C4D commandline .ass export very slow

[marc_angele1]

hello guys,

i have a scene with three character full of fur, made with c4d hair. everything works fine until i want to export the scene as .ass for my renderfarm. i use for that the command line option. here my command:

c4d -nogui -arnoldAssExport scene=currentFile;filename=assName_####.ass;compressed;exportType=0

it takes over an hour to write one frame to disk. why is it so slow? what could be the problem?
what kind of resources is needed for the export? CPU, RAM, DISK? how can i make my machine faster?

if i start the IPR it only takes 5 minutes until the export is done and the render starts. and if i start the normal picture viewer it takes 20 minutes to start the render. why are there so big differences?

i'm testing now to the workflow to rendering with c4d command line and not with kick. but actually i don't want to buy c4d command line licenses, as well. and if it takes there 20 minutes there as well, it is not a big help...

many thanks for any help!!

best marc

[peter.horvath6V6K3]

Do you have the same export time when you do it from the GUI (via the Scene Export dialog)? Do you export to a local drive or a network drive?

[peter.horvath6V6K3]

I guess the difference between IPR and PV is coming from Cinema 4D. When you render to the IPR, it has no overhead, the active editor scene is just exported to Arnold. However when you render to the Picture Viewer, cinema first clones the whole scene (to be able to work on the original scene while the render is running in the background) and then the cloned scene is exported to Arnold.

Actually the same happens when exporting the scene to ASS, the scene is cloned first. The time difference (compared to PV) may come from writing to the disc, but it still seems to be too much.

[marc_angele1]

hi peter,
thanks for your answer and your explanations!

oke, so in best case it should take the same time like in the PV. i keep testing.

i exported it to a network drive, but it is connected to with 10GbE and faster than my local drive.

i tested the GUI dialog but canceled it after 15 minutes. i do a test again and poste the result. maybe it takes an hour until i can give you an answer.

thanks a lot!

marc.

[peter.horvath6V6K3]

I can also add a new flag to the command line to prevent cloning of the scene. Although there could be cases where it does not work properly, because Cinema also does some extra evaluation on the scene. But maybe it could speed up the export in your case, something closer to the IPR result.

[marc_angele1]

hi peter,

so, i made a few more tests:
i used the arnold scene exporter and it took 58 minutes. pretty much the same like the command line export.
i tested to render the scene with the c4d command line renderer, there it started after 15 minutes. this result is not so bad, but it makes my workflow more complicated.

if you could add a flag to prevent the cloning, that would be great to test!
any step to get closer to the IPR result (5 minutes) would be a big help 🙂

thank you!

marc.

[peter.horvath6V6K3]

I just realized you have lots of c4d hair in your scene. Cinema calculates the hair simulation when the scene is cloned, before the render starts, that takes so long. The 20 minutes in PV makes sense then, 15 min from C4D cloning and calculating hair + 5 min export to Arnold. I'm still not sure why writing to ASS is so slow though. Did you try writing to a local drive instead of a network drive?

About experimenting with the new flag, could you please send a mail to support(at)arnoldrenderer(dot)com and tell the guys to forward your request to me?

[peter.horvath6V6K3]

Another idea is to export to USD. USD may have some limitations, so I'm not sure it can support everything in your scene, yet I wonder whether writing to USD instead of ASS is faster.

[marc_angele1]

definitely the fur is the problem. if i disable it, it only takes a few minutes.
wow oke, c4d calculates all the hair on every frame form 0 to the one to export. since my frame range starts at frame 1001 it calculates all the 1001 not animated/empty frames from 0 to 1001. even without any dynamics! sure this is more an c4d issue, but do you have any idea to prevent that?

yes, i will send an e-mail to support. what should i write in this e-mail? just the request or do you need an example scene?

[marc_angele1]

i never worked with usd. is it working like a ass-file? can i just render a usd-file instead of a ass-file? and can i replace values at rendertime with the kick command flag -set ?

[peter.horvath6V6K3]

Don't really have any idea to prevent C4D doing that. I have some vague memories that it's not possible, but you can ask the Maxon support to be sure.

Just the request is fine, so I can send you a custom build with the flag to experiment with.

[peter.horvath6V6K3]

Yes, it is working like an ASS. USD is fairly new, so there could be some limitations though. I think it worth a try to see how it works in your scene.

[peter.horvath6V6K3]

I did some tests of exporting without cloning the scene, but it did not help, Cinema still has to simulate the hair. I could not find any options to prevent it from doing so. What can speed up the export though is caching the hair. Did you try that?

[marc_angele1]

hi peter,
sorry for my late answer! i was very busy the last week.

so, if you tested it already to prevent the cloning, than i don't need the custom build and i don't send the request to the support e-mail, right?

i didn't cache it. i'm not using any simulation. it is just a static hair applied to an alembic. i will try it right now. maybe it helps.

and i will write the problem in the c4d forum. maybe the guys there can help me.

many tanks again!

[peter.horvath6V6K3]

Right, the custom build won't help unfortunately.

[marc_angele1]

the caching option is disabled if i don't use dynamics.
unfortunately this won't help as well.

the biggest issue is that c4d calculates all the "empty" frames form 0-1001 if my frame range starts at 1001. i tested it with starting frame 0 and it was at 15 minutes. unfortunately it would be very complicated to offset everything. i hope the c4d guys can help me with it and c4d starts the calculation only at the starting frame of the sequence.

[Yarsolav_Ya]

Have the same problem.

Render the hair in C4D Picture Viewer leads to very slow phase of "exporting", contrary to exactly the "rendering" phase. When the total frame takes 1-30 min, the exporting only takes 1-15 min, and only 15 seconds for a render.

Also the PC resources during the "exporting" is almost not used.

It would be cool to find a way to speed up the "exporting" phase.

[peter.horvath6V6K3]

As of the previous discussion, the overhead might come from the Cinema 4D Hair simulation, calculating all frames from frame 0. Do you have similar render times if you use a different renderer (e.g. Standard/Physical)?