Render quality

alienarea

Hi all,

very simple question:

Does rendering quality 2 at 100 % equal rendering quality 4 at 50 %?

Bonus question:

The ultimate preset in Render Studio set rendering quality to 4. How big is the increase with higher settings?

Thank you

fastbike1

1. No.

2. The increases in time are roughly linear.

The rendering quality setting changes the internal threshold when Iray considers a pixel to be converged. The convergence criteria is basically a stop threshold for when the bulk of the pixels are "converged".

Rendering quality is not the only or necessarily the major setting impacting your render time or render appearance. Regardless of settings, better lighting will always render faster (and better) than poorer lighting.

alienarea

fastbike1 said:

1. No.

2. The increases in time are roughly linear.

The rendering quality setting changes the internal threshold when Iray considers a pixel to be converged. The convergence criteria is basically a stop threshold for when the bulk of the pixels are "converged".

Rendering quality is not the only or necessarily the major setting impacting your render time or render appearance. Regardless of settings, better lighting will always render faster (and better) than poorer lighting.

Thank you.

If I understand correctly, a 100 % render at rendering quality 2 is better quality than a 50 % render at rendering quality 4?

SpottedKitty

Note that in Iray there's really no such thing as a "100%" render — that number isn't a measure of render quality or "completeness", it's a measure of how much (or otherwise) the pixels making up the render are changing from one render iteration to the next. You can make it as close to 100% as you want, but it should never have a value of 100%. A better measure of completeness is "do I think it looks good". Remember you can stop the render at any time, if you think it "looks good" before it actually hits any of the stop limits.

Tobor

bohlien said:

If I understand correctly, a 100 % render at rendering quality 2 is better quality than a 50 % render at rendering quality 4?

This opens up a can of worms because Iray performs additional rendering computations depending on the derived completeness of the render. What SpottedKitty says is true about there never being a 100% completed render, but the closer a render can get to a reported 100% in its progress bar, the more Iray is able to complete all its steps. A reported 10% doesn't mean the render is only 10% done. As a render proceeds additional filters, such as the firefly filter, are applied to the output. These filters may be applied later in the process, so if you yank a render that's only "50% done," not all processes may have been applied by that point.

The Render Quality and Convergence Ratio settings are designed to allow the renderer to "finish," while giving you more control over the computational requirements of the scene. It's better to decrease quality and/or convergence to control the render than to simply stop it earlier. Of course, the visual difference between these two methods may or may not be readily apparent. There are simply far too many variables involved. But Iray is not just about resolving pixels. It's not a true unbiased renderer -- there are still numerous little tricks it does to improve image quality throughout the rendering process, so when possible, adjust its settings so that your renders get as close to the 100% finish line as they can.

Note that here, 100% here does not mean 100% pixel convergence. It's simply the value Iray provides to denote its progress toward completion. All of its internal processes are evaluated to arrive at this percentage.