Adaptive DMC and different render.

[ARTECONI-CGI]

Hi Zdravko,

I've just sent you the file.
Thx for the support.

Kind Regards,

Giacomo.

[Svetlozar Draganov]

Hello,

Thank you very much for your scene.
We would like to inform you that this is expected behavior when Sub-Pixel Mapping is ON and Brute Force is used.
The generated Indirect Light from Brute Force when Sub-Pixel mapping is ON is always with less intensity than when Sub-Pixel is OFF - and with the increasing of the Image Sampler subdivisions the illumination becomes even less. This is very obvious if Linear Work Flow setup is used and it is not locked to Adaptive DMC Sampler, the same result will be generated from Fixed or Adaptive Subdivision Samplers.

You can avoid such differences in your renders if you either turn off Sub-Pixel Mapping, or by using Light Cache or Irradiance Map engines instead of Brute Force.

[Svetlozar Draganov]

Hi all,
Another problem I have noticed with the dmc is that sometimes raising the max subdivs increase the noise instead of clearing it.
I can't understand why this happen unconsistently.
Giacomo.

This is also expected and it is because when you tell Vray to shoot more Camera Rays , it starts to fire less DMC rays (material / light / dof / motion blur etc).
And it is developed to work this way because otherwise when Image Sampler subdivisions are increased the final render-time won't be acceptable at all.
Since with every Camera Ray at least one DMC ray is fired - when Vray shoots a lot of Camera Rays it doesn't really need to fire all DMC rays specified in material/lights and etc subdivisions.

There are two ways to fix this: we have to either decrease Clr.Threshold value in DMC sampler , or increase material/lights subdivisions.
In most cases both parameters should be tweaked.

[vlado]

Well, V-Ray does print a warning that subpixel mapping may produce incorrect image brightness

Best regards,
Vlado