Universal Settings scene.

[Svetlozar Draganov]

Universal settings control the image quality via single parameter - Image Sampler Threshold. Hence controlling the separate properties of the scene is not the main aim of this approach.
In general if something is noisier you have to just decrease Threshold value until you get the noise-levels you are looking after.

However it is still possible to use DMC Sampler and secondary rays subdivisions in order to decrease the amount of noise locally but you have to have in mind that the number of the subdivisions should be much greater (usually x10) comparing non-universal approach due to the fact that by default Vray subdivides secondary rays subdivisions by the max AA subdivs. In Vray 3.x we've introduced an option to disable that internal subdivision called "Divide Shading Subdivs" which will force Vray to use the user input subdivs without subdividing them, so you don't have to bump them to extreme values.

If this option is activated which is by default there will be almost no difference between 8 and 16 glossy subdivisions since they both will be subdivided by 100 - in order to get a desired noise reduction you should use value like 160 or more depending on the rest DMC Sampler settings like Adaptive Amount / Adaptive Threshold / Adaptive Min Samples and Min Shading Rate(in version 3.x).

Another quick approach to increase the quality of the DMC rays globally would be to use Subdivs Multiplier into DMC Sampler Settings.

[bigbossfr]

Vlado, whats about this universal settings :
AA min : 1
AA max : 10
AA Threshold : 0.010
DMC Sampler subdivs mult : 0
Min shading rate : 16

It works great (with BF + LC GI) !

[glorybound]

isn't AA MAX supposed to be 100?

Vlado, whats about this universal settings :
AA min : 1
AA max : 10
AA Threshold : 0.010
DMC Sampler subdivs mult : 0
Min shading rate : 16

It works great (with BF + LC GI) !

[vlado]

isn't AA MAX supposed to be 100?

I chose 100 because it is a high enough value to cover most cases. But in practice many people lower that.

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

Universal settings control the image quality via single parameter - Image Sampler Threshold. Hence controlling the separate properties of the scene is not the main aim of this approach.
In general if something is noisier you have to just decrease Threshold value until you get the noise-levels you are looking after.

However it is still possible to use DMC Sampler and secondary rays subdivisions in order to decrease the amount of noise locally but you have to have in mind that the number of the subdivisions should be much greater (usually x10) comparing non-universal approach due to the fact that by default Vray subdivides secondary rays subdivisions by the max AA subdivs. In Vray 3.x we've introduced an option to disable that internal subdivision called "Divide Shading Subdivs" which will force Vray to use the user input subdivs without subdividing them, so you don't have to bump them to extreme values.

If this option is activated which is by default there will be almost no difference between 8 and 16 glossy subdivisions since they both will be subdivided by 100 - in order to get a desired noise reduction you should use value like 160 or more depending on the rest DMC Sampler settings like Adaptive Amount / Adaptive Threshold / Adaptive Min Samples and Min Shading Rate(in version 3.x).

Another quick approach to increase the quality of the DMC rays globally would be to use Subdivs Multiplier into DMC Sampler Settings.

Humh

Will need to re-check my tests. But I think that when I had noise threshold set to 0.0075 I was getting acceptable Light pass but not reflection pass. Then I went to 0.002 and reflection was better-I think I actually settled on it and light was way over the edge with quality. So I just wondered if I can somehow manually boost per reflection quality.

In any case you are saying that I will need big numbers due to subdivision or not if I were to use the Divide Shading Subdivs. I pretty much have 3 materials in my scene now. So the one causing reflection Issues could be set to 200 to double+ the samples on it and in return it should produce better results without wasting time on light samples via threshold approach.

Will test it. Thanks!

[joconnell]

On a related note I presume that any min shading rate samples are still governed by early termination?

[joconnell]

Humh

Will need to re-check my tests. But I think that when I had noise threshold set to 0.0075 I was getting acceptable Light pass but not reflection pass. Then I went to 0.002 and reflection was better-I think I actually settled on it and light was way over the edge with quality. So I just wondered if I can somehow manually boost per reflection quality.

In any case you are saying that I will need big numbers due to subdivision or not if I were to use the Divide Shading Subdivs. I pretty much have 3 materials in my scene now. So the one causing reflection Issues could be set to 200 to double+ the samples on it and in return it should produce better results without wasting time on light samples via threshold approach.

Will test it. Thanks!

Vlado mentioned trying out an option on the render elements to have them considered more heavily for anti aliasing which might partially solve the issue. I was using raw light passes in maya over the past while which had the "consider for AA" option in them and it definitely helped for lights that would have been either too low or materials that didn't have enough solid diffuse to allow clean light sampling.

[vlado]

On a related note I presume that any min shading rate samples are still governed by early termination?

Yes.

Best regards,
Vlado

[RockinAkin]

If you're going the completely automated route - wouldn't a true Universal approach be setting your AA Max Subdivs to 100, and your Min Shade Rate to 100 as well?
Then all that matters in your scene would be your Image Sampler Color Threshold (controlling your AA samples amount), and DMC Sampler Noise Threshold (controlling your secondary samples amount).

[vlado]

If you're going the completely automated route - wouldn't a true Universal approach be setting your AA Max Subdivs to 100, and your Min Shade Rate to 100 as well?

Will be too slow to be useful.

Best regards,
Vlado

[RockinAkin]

Will be too slow to be useful.

Even if the DMC noise threshold is set high?

I've always suspected that the default noise threshold value of 0.01 almost always makes the DMC sampler use the upper limit of available secondary samples... but I cant tell for sure since there isn't a DMCSampleRate render element yet.

[vlado]

Even if the DMC noise threshold is set high?

Well, you can certainly try and see what happens. But I still think it is not practical.

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

Is Irradiance map subdivision also controlled by Universal settings? I tried to get smooth GI today at 150 subdiv settings. I kinda failed.

[bennyboy]

Is Irradiance map subdivision also controlled by Universal settings? I tried to get smooth GI today at 150 subdiv settings. I kinda failed.

I'd go with BF/LC, scrap irradiance map. The beauty of this method is it's simplicity: all noise gets controlled from one place.

[bennyboy]

If you're going the completely automated route - wouldn't a true Universal approach be setting your AA Max Subdivs to 100, and your Min Shade Rate to 100 as well? Then all that matters in your scene would be your Image Sampler Color Threshold (controlling your AA samples amount), and DMC Sampler Noise Threshold (controlling your secondary samples amount).

That's a pretty interesting thought. Rockin, have you done this?