Arnold render time increases with increasing frame number

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Maja Divjak asked · Dec 03, 2020 at 04:01 AM

Arnold render time increases with increasing frame number

Hello there,

I have a complex Maya 2019 scene with lots of cached nParticles, some caches offset in time, lots of polys and 5,000 frames. There is a Skydome light and two spotlights. Given the complexity of the scene, I can jump around in the timeline and the viewport will update in about 2 minutes. My problem is that the time between Arnold renders gets longer and longer with increasing frame number. Its as if Arnold cycles through the caches to the designated frame and then starts the render and then repeats the process for the next frame. This happens with one-off renders in the render view and using Render Sequence. I don't have an Arnold license, so can't try batch rendering.

Some stats: at Frame 300, the total render time is 12 minutes and the actual render time is 6:59. Render view and viewport are matching.

At frame 3,000, the total render time is 32 minutes and the actual render time is 5:57. I've also noted that at frame 3,000 the viewport and the render view do not match. Interestingly, if I fire off a quick Maya software render, it starts immediately and the viewport and render view match exactly (although you can't see the nParticles). A playblast also matches the viewport exactly.

I've tried disabling the particles in the particleShape node, so they are running only from the caches and I've tried resetting all caches to frame one, with absolutely no effect. Turning off one of the spotlights barely affects render time.

My specs: Maya 2019, MtoA 4.0.3.1, Arnold Core 6.0.3.1

Intel Xeon CPU E5-2687W v4, 3GHz, NVidia Quadro P5000 graphics, 64GB RAM

Arnold log is attached.

If someone could please advise what the problem is as a 30 minute wait between renders is untenable and I'm at my wits end as to what to do.

Thank you in advance,

Maja

arnold.3000.txt

arnold mtoa

arnold3000.txt (37.4 KiB)

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Answer 1 · 2021-01-13T00:05:10Z

Maja Divjak answered · Jan 13 at 12:05 AM

Hi there,

Still waiting to hear anything on this please? Any chance of an update as to progress?

Thanks so much and best wishes,

Maja

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Stephen Blair ♦♦ · Jan 14 at 11:39 AM

Issue is logged. As I wrote before: There's no ETA on this. I'm pretty sure it won't be in the next update.

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Answer 2 · 2020-12-11T06:57:31Z

Maja Divjak answered · Dec 11, 2020 at 06:57 AM

Thanks for letting me know. This seems like quite a serious issue to me- is there acknowledgement that it will actually be attended to and hopefully fixed please?

Thanks so much,

Maja

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Answer 3 · 2020-12-10T12:44:13Z

Maja Divjak answered · Dec 10, 2020 at 12:44 PM

Hi Stephen,

Just wondering if there has been any word on this as yet please? Do you have any idea at all how long this might take?

Thanks so much and best wishes,

Maja

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Stephen Blair ♦♦ · Dec 10, 2020 at 01:12 PM

There's no ETA on this. I'm pretty sure it won't be in the next update.

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Answer 4 · 2020-12-07T21:26:09Z

Maja Divjak answered · Dec 07, 2020 at 09:26 PM

Thanks Stephen,

Much appreciated. I know this is a bit like asking the length of a piece of string, but do you have any idea how long this will take please? Days? Weeks?

Thanks so much and best wishes,

Maja

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Answer 5 · 2020-12-07T01:58:49Z

Maja Divjak answered · Dec 07, 2020 at 01:58 AM

Hello there,

I believe I have confirmed this is an Arnold problem. I just installed RenderMan and found that it does not cycle through the caches to render frame 3,000. It starts almost immediately, like the Maya software renderer does. In the interests of time, I would be tempted to go with RenderMan, but I'm not familiar with it and it will necessitate redoing the shaders, most of which are cached (Arrgh!) and redoing the lighting. If there is a solution to this problem ie some way of preventing Arnold from cycling through the caches, that would be absolutely fantastic.

Thanks so much and best wishes,

Maja

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Stephen Blair ♦♦ · Dec 07, 2020 at 03:36 PM

It an MtoA issue, and I've logged a ticket for this. I don't see any way to work around it.

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Answer 6 · 2020-12-05T07:10:37Z

Maja Divjak answered · Dec 05, 2020 at 07:10 AM

Hi Stephen,

Thanks for your reply, much appreciated. Interesting, I wonder why it's doing that too. Weird.

Yes, if I change to Ass and Kick, it still takes about 27 minutes to render. If I switch to Export Ass, it crashes Maya. Interactive is about half an hour or so, as before.

Thanks so much and best wishes,

Maja

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Answer 7 · 2020-12-04T15:45:45Z

Stephen Blair answered · Dec 04, 2020 at 03:45 PM

I've been testing nParticles, and it looks like the cache files are always read from the start when I render (for example, if I render frame 120, then the caches for frames 1,2, .., 120 are read).

Yet the MtoA code explicitly says "do not read from start" when it calls the Maya API, so I don't know why this is happening.

If you change the Render Type to Export ASS and Kick (Render Settings > System tab), does it still take as long to get to the rendering part?

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