Houdini: Rotation attribute Export For Packed Alembic Workflow

Importing/exporting assets from Houdini using Alembic with packed data is a popular workflow, though rarely discussed. Here’s a file to streamline your work and make adaptation easy.

This template file shows how to properly export packed rotation data from Houdini’s Alembic workflow to other programs like Maya, Cinema 4D, or Blender—using a packed, animated imported asset.

Why does this work? Houdini has two packed geometry types: Packed Geo and Packed Fragment. Only Houdini understands Packed Fragment internally, so we’ll use Packed Geo for exporting. Inside every packed primitive is a read-only set of matrix values called intrinsics, which can be converted to transform and pivot rotation—formats DCCs like Maya, Cinema 4D and Blender can read easily.

Demo contains both still object and animated geometry:

• Simple VEX snippet that reads the intrinsics and writes them into the proper point attributes for you.
• Simple SOP method , no-code: Use Extract Transform, enable copy pivot and orient attributes on Transform Pieces node. Export that setup to animated Alembic.

This is similar to exporting an RBD-packed bouncing box—you capture only the transform and pivot, apply it to the animated asset, and export. It works exactly as you'd expect. Screenshot with the ship asset, then apply bounding box, apply the workflow above.

Surprisingly, this method isn’t widely shared online, even though it’s a staple in real-world production. Maybe it's considered "old school," now that OpenUSD is becoming the new standard—but it's still incredibly useful.