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transmission depth takes sooooooooooooo long to start rendering in the gpu render!! (MTOA3.3.0.1)

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Message 1 of 12
ahad22896
947 Views, 11 Replies

transmission depth takes sooooooooooooo long to start rendering in the gpu render!! (MTOA3.3.0.1)

when I put transmission depth value more than zero makes the GPU render starts after waiting soo much compared with the previous release, I love arnold Gpu Beta so much It is fast and just so right !
and I hope it will get better and better with every release !

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11 REPLIES 11
Message 2 of 12
aaronfross
in reply to: ahad22896

This past week I have spent a lot of time trying to get GPU rendering working well enough for material testing. Nothing fancy, just trying to get faster previews of material editing. I gave up. Even after jumping through many hoops (pre-populate GPU cache, use all Arnold lights and materials) it still takes FOREVER to get that first pixel. Even a trivial scene with no global illumination is super, super slow to start up. It's a waste of time. I wish I had never even tried, because I'll never get all of those hours back.

Message 3 of 12
thiago.ize
in reply to: ahad22896

It will be slow (maybe up to a few minutes) the first time you render that scene as it does the just in time compilation for the shader combination that you're using. After that, if you try and re-render the same scene it should be fast. If you look at the Arnold logs with sufficient verbosity setting set, you should get messages telling you why it's slow. Feel free to post your log here so we can see what's going on. It's possible there could be a bug we need to fix...

Message 4 of 12
aaronfross
in reply to: ahad22896

A few minutes is way too long to wait for first pixel. Those few minutes add up. Pretty soon I've wasted a half hour or more of my day waiting for that GPU render.

Message 5 of 12
ahad22896
in reply to: aaronfross

yes, first time rendering takes soo long to start when you render big scenes but this problem I think if I'm not mistaken arnold promised us to solve with texture on demand loading

https://youtu.be/pQctj_5MWiY

but transmission depth even with a verybasic scene with no texture starts after so much wait !

Message 6 of 12
thiago.ize
in reply to: aaronfross

That should only happen the first few times. Then it should be fast, especially for simple scenes. Do post a log of your slow startup so we can see what's wrong and fix it. For reference, it is almost instant when I render a simple GPU scene on my machine.

Message 7 of 12
thiago.ize
in reply to: ahad22896

Please post your arnold log so we can see why this is slow.

Message 8 of 12
ahad22896
in reply to: thiago.ize

I'm sorry @Thiago Ize yes it acctually slows down just with the very first time only
but also not so long like I mentioned may be it was a corrupted scene back then I don't know !! but when I try it now it works pretty well
thank you @Thiago Ize

Message 9 of 12
ahad22896
in reply to: thiago.ize

log.txt
...

Message 10 of 12
thiago.ize
in reply to: ahad22896

Good to hear it's now working as expected.

Thanks for supplying a log file, but unfortunately this isn't an arnold log file. Some instructions are here:

https://docs.arnoldrenderer.com/display/A5AFMUG/Log Note that you need to include "Info" verbosity level so we get the timing info.

Message 11 of 12
ahad22896
in reply to: thiago.ize

thanks so much @Thiago Ize for the info I didn't have a clue about arnold log actually !!
here is my arnold log file
https://drive.google.com/open?id=1AyiYXjSw4dDVGac4Dfiqo8jFPz-Ex1MS

Message 12 of 12
thiago.ize
in reply to: ahad22896

Yup, that's the Arnold log!

We can see from the log that there was some mystery 5s delay here (would be good if arnold/mtoa could report what that is):

00:00:00   847MB         | loaded 5 plugins from 3 lib(s) in 0:00.00
00:00:05  2324MB         | [color_manager] using color manager of type "color_manager_ocio"

and then rendering started a second later (you should have seen the first pixel show up at the 6s mark):

00:00:06  2326MB         |   [gpu] building scene and compiling shaders done in 0:00.001
00:00:06  2333MB         |     0% done (0/400 sample iterations)

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