I'm having Contour filter instability after arnolds update to add GPU acelleration

[chatect]

Hey! I a bit at a loss. Prior to the update to the most recent version of c4dtoA, I have had really stable renders using the contour filter (which I use exclusively). Lately, the engine has been very unstable. And after throwing several crashlogs into chat gpt, it seems a lot of it is because of the inclusion of GPU (i think?) during the render process. I have a scene that reliably wont get past the 1st frame. 

I don't really know what question to ask other than is there a way to return to the previous CPU only render using the contour filter without disabling GPU for everything (like the IPR window?). 

Lozing hairz trying to figure this out. Any help is appreciated! 

I attached the most arnold log and also, if anyone (devs?) want to look at the scene, heres a google drive link to the c4d file: 

https://drive.google.com/file/d/1n2GhxTzn-2R5nV6zaF9dlyebUlTeP5Pb/view?usp=drive_link

It seems not to crash if I use box filter, but reliably crashes when using the contour filter.

And this was chatgpt's analysis of the log:

🧠 Breakdown of the Log

Arnold:

• Loads everything cleanly

• Finishes full BVH building with no mesh errors

• Begins rendering on GPU (log confirms RTX 3070 active)

• Starts IPR with contour filter, toon shaders, and atmosphere volume active

• Reaches:

  shell

  CopyEdit

  50% done - 24 rays/pixel

• Silently terminates after that
  (No final render, no memory error, no user abort)

---

🔥What This Means

This is another GPU memory exhaustion or driver-level stall caused by the same core elements:

Confirmed Active:

Feature Stress Level Notes

Contour Filter	🟥 High	Edge sampling via GPU now
Atmosphere Volume	🟧 Medium	Light scatter adds bounces
Toon Shaders (11)	🟧 Medium	Stylized shaders with procedural ramps
10x ramp_rgb shaders	🟧 Medium	Procedural input to toon shading, may increase edge complexity
12 AOVs	🟨 Medium	Every AOV costs memory
GPU (RTX 3070)	🟥 Bottleneck	8GB total, ~5.1GB usable per log

Im just a bit confused because this behavior did not exist prior to the most recent version of c4dtoa. Thanks a bunch! 

[peter_horvath]

There are two different issues here:

1) The scene you have shared stops after the first frame. This is caused by Magic Bullet Looks and not Arnold related. If you disable or remove Magic Bullet Looks, all frame renders fine.

2) Crashes with the toon shader on GPU. I'm not able to reproduce this with your scene. Are these crashes happen randomly or always in the same frame?

There's no option to render toon on CPU and the rest of the scene on GPU. You might need to roll back to the previous version.

[chatect]

Thank you very much for taking a look. So actually, I disabled Magic bullet looks & it still crashed on frame 1. It is in fact coming from the arnold render itself and not magic bullet (ill attach a log to the crash i just had), and it does reliably crash on frame 1. I wonder if you arent able to reproduce the crash because you have a better GPU than mine? Mines an rtx 3070 with 8gb ram. The crash log (according to cgpt) says its going above 5gb when the scene starts to render which is beyond my GPU's capabilities, which is why its crashing (i think?). But given this scenes tini size it's confusing along with the fact that prior to this version, I wasn't having any issues with this render (my cpu is an i9-13900k so it renders toon shader very fast). 

Oh and maybe i worded it incorrectly, I suppose i meant I wanted to render the entire scene w/cpu (which was the way it used to behave right? or am i mistaken?). Again i super duper appreciate you. !

[peter_horvath]

Oh, I thought you are rendering on the GPU, but I can see in the log, that this indeed a CPU render. In that case your GPU or VRAM does not matter. I still can't make that scene crash though, nor CPU or GPU. When it's crashing, do you see the Cinema 4D crash dialog, where it says it saved a _BugReport.txt file? If so, could you please go to that folder (should be something like HOME\AppData\Roaming\MAXON\Maxon Cinema 4D 2025_789E552B\_bugreports) and send me the minidump.dmp file?

[chatect]

Thank you again. I super appreciate you. (edited) * I was able to get it to generate a crashlog (yay!) from c4d. It gives me hope that you cant produce crashes, but also really confused since all these files used to be stable as recently as march. Anyway, heres a c4d log from the same file

and  google drive link to the minidump file 
https://drive.google.com/file/d/1PwwXgkCmC3lAAOCZ_LcRDKNsZAWawlJv/view?usp=sharing

[chatect]

Just wanted to update you on some things I've been trying in troubleshooting this. I opened up a new scene and made a basic cloner+cube setup with contour filter and I rendered it without a crash (about 30 frames). 

Then I imported the TV from the scene i shared here into that file, and rendered it with the cubes, same thing, no crash. 

Then I rendered the TV in isolation without the cubes, 150 frames, no crash. . . Which is great, but also confusing. The file I sent you is a file that I've had over several updates of arnold & c4d, so over the years ive saved it and gotten that *older versions wont be able to open this* dialogue (indicating you're updating the version of this file). I don't know if somehow that is causing instability or something, but rendering that TV in a bran new file hasn't caused any crashes. 
Also rendered it with magic bullet looks on and off, neither produced crashes. 

[peter_horvath]

We've seen instability issues with Intel Core 13th/14th gen CPUs reported before. Here's a description of the issue: https://community.intel.com/t5/Processors/July-2024-Update-on-Instability-Reports-on-Intel-Core-13th...

I'm wondering if your crashes are related. You can try to update your BIOS and see if the problem is gone.

If the issue still persist after the BIOS update, you can try to identify the root cause of the crash by removing parts of the scene one by one until the crash is gone. It sounds like something specific in your scene is triggering the issue.

[peter_horvath · Accepted solution]

Here's another description of the Intel CPU instability issue with more details: https://wccftech.com/intel-14th-13th-gen-cpu-instability-issues-solved-confirms-0x12b-as-final-mitig...

[chatect]

Thank you so much for these links and the suggestion.  I will get back started up this week trying to figure this out. extremely helpful you are. thank you thank you thank you

[chatect · Accepted solution]

Just wanted to update you on how things went down. First of all, again, you have been so helpful to me so many times on this forum. So thank you. 

After I talked with you I updated my bios and chipset since a lot of what you said made me think that i am dealing with some of the issues with intel processors esp the kind i have. My computer immedately went to hell after that with endless BSOD loops ranging from nftf.sys errors to literally any possible bsod error. Id have periods of stability followed by insane crashing to the point where i bought a new SSD and tried to reinstall windows (which also failed). To keep the hell i went through brief. about 20 hours later (2 full days of computer troubleshooting), begging jesus to heal my pc 😄 and switching to a slightly different bios, I was able to get my PC back up and everything stable again. I think the bios reset some settings to unstable values for my PC and was causing memory/ram issues (?). Ultimately I slotted my old SSD back in since i was able to isolate the problem (it wasn't my sSd thankfully).

And directly to the issue here, when i got c4d reinstalled, i opened the scene i sent you again, and I have been able to render it without any crashing. Multiple times, in ways that i was consistently getting crashes, i am no longer. So i think your advice was correct, and something with the way my processor now operates after the bios and chipset update fixed the problem. So again, thank you so much. I would not wish this on anyone but at least i have a little more stability now. you are an angel. thank you ❤️

[peter_horvath]

I'm sorry to hear you had to go through hell with the BIOS update, but I'm glad you could finally solve it and it seems to help your instability issues. Happy rendering!