zdravko]

Could you please send us a simple example scene to: support@chaosgroup.com
and steps to reproduce the issue?

[Kakashi]

I am sorry to have become late.
I made a easy scene.

Please check a lower image.



sampleingtest_maya2011_vray2.0.zip

[Kakashi]

Would this problem be my misunderstanding not a bug?

[Marti]

Basically, when the Subpixel mapping option is enabled the color correction is applied on a sub-pixel level (during the sampling). In contrast when the option is disabled V-Ray compares more saturated values and there will be more samples taken. For example, if you enable it, V-Ray for Maya will compare sample values that are already affected by the color correction and therefore it will need less samples.
Note that the different colors in the sample render element represent different density of samples.
On the other hand when "Don't affect colors" option is enabled the color mapping will be taken into account for the sampling part but the effect will not be shown in the final render. In another words this option only influences the final image. Whether it is enabled or disabled will not affect the sampling.

[vlado]

Would this problem be my misunderstanding not a bug?

I can't reproduce this issue anymore with the latest builds for the next service pack, so I assume it was a bug that was fixed. Thanks for the scene and the detailed research!

Best regards,
Vlado