Optimal Iray settings

gibrril_fa945a6cee

Hi all,

I'm trying to figure out the optimal Iray settings for my renders. It would appear that Iray always finishes the render before the max time is reached, yet I still think the result is not as "polished" as it should be.

Attached are two pics: the Iray 01 pic is rendered using the default settings, apart from the max time, which I set to 1500 seconds (25 minutes). Yet Iray finishes the render in about ten minutes. (resolution is about 4000 x 3000 pixels). This still looks grainy to me. (I get about 950 itterations).

The second pic (Iray Samples) is rendered using the same settings and resolution apart from quality and minimum samples, which I increased to double the default values. Now everything seems to be an emissive surface... And Iray still finishes the render in about 12 minutes.

What is the amount of itterations I "production quality" Iray render should have, and how do you get Iray to perform that amount of itterations before finishing the render?

Thanks a lot,

Me

greymouser69

As I found recommended on previous threads the following should help:

Set max time to 0 (infinite rendering)

Turn off Quality so it doesn't calculate convergence

Control the render with the max samples setting (I use 5000 but you may want higher depending) and remember you can always stop it when it looks good enough for you.

Edit:  Another thing I try to do is render at 2x the desired resolution and resize/down sample in an image editing package like photoshop or gimp.

gibrril_fa945a6cee

Hi,

Thanks for the reply!

I'm using batch rendering, so most of the time my PC is rendering while I'm away (or sleeping). If I set max time to zero, will it ever stop and start on the next scene?

hphoenix

Unfortunately, there is NO single 'optimal' set of Iray settings.  They will vary from scene to scene, due to lighting, surfaces, reflection/refraction/emission, and more.

If max_time is set to zero, then the other two parameters (iterations and convergence) will still potentially stop the render.  If you set the iterations to zero as well, ONLY convergence percentage will allow the render to complete.  If all three are disabled, then the render will continue until you stop it (or it crashes.)

Usually, if you are concerned with grain in the resulting render, it either needs (1) better lighting and tone mapping or (2) more iterations/higher convergence ratio.

Photographic grain is realistic, when lighting isn't sufficient for the ISO/exposure/fStop settings.  Better to create the scene so that it is well lit, then use colored lighting (as appropriate) and either post-process the dimness, or adjust your tone-mapping down.  But get the lighting right first.

 

gibrril_fa945a6cee

Thanks for the replies! I' using HDRI lighting in combination with one distant light in this case.

gibrril_fa945a6cee

So Basically if I put convergence and max time to zero and put the itterations to 2500, every render will stop after 2500 iterations?

Kevin Sanderson

Turn quality off, set max time to zero and set your iterations (max samples) to where you want it to stop. It does stop there.

gibrril_fa945a6cee

Thanks a lot,

That does the trick indeed!

SpottedKitty

A couple of things to keep in mind — in an Iray render, the surface materials and the lighting setup is even more important than in a 3Delight render, and even more sensitive to getting it "not quite right", so you will end up tweaking settings a lot. Also, an Iray render doesn't run once and it's finished, it keeps running until it hits one of the three stop condition limits (time, iterations and convergence %). The render will stop whether or not the materials and lighting are "not quite right" enough to prevent the render from looking good.

gooseport1717

greymouser69 said:

As I found recommended on previous threads the following should help:

Set max time to 0 (infinite rendering)

Turn off Quality so it doesn't calculate convergence

Control the render with the max samples setting (I use 5000 but you may want higher depending) and remember you can always stop it when it looks good enough for you.

Edit:  Another thing I try to do is render at 2x the desired resolution and resize/down sample in an image editing package like photoshop or gimp.

How do stop a render?

gooseport1717

Hey how do you stop a render from rendering. I have a image that been rendering over 7 hours now.

rbingham2000

Stopping the render is as simple as hitting Cancel on the rendering dialog box in Daz3D once you feel that things are done to your satisfaction.

SpottedKitty

Either that or hit the <Esc> key. Note that this isn't instant; the render has to finish its current chunk of data. I've seen it take anything from a few seconds to a minute or two, depending on how much data your computer's juggling.

Bobvan

I always max it out. Habit I got from Lux rendering..

Drip

Basically, a render should stop when one of the following happens:

1. Maximum render time has been reached. Pretty straightforward, use this only if you simply don't want your computer to spend more than an X amount of time on a render.
2. Maximum amount of samples has been reached. Pretty similar to the previous, but instead of limiting by time, it will stop when an X amount of samples have been made. IMO only useful for testing purposes.
3. Quality/Convergence ratio has been reached. This is the *only* setting that controls what quality is acceptable for ending a render. If you want a crisp render with almost no visible grain, no matter how long it takes, be it 5 minutes or 5 days, then you'll want to fiddle with the Convergence Ratio. It's 95% at default, but there can be a noticable improvement from setting this to 99.5%. Just be warned that that last 4.5% sometimes takes as long as the 95% before it!  The higher convergence you reach, the less grain your image will have.

Whichever of these things happens first, will stop the render.

You can disable any of those requirements, but that will mean the render will go on forever unless you manually cancel it.
Reaching the maximum render time or maximum sample count does NOT imply that the maximum convergence ratio has been reached. Far from it, it depends entirely on the complexity of the scene. The more complex the scene, the longer it will take to reach a high convergence ratio, which means that a low render time or a low sample count cut off the sample at a low convergence.

Probably the most common combination of these settings is Render Time with Convergence Ratio. Which basically means you want DS to try and reach that 99.5% convergence ratio (A), unless it takes longer than 2 hours (B). Ideally, A happens before B happens. Optimizing your scene (removing unnecessary things that make it more complex or reducing the complexity of things that are necessary) go a long way to accomplish that.

dllazarus

Excellent info here.  Thanks.  As someone between beginner and intermediate, can you also give "best practice" settings for the IRay progressive render settings, alpha, optimization, filtering and other parameters?  Something akin to what adamr001 did here:  https://www.daz3d.com/forums/discussion/16085/render-profiles-for-daz-studio-4-5/p1 for 3Delight renders would be awesome.  Thanks again.

Ghosty12

Don't forget that you also have filtering as well which helps a lot.. On reading a post in another thread about speed and so on, and for what images I do I set my max samples to 1000, and use the filtering settings in the image below..

Setting it to 200 gives the GPU time to get a decent render going before it starts grain/firefly removal..