Slow GI Precomp and Even Slower Initial Pass

[apjasko]

Hello,

I'm currently trying to render a dusk, exterior scene. I'm experiencing extremely slow precomp and render pass times. This is very strange because prior to trying to render for production, I was able to render the same file, at any resolution, rather quickly. I restarted my computer to prevent a restart overnight due to updates, installed whatever Windows updates were available, and now I'm unable to render my file.

I'm currently using Windows 7 Professional, 3DS MAX 2014, and the Aug.19.2016 Daily Build of Corona. Attached is a screenshot of my stats from the VFB. My machine is running 2x Xeon e5-2680 v2 processors, 64GB RAM, and a Quadro K5000.

The only thing I could think of that could be the culprit is my multiple ForestPack objects. However, this scene was rendering perfectly fine prior to restarting. Even with an interactive viewport to correct lighting values (scene originally created for V-Ray 3.3). I tried running the same build of Corona in MAX 2015 but still with no luck. Tried PT/UHD and PT/PT, no improvement. No errors from Corona. i'm going to try running the 1.4 build once my IT guy gets in this morning (damn work computers and locked up privileges). Maybe that will help the issue?

I can provide more information if someone can direct me how.

[Ondra]

what is the CPU utilization? Any 3dsmax photometric lights in the scene?

[apjasko]

Do you mean the load on my CPU's while rendering? During the precomp phase, it bounces between 8%-20%. I cancelled the rendering before checking the task manager. And yes, there's 6 photometric lights using CoronaShadows.

[Ondra]

ok, try removing those, they sometime make rendering really slow with many-core CPUs

[apjasko]

I'll try that. But again, this problem wasn't happening before restarting. Everything worked great following a scene conversion. Closing and reopening the file started the issue. Will report back shortly.

[Ondra]

Well, that is 3dsmax for you ;) There is really high chance this is the cause of the problem and removing the lights will help

[apjasko]

Interesting. Turning off the photometric lights did the trick, but also my CPU load seemed capped around 20% with these lights on (typically hovering around 9-10% though) and with them turned off the load will hover around the same 10% range but would spike over 50% load. I'm guessing this is the issue you were referring to about the photometric lights + many CPU issue? Anyway, the precomp is back down to a reasonable and familiar minute and a half. Thank you so much for the help!

[apjasko]

I have done more testing with photometric lights off and wow, I can't thank you enough. My gi precomp is down to 28 seconds! I'm very new to Corona (switched just this weekend from V-Ray) and am so impressed with the product thus far. You guys have done such an amazing job and I look forward to seeing how far it goes.

[maru]

Ondra, maybe there should be a warning when native max lights are detected?

[Ondra]

maybe, if we determine when exactly they start acting this way. Just putting blanket warning on all uses could make users start ignoring warnings

[apjasko]

If it helps, I was using 13 photometric lights and getting this behavior.