Ass File Generation

Arnold Scene Source (.ass) is the native scene definition format, stored in human-readable, editable ASCII files.


KtoA lets you save scenes to .ass files that can later be rendered outside of Katana with kick (a multi-platform, command-line utility) or used for rendering via procedurals.


You can specify which of the following types of nodes are included in the .ass export:

  • All: every node type, including filters, drivers, and so on
  • Geometry: only shape nodes such as polymesh, curves, points, etc
  • Geometry and materials: shape nodes together with shader nodes


Exported .ass files will have binary encoding activated, which will make large arrays of integer and float data have b85 encoding and take up less space on disk.  Although the .ass file itself will still be human-readable and editable, the larger arrays of data will not be.


When exporting to .ass, expand locations of type renderer procedural to get their contents (and the source locations will not be present in the .ass file).

Disable Features

These switches allow you to disable a number of important rendering features. By selectively disabling some features, you can get a feel for where the renderer is spending most of the time, which helps optimizing scenes. This is also useful for isolating errors and artifacts when debugging. Note that not all of these options are interactive - some of them may require the entire scene to be refreshed or exported.

Ignore Textures

Ignore all textures when rendering.

Ignore Shaders

Ignore all shaders when rendering, Arnold will render with a simple n_dot_eye shader instead.

Ignore Atmosphere

Ignore atmospheric shaders. 

Ignore Lights

Ignore all light sources.

Ignore Shadows

Don't perform shadow calculations.

Ignore Subdivision

No objects will be subdivided. This parameter is not interactive.

Ignore Displacement

Displacements will be ignored. This parameter is not interactive.

Ignore Bump

Ignore bump mapping.

Ignore Normal Smoothing

Polygon normals will not be smoothed, resulting in a faceted appearance. This parameter is not interactive.

Ignore Motion

Ignores all motion keys.

Ignore Depth of Field

Ignore depth of field computation.

Ignore Sub-Surface Scattering

Ignore subsurface scattering.

Ignore Operators 

Ignore operators.

Ignore List

Nodes in this list are ignored. For example, the following would skip creation of Lambert, Standard Surface and curves shaders:

ignore_list 3 1 STRING lambert standard_surface curves

Shader Override

Global shader override which allows you to override the shader for all objects in the scene.

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