"degenerate polygon objects found in frame: x" error from alembic file

[JakobAppleby]

Hey i have this problem with an Alembic file from Houdini.

Its a debris sim with quite a lot of objects, but all from 8 instances. For some reason i only get to render the first frame they exist, then on the later frames i get "degenerate polygon objects found in frame: x" in the console

C4D viewport and a normal render can see all the debris, all frames.

[peter.horvath6V6K3]

Can you send me the Alembic file or just a simple one with the same issue?

[JakobAppleby]

Yes ill see what i can do, right now its too big to send.

[JakobAppleby]

Bit too big to upload here but you should be able to grab it here:

https://www.dropbox.com/s/5zpis1us9ke1k8a/debris_cachedsim_fewerframes.abc?dl=0

Its 24 fps, things start spawning at frame 12, and all other frames fail to render them, even IPR.

(It doesn't spawn near the axis)

[peter.horvath6V6K3]

This alembic file is not rendering for me at all and if I move to frame 10+, then I've got a different warning:

C4DtoA | 00:00:53   697MB  WARNING|   resetting parameter vlist on /RBD_Main_sim/Debris_sim_Out_4 (found: nans or infs)

The native loader has no problem with it, so something's definitely not right in the Arnold alembic procedural.

[JakobAppleby]

But you see them in viewport at frame 12 at z -600 ish? And you can render them with physical render?

I wonder whats up with that.

[peter.horvath6V6K3]

Yes, using the native importer I see the objects in the viewport and in the Standard/Physical render. As the warning says, there are some invalid values in the vertex list coming from the Alembic file. Maybe it's something wrong with the sim?

[JakobAppleby]

Alright, ill see if there is anything i can do to make it work on the output in houdini.

[JakobAppleby]

Im at a loss here, cant seem to find any parameter that affects this at all, be it packed objects or not. Might be something that comes from the instancing of the different types of debris onto points in houdini. Need to find a workaround for that to even test it

[JakobAppleby · Accepted solution]

Hey, fixed it! Using a clean node in Houdini lets me delete "NANs"

Made them show up each frame now

[peter.horvath6V6K3]

Glad to hear you could fix it. Could you please check if the alembic Arnold Procedural object can read and render the fixed file? Or if you can send me the fixed file, I can check myself.

[JakobAppleby]

Yeah the Procedural object renders it too

[peter.horvath6V6K3]

Thanks for the confirmation.