USD files can be opened in procedurals. HtoA supports USD (.usda, .usdc, .usd) files using the arnold_procedural OTL.





Object Path




Override Nodes 




Overrides the values set within the USD file.


Operator Graph

You can choose to connect any existing operator graph to a procedural.

To connect a Procedural Operator to an Arnold USD, you have to pick the operator ROP in the Arnold properties of the Arnold USD. Use the Arnold Properties top-level Arnold | Operator Graph parameter to pick the operator ROP, which can be anywhere in your scene.

Procedural Operator parameter in Arnold properties of Arnold USD

Viewport Proxy


Reads the bounding box from the Geometry File. This will only work for .obj and .ply files. Bounds for .ass files will be displayed if an .asstoc file is found alongside the .ass file. 

Target SOP

Use an object in the scene to attach as a bounding box preview. 

Display As

The assigned file can be displayed as Global Bounding Box, Bounding Box per Node, Points, and Polygons.

Proxy SOP

Provides a bounding box representation for visualizing the contents of a procedural when importing geometry into Houdini using a SOP.