In HtoA, you can export any object as an archive node (also called proxy or placeholder). A Procedural references an .ass file on disk (or other procedural formats supported by Arnold such as .obj.dll, .ply, etc).


Arnold Procedurals can be created by tab-typing Arnold Procedural or Tab > Arnold > Arnold Procedural at the OBJ level. The procedural node can be used to load an external geometry file or a compiled DSO (Dynamic Shared Object).

Geometry File / DSO

The path to the geometry file (obj, ply or ass) or program to be loaded.

Display As

Assigned file can be displayed as Full Geometry or Bounding Box.

It is not currently possible to preview geometry for ass files in the viewport. 

Bounding Box

Contents (Default)

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.


Specify the min and max corner of the bounding box explicitly.


Bounding box has no defined end. Padding is therefore disabled.

Load At Init

Load the procedural contents at initialization, prior to rendering, instead of expanding upon ray hit.

Bounds Padding

Adds extra area to the edge of the bounding box. The extra bounds are displayed with light blue corners. 

Data String

This string parameter is used to pass parameters that are parsed by the procedural program and can be used for its creation/initializations. The format of this string is not standard and is dictated by the particular implementation of each procedural program. A better and more compact way of passing parameters and data to the procedural is through user data.


  • No labels