Noisy diffuse reflection

[seq]

Hi,
we have a problem with a diffuse reflecting metallic board.

Please take a look at this image:

http://upload.sequenz.com/vray/seq101209.jpg

As you can see the metallic board in the middle looks fine at the bottom, but very noisy at the middle/top area, where a diffuse reflection of a window with a Skylight Portal (Subdivs 40) light can be seen. Why is it so noisy there?

Using Maya 2011 SP1 under Win 7 64bit and the NB from 06th december.

Sampler Adaptive DMC with 2/20 and 0.01, IRmap + LC, Adaptive Amount 1.

VRayMtl had a diffuse colour of dark grey, Brdf Type Ward, Reflection colour v=0.76,
Amount=0.76, Reflect Glossiness = 0,871, Subdivs=40, Fresnel on, IOR 16.

Using Sun+Sky as environment.

Any hints?
TIA
Lars

[vlado]

You can try reducing the Noise threshold for the Adaptive DMC sampler; 0.01 may be too high - something like 0.005 or 0.003 may work better.

Best regards,
Vlado

[seq]

Thanks Vlado. How can I forget the threshold!? 0.005 seems to do the trick.

[raymarcher]

Or if possible a reduce noise filter in post production

[seq]

We had tried that, but the results were not satisfying. So we decrease the threshold. Wish we could double our render capacity