Hierarchy

Overview

This capability provides requirements for the scene graph organization (prim hierarchy) of USD assets. The prim hierarchy facilitates data organization, composition, traversal, inheritance of computed properties, transformation and other operations. Careful consideration of the prim hierarchy is therefore vital for successful use case enablement.

Note

This capability in particular is a work in progress and will be updated over time.

Requirements

Tags	Summary	Compatibility	Validator
🔑	All prims in the hierarchy must be direct or indirect descendents of a single root root prim.	openusd
🔑	Stage must specify a default prim to define the root entry point.	openusd	latest+
🔑	All prims representing objects or groups that require placement, posing or animation shall be xformable.	openusd	Manual
✅	The root prim of a placeable asset shall be an Xformable prim (i.e., a prim that inherits UsdGeomXformable, such as Xform).	openusd
✅	Transformations on prims that are intended to be translated, rotated or scaled by users should conform to the UsdGeomXformCommonAPI.	openusd
✅	For articulated assets without joint definitions, the prim hierarchy should reflect the kinematic chain.	openusd
✅	Geometry should be grouped in a way that is logical for the object’s structure.	openusd	Manual