ALSurface Noise

[oglu]

Why does the ALSurface Shader take so much longer to converge?
All other shaders are clean in seconds but the ALSurfaces does need much more samples.

Is there any way todo local samples for the ALSurface?

[Muhammed_Hamed]

Yup, it is usually noisier and takes longer to clean .. on both CPU and GPU

[oglu]

I know that is like that for ever.
But it doesnt mean it should stay that way.

[Muhammed_Hamed]

I didn't intend to justify it, I consider this to be an issue
On CPU I don't touch the ALsurface at all, I usually use Random Walk
And SSS overall in Vray GPU is not great.. we need random Walk SSS like Octane, Arnold GPU and Cycles

[vlado]

Why does the ALSurface Shader take so much longer to converge? All other shaders are clean in seconds but the ALSurfaces does need much more samples.

Can you get me a scene for that? There might be things that can be improved.

Best regards,
Vlado

[oglu]

Here it is Vlado.
Thanks for looking into.

Cheers Oglu

[Angus Hume]

I'm having the same issue. Alsurface is very noisy compared to other materials.

[Xntric]

What other materials are you comparing it to?

Comparing a standard shader with Alsurface triple-layer SSS material is not fair.

[oglu]

Doesnt matter from user perspective. I want to clear my image evenly.

[Xntric]

There will always be effects that takes more samples to clear up.

Comparing a triple layer SSS material with a simple reflective basemtl for example is unfair and the SSS is obviously gonna need more samples

[oglu]

Yes agreed, and Vray should be smart enough to give that shader more samples. Local samples arnt anything new.

[Xntric]

Which i believe it already does.
I'm unsure whether SSS is included in the DMC sampler, but the adaptive sampler should dedicate more samples towards the areas that takes longer to clean up

Try to add the VRaySampleRate render element. Maybe it's just a matter of increasing the max samples.