alembic import (update) workflow

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Old 06 June 2012   #1
alembic import (update) workflow

Hey guys, has anyone done much with the alembic importer yet? I've got a hypothetical workflow where an artist has recieved v001 of a cache, done some work with it (shaders, potentially new attributes, connections) and then recieves an update in v002, and wants to replace v001 while preserving all work they've done. I suppose I'm after something that would work similar to a standard referencing workflow - but the Abc importer actually creates the nodes in your scene, so I'm not sure how to replace them and account for all possible edits that could have been made.

I could (and will, if nothing better comes up) just import the ABC in a maya scene and reference that in to my lighting scene, but that seems like an unnecessary additional file that needs to be saved to disk.

Any thoughts, suggestions would be greatly appreciated!
 
Old 12 December 2012   #2
If we pretend that alembic cache brings the animated geo only so we have to shade + light + render I think there are couple of solutions.

It seems reasonable to reference an alembic cache (maya) scene and basically the scene we save will contain shade + light + render information.

For me the main problem as far as I see alembic does not store namespaces (despite the option 'Strip Namespaces' turned off). So I really don't know which asset is the alembic geo object. And it causes name clashing because maya only rename automatically nodes at the same level.
 
Old 12 December 2012   #3
Good question

We've been moving our pipeline towards Alembic and really like a lot of it.
We are still looking at the best way to "version up". If the nodes are all named the same and you haven't added/removed anything you can just change the path on the alembic node...and then save your file and reload the scene. We haven't discovered a way to force a reload. I read somewhere that this connection is purposefully 'not live' to speed things up...and alembic is fast.

I've been mulling over the process of building a script to import the new alembic cache and compare changes, added connections and what not and rebuild...but that is a bit of an undertaking. Fortunately most of the stuff is connected cleanly to that alembic node...so it should be possible with enough time.

Good to get a discussion going at least.
 
Old 12 December 2012   #4
Thanks for the input! I had a similar thought about a script that would look at new attributes and connections, and yeah its a bit of a pain. Im trying out an approach now where I load the alembic file in to a maya 'Asset', exposing only the nodes and/attributes that are necessary to manipulate the cache - The idea being that it should be _much_ easier to analyse/preserve the modifications made in the production scene. So far we havent had need to use this extensively, but Ill happily update here when I know how successful it is.
 
Old 12 December 2012   #5
The way we do it, is that we have a shaded asset and then with Shotgun, we can load that in the scene. If there is an alembic file that has been published by our animators, we can attach that to the shaded version.

This is really handy since you can easily go back to the original shaded version or the animation and make changes, and just press the update button.

If our assets are up tp date there is a green button. If there is an update it will turn yellow. And
i guess if something is not working correct it turns red.
 
Old 12 December 2012   #6
So it seems nobody have problem with disappearing namespaces!?
I just export an alembic file from a scene with a couple of referenced characters (of course they have namespaces) and when I open the alembic file and the top nodes of the rigs are named like Root, Root1, Root2, and they should be like namespace1:Root, namespace2:Root, namespace2:Root. How? Why?
 
Old 12 December 2012   #7
Actually we did run into that.
I think I remember reading that maybe an updated version supports namespaces...or at least I know it said SETs and Lights...maybe not namespaces.
But yeah, namespaces in maya are weird.
We had to build some scripts that query if there is a namespace and then store it in a master metadata json dictionary (Along with character SETS) that we can use to create the namespace before importing the Alembic file. If you create the namespace in the scene before you import the file I've found it assigns the namespace correctly on import.
Just check out the maya command ref on namespace commands to see how to create a namespace.
It is super easy.
Hope that helps.
~Ben
 
Old 12 December 2012   #8
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