Has there been a change with 4.20 and reflections? Renders taking much longer
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Has there been a change with Iray on 4.20, I'm guessing with reflections with Iray? I have some scenes that were saved in some 4.x version, not sure which but a number of different ones as I've used a particular scene quite a bit - Space Station Living Quarters. Specifically, it's taking far more iterations for convergence.
https://www.daz3d.com/space-station-living-quarters
I have made a few changes, which weren't too impactful prior to 4.20 - I changed the window material to glass using the Iray Uber shader. Then I added a large screen and set it emissive for a space background. You can see from the attachment it's run 5600 iterations for only 25% convergence. It is a big render at 5160x2160, before I was rendering 3840x2160 and I haven't seen much difference with other scenes.
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Emissive surfaces which are not fully opaque have changed, the luminosity is now reduced by the opacity value, but I suspect the issue here is simply that your GPU driver is too old (or, worse, that your hardware is too old) for the new version of iray. What GPU do you have, and what driver version?
Actually pretty new stuff... two RTX 3090's and running driver 512.59 released 4/26/2022.
Yeah, 3090 here, but old hardware otherwise, same driver
I found disabling caustic sampler decreased render times/sped things up a little
Is it the "game ready" or "studio" driver? I learned there's a difference when I installed my new RTX 3090 the other day. The "studio" driver is for rendering.
Game ready... from what I heard there isn't too much difference, the studio drivers are aimed at creative applications but the game ready is updated more frequently.
I might have to try though, to rule that out.
The benchmark thread shows DS renders slowed down quite a bit for 3090's for some reason compared to 4.15, 3070TI slowed down a bit too.
I went ahead and loaded up the Studio driver and rebooted. No difference.
I don't think it's a driver issue, as it appears to be cranking out iterations at a good pace, but the convergence is very low. If you saw the render, even though it's 5600 iterations, it's only 25% converged and still looks grainy.
Sorry if you've already checked these, but it's good to get the basics out of the way.
Has your large screen blocked any lights?
Check the log and see if the render has fallen back to CPU. Perhaps the increase in resolution was enough to push it over the GPU memory limit.
Thanks for replying but no, it's still using the GPUs, I have looked at logs too. The screen outside isn't blocking any lights or emissive surfaces. For the Environment I am just using a rough HDRI, it's not rendering the dome.
If you look at the image, it's cranking out Iterations at a good pace, it's just that the convergence is very low - normally 5000 iterations would do for many scenes.
from the bit of the render that can be seen, it looks very dark!
Do a tiny render to check the lighting
I went through the materials and found they were a bit of a mess. I don't think that would be the main problem, though a few had Refraction turned on where the object was meant to be solid.