Hi there,

I am trying to figure out why I can't get all of my simulated curves cached in an alembic output. They are vellum cloth curves simulated continuously. First time using this feature..
But only the first "instances" of these curves come out in the alembic file.
Any idea of what I am missing in my tree?
I tried to convert them to different type of curves but nothing does it. If they are strips of polygons they get exported correctly.

Thanks

Try enabling Initialize Simulation OPs on the rop_alembic1 node.

your file seems to work fine
it loads all the curves back using Alembic SOP

just guessing here, but it's possible that you are trying to load the alembic using another software like Maya which in the past had issues with having more curve primitives in the same shape
so for that you may need to segment all the curves into object per curve
for example using Enumerate SOP (Type: String)
and in ROP Alembic (Build Hierarchy From Attribute: check, Path Attribute: index)

or maybe you can check your other software for import options, if using Maya, you can probably import your original abc through Bifrost just fine

EDIT: ah maybe this is not the case as you mentioned: "only first instances load", I understood it as only one curve

Good morning,

Thank you both! Sorry I did not see your replies on Friday (I wish I did..). I am back at this this morning.

Enivob, the "Initialize Simulation OPs" did not work unfortunately.

Tamte, this idea worked. Indeed I am trying to bring this in Maya after export. And the enumerate + build of hierarchy did it! Although this makes an hefty alembic as it creates one object per curve.. But loaded in an Arnold stand-in it seems to cope with it.

That Maya is definitely struggling with the new shapes created at simulation (with the continuous feature) in the Alembic. I did try as much as I could to reconstruct these curves after simulation but I did not find any solution. The enumerate + hierarchy forces it in the alembic at least.

Thank you both ever so much.

It is a very expensive cache to do though. I guess it has to go through all and each individual shapes.
Any extra ideas to throw in? Do you have an equivalent route to the enumerate so that Maya will recognize all the curves, but, without the alembic having to write them as separate shapes?

Hope that makes sense..

I'd not advise to do that, as indeed it's a ridiculous thing to have to do, I just know Maya used to have this limitation about curves, which I thought it may be already solved using xgen or something, but I don't know

However since you mentioned Arnold standin, I'd expect it should be able to read your original file as there was nothing wrong with it and came back to Houdini just fine
Or as I mentioned try loading it using Bifrost, which can also circumvent Maya and render directly in Arnold as a procedural

Or try USD?

The original file didn't seem to work in a stand-in either.
I never loaded an alembic through Bifrost. I wasn't aware of this method. I will give it a go at some point.
USD's definitely sounds like the best route as the studio I am in is trying to implement it inside our pipeline. It looks like an awesome bridge between 3D platforms.
Thanks for your help.

As others have said def go with BF Graph route, easy to read attributes and transfer stuff back and forth. Besides the alembic is extremely fast to read the data as well and if you render with Arnold is all procedural. Here is a quick setup. On this test, I'm not using the scale attribute but you can if you set it up in H. But I'm using the velocity which BF can read without changing the attribute.