Hey everyone,

TL DR : I want to create an alembic file containing an empty group with a custom attribute that's readable in Katana

I have a question that has been driving me crazy today.
When exporting alembics from Houdini and using them in Katana, let's say I have a geometry in Houdini with this path primitive attribute : fx_grp/fx/fxShape
From there I can easily add any attribute I want to the shape, but what about adding attributes to the transform ? and to the parent group ? fx_grp and fx_grp/fx have no real existence in Houdini so I would have to create an empty primitive with a path fx_grp and then add my attributes to this primitive. The problem is, if I create a primitive in Houdini for this group with my attributes will be there in Katana but it will be recognized as a polymesh and not a group. Then I tried even when creating an AlembicRef primitive instead but it's not even recognized in Katana.

The only thing that's doing half of the work is creating a geometry node named fx_grp and exporting that with an alembic render node with Root Object set to /obj/ and Objects set to fx_grp. This gives an empty group with right name in Katana but I don't think it's possible to add attributes at the Object level.

Thanks !

AFAIK, there's no way to write alembics with attributes on transforms from Houdini.

You can with USD though.

You can with USD though

I'd love USD to be an option but our pipeline is just not there yet

Thank you for your answer, I'll hang around to see if anyone comes up with a hack. Otherwise I think I'm just going to write my attributes in a json file and read that data in Katana.