Renders are going WAY too fast!!! (Version 4.21)

JCarver

Hey guys, this is another new one for me :/. I'm trying to complete a render for the first time on version 4.21 and it takes no more than 48 seconds to finish, which is not NEARLY enough time to develop the image. I have an RTX 3070 which is a wonderful gpu, but it should not be this quick! I'm making an image at 5000 pixels tall (trying to create a promo image for a cardboard cutout). I've turned the dials to try to make it go longer. Doesn't increasing the max and min samples make a render last longer? Well, no matter what I do makes a difference. The image keeps turning out grainy and just horribly underdeveloped. I swear, I've never regretted a software update so much as I am this time. :( Nothing is going right.

Advice is greatly appreciated!

JCarver

Ok, hold on! I just pushed a bunch of the sampling dials over to the max and it rendered sharper this time, but still very fast. I don't understand this, but maybe they changed something in program to make renders work faster? I'm just confused becasue it used to take up to 30 minutes to make a huge image on my 3070. (Note: this time I'm making a png with no background objects, but still trying to create an insanely big and sharp image).

Falco

They did make some render speed improvements in the latest version, so that's definitely a thing.  

I've had mixed results with trying to use render quality to do consistent rendering quality between scenes, I've had Iray decided certain scenes were done when they were not nearly close to done.  As a result my standard workflow now is just to set every render to a certain sampling number I know will be good quality for every instance (i.e. 1500), and turn off all the quality controls and set time to 0.  That way every render will get 1500 iterations no matter what and I can be assured of the quality, and know the renders will typically take between 30 and 90 minutes on my gpu depending on the scene complexity.  

hansolocambo

Try to set Max time to maximum and Max Samples to maximum so that the render virtually never ends. And instead try to go for a Converged Ratio of 99% and a Rendering Quality of 3.00 let's say. Render should be longer. And Iray will stop it when it reaches the quality.

RTX 3090 3070 is still an excellent GPU. Time a render takes depends on the complexity of your scene. And the choices you make in the Render Settings Tab. I have an i9-12900 and an RTX 3090. And some renders I do take more than 2 hours to complete, when they were taking 5-6 hours with an i7-7800x and an RTX 2070S. If a scene is complex, render will take time ;)

NVidia has done wonders in terms of real-time 3D acceleration for games. And they were the first, over 20 years ago, to think that bringing that same acceleration to the professional world of pre-computed 3D would be great. It took a long, long time to develop that technology. Now it's here. Let's enjoy it ;)

JCarver

Thanks for your comments. Falco, thanks for letting me know you've experienced this too! This is definitely a new thing to get used to.

Hansolocambo, I'm not sure if you understood my problem but you were helpful. I don't have a 3090, I have a 3070. I just wasn't sure why it was finishing so fast without completeing the render development, but I think I fixed it by turning the sampling dials to nearly max.

It is pretty cool that the renders go much faster, fer sure!

outrider42

You make a render go almost indefinitely by turning OFF the Render Quality setting. When Render Quality is on, it uses a convergence algorithm to determine a cut off point. If you turn it off, then the render will run until it hits your time or iteration cap.

Those are the 3 stop conditions for Iray. Iray will always stop rendering when the first of those is met! So if the render quality thinks it is hitting convergence way faster than perhaps you want, just turn it off.

I am not sure how it could be faster than before, because 4.21 has been slower in almost every test I have done. I have 4.16 and 4.21 in beta. 4.21 is pretty similar to 4.20 in that regard. Are you sure your GPU was rendering before?

You can always check out the forum's Iray benchmark thread. Download the test scene DUF and fire away at it. You can compare yours to others who have posted their times.

If your character is in a scene with no background, which I am thinking is the case, 30 seconds sounds pretty possible even at a 5000 pixel size. It depends on your skin setup, hair, and clothes. Once you add a 3D background that will change. Like the one in our little bench scene. It just so happens I did that recently. I took a character and added it to the benchmark scene (removing the one the bench scene has) and cranked it up to 5000 pixels. The result was not great. It took almost 10 minutes just to hit 1%, and I have a 3090 plus a 3060 combo. So that shows just how much a 3D backdrop can change the render.

JCarver

Thanks, Outrider42, I find that info very helpful! I didn't know that about the render quality setting, so I learned something here, deffinitely. I usually put render quality at about 2. But since I made this complaint, I haven't experienced any trouble. The renders complete in a good amount of time with nice sharp results. To be honest, I'm not sure if it's working now because of the way I'm tweaking my dials or not lol. It was just really strange and alarming for those first few tries when I couldn't get the render to develop all the way. I can't remember what was in my scene though, it could've either been a full scene or just a character with no background. Nonetheless, I try to keep my scenes very light, and tend to layer rendered png images in the "photoshop" phase.

benniewoodell

Yeah, this happens to me too sometimes. I just finished a project for a client and they wanted these wide shots of the characters, so wide that they really didn't take up much of the frame at all so there wasn't much definition to render, but they wanted it to match exactly the background frame they were providing. The frames were taking about 8-10 seconds each and there was so much noise even with the post denoiser, mostly in the hair. I had to set it to 100% convergence and up the render quality to like 15 to get it to bake for like 45 seconds to where there wasn't anymore noise. I didn't realize the turning off render quality thing though, I'm going to try that next time I run into this issue! 

JCarver

Glad to hear I wasn't the only one, Benniewoodell! Yeah, it has become a new routine for me to mess with the dials, otherwise I used to leave them at default. It has been really nice having faster renders though--after I solved the issue. ^_^;