2 days 17 hours to render a 2048x2048 image. How can I fix this?

[AC5L4T3R]

Hello all!

Over the weekend I sent a job to our farm to render an 8k still which was split in to 9 tiles and rendered on 9 machines. The quickest rendered in 11 hours and the longest was 2 days and 17 hours. This is obviously way, way too high but I'm not sure how to go about lowering the times.

My scene is in a tunnel where the walls are covered in giant glass panels which have lights behind them, as well as on the ceiling of the tunnel. I can't show it because its under NDA.

Here are my current settings. Pretty much default except the min and max subdivs. Any advice would be much, much appriciated!

Edit: Just realised in my screenshots I have the primary set to Brute Force, but was rendered with Irradiance Map

[jacksc02]

BF/LC might be quicker.
Also why break it up into tiles when you can use DR?
4/64 for AA is pretty extreme. Is there a need for 4 min samples?
You may also want to update to the latest official build 3.60.03.

[AC5L4T3R]

BF/LC might be quicker.
Also why break it up into tiles when you can use DR?
4/64 for AA is pretty extreme. Is there a need for 4 min samples?
You may also want to update to the latest official build 3.60.03.

Max is crashing when I use DR, I'm not sure why but it's something I have to look in to once I have time. I haven't test a min of 2 samples but on default I get a lot of fireflies closer to the camera.

[Neilg]

Jesus christ your AA is a bit high.
bring min samples to 8, noise threshold to 0.01, AA down to 1,4 and start raising the min. shading rate to remove noise. Right now you're forcing the AA to resolve everything instead of allowing all the systems within vray to compliment each other & work efficiently.

[AC5L4T3R]

Jesus christ your AA is a bit high.
bring min samples to 8, noise threshold to 0.01, AA down to 1,4 and start raising the min. shading rate to remove noise. Right now you're forcing the AA to resolve everything instead of allowing all the systems within vray to compliment each other & work efficiently.

Thanks Neil, I'll give it a go and let you know! I guess I need to revise my knowledge.

[AC5L4T3R]

At what point would I start raising min samples/noise threshold/AA? I'm on 48 min shading rate now. Took 7 mins to render at 1500x1125 with a min rate of 8 and 20 with a rate of 48. Currently my sample rate looks like The Predator is about to have a field day.

[Neilg]

The sample rate render element? that's not such a bad thing, you're not after a completely flat image. Is it noisy when you look at the base render?
You can start increasing other settings again. put noise threshold back to 0.005 etc. Usually I don't need to which is I suggested to raise them to let the shading rate kick in. You can nudge your AA up to 1,6 or even a hair higher if the scene calls for it for example, I just gave you the settings that work well to start moving up from.
hard to say more without seeing it. there could be some things you could do on the material side to optimize it - you say it's lights behind glass, have you tried excluding the glass from the casting shadows/gi, having a 'visual' setup and a 'lighting' component that exist independently of each other, there's also things you can do with the override material to optimize etc.

[duke2]

Your AA settings are insane. Keep the min at 1 and tweak the noise threshold.

[svetlozar.draganov]

If tweaking AA alone doesn't get speed improvement you are looking for I would suggest to restore default render setting and to only chance something if necessery.
If you got artifacts like fireflies you may also send them for investigarion, there might be another way to resolve them besides cranking up AA.
Regarding DR crash, this is also something we have to look more closely so when you have time open a new thread or contact us at support@chaosgroup.com about that.