Does the AI Denoiser speed up Iray Convergence?

Krzysztofa

I tried a simple test, I rendered the same image twice: one with the denoiser on and one without. While the image with the denoiser turned out nicer looking imo (no random bits of noise in the image), it actually took a few seconds longer to render according to the log file. This goes opposite to what I'd read about the denoiser: that it speeds the render up.

That being said, I've noticed that with the denoiser on, the render itself looks nearly complete after much fewer iterations. So my question: does the AI Denoiser speed up the "convergence" metric in Iray? Or is it more of a "it looks like its almost done to me" type thing?

Togire

The denoiser adds some processing to every iteration do remove the noise. So the iteration time is longer and there is no speedup for what concerns an iteration time.

But you can get a given quality with less iterations, this is why it is considered as a faster rendering.

Richard Haseltine

Denoising isn't taken into account when calculating convergence, as far as I know.

Krzysztofa

Thank you both for the answers, I just have a clarifying question: so the render is considered done when convergence reaches 100% correct? So in that case, the de-noiser doesn't speed up how quickly Daz Studio considers the render to be done?

By the way, is there somewhere I can read further about the various Iray options that Daz Studio provides?

Togire

Krzysztofa said:

Thank you both for the answers, I just have a clarifying question: so the render is considered done when convergence reaches 100% correct? So in that case, the de-noiser doesn't speed up how quickly Daz Studio considers the render to be done?

No. Reaching 100% convergence requires an infinite time and is impossible to reach.

For DS, the render is considered as done when you reach either "max samples" (iterations), "max time" or "convergence ratio" is reached.

And for you and the render is considered done when YOU consider the appearance of the render as visually good. It is generally around 80% convergence but may largely vary with the scene, the mood you want in it, the use of a denoiser or not, the resolution, etc.

By the way, is there somewhere I can read further about the various Iray options that Daz Studio provides?

There are many resources online. This is the reference https://raytracing-docs.nvidia.com/iray/manual/index.html but there are simplified guides.

Richard Haseltine

alainmerigot said:

Krzysztofa said:

Thank you both for the answers, I just have a clarifying question: so the render is considered done when convergence reaches 100% correct? So in that case, the de-noiser doesn't speed up how quickly Daz Studio considers the render to be done?

No. Reaching 100% convergence requires an infinite time and is impossible to reach.

For DS, the render is considered as done when you reach either "max samples" (iterations), "max time" or "convergence ratio" is reached.

And for you and the render is considered done when YOU consider the appearance of the render as visually good. It is generally around 80% convergence but may largely vary with the scene, the mood you want in it, the use of a denoiser or not, the resolution, etc.

The percentage on the progress bar is measuring how close the actual convergence ration is the to target value - so by default 100% on the progress bar is 95% convergence ratio.

By the way, is there somewhere I can read further about the various Iray options that Daz Studio provides?

There are many resources online. This is the reference https://raytracing-docs.nvidia.com/iray/manual/index.html but there are simplified guides.

Krzysztofa

Thanks again to both of you for the explanations, this clears up a lot of my misconceptions about Iray.

alainmerigot said:

There are many resources online. This is the reference https://raytracing-docs.nvidia.com/iray/manual/index.html but there are simplified guides.

That Iray reference seems a bit over my head, and the Daz Iray reference on their docs site is empty... However I did locate this manual for 3ds Max https://www.lightworkdesign.com/images/support/3dsMaxDocumentation/index.html beyond the 3ds Max specific stuff, I'm finding it fairly informative so far.