Download and Installation

Arnold, KtoA, and other downloads are available here. Installation instructions come with KtoA, but can also be viewed here: Installation.


  • Arnold: 5.0.2+
  • Katana: 2.5v6+, 2.6v1+, 3.0v1+
  • Platforms:
    • Linux: x86-64, RHEL 6+ or compatible glibc
    • Windows: 7+ on x86-64, with VC++ 2015 redistributable installed


  • Update Katana version support: Katana version support is updated to 2.6v4 or newer, and initial support for the new Katana 3.0 series. (#278)

  • Custom camera plugins: Custom cameras are now supported, by creating a shader with the arnoldCamera terminal and using the custom camera type as the shader. Note that you must have your camera plugin available via the ARNOLD_PLUGIN_PATH environment variable for it to be recognized. (#63)

  • Per-camera settings: Cameras can now have settings specific to each via the ArnoldCameraSettings node. If this node is not used, then the old camera settings on ArnoldGlobalSettings are used instead as a fallback. It is recommended to set per-camera settings and not rely on the global fallback settings. (#269)

  • Camera exposure: The built-in Arnold control for camera exposure is now available on the ArnoldCameraSettings node. (#272)

  • Resolution ratio controls: In ArnoldGlobalSettings in the camera section there is now an adjustAspect parameter for interpreting the aspect ratio from the image resolution, as well as the pixel aspect ratio from the named resolution in RenderSettings. It defaults to making no adjustments for image aspect, but applies the pixel aspect ratio from RenderSettings chosen resolution. The various choices can choose to adjust for image aspect, and or the RenderSettings resolution's pixel aspect ratio when they are non-square. For all choices except "no adjustments" KtoA will properly embed the pixel aspect ratio into any rendered EXR/TIFF metadata. (#277)

  • Pixel aspect ratio override: There is a new parameter pixel_aspect_ratio on ArnoldGlobalSettings that will override the pixel aspect ratio directly for e.g. anamorphic formats when that isn't set in the resolutions XML file for the given resolution. This aspect ratio is the pixel width divided by the pixel height, and is effectively applied by adjusting the viewable aperture on the camera by Arnold itself. The pixel aspect ratio is embedded as metadata in any rendered TIFF/EXR images. (#277)

  • Color manager: The Arnold global color manager can be created in a Material node with the arnoldColorManager terminal, and then the resulting location set on ArnoldGlobalSettings via the color_manager parameter. By default KtoA provides the OpenColorIO manager, but the SynColor manager can also be used if the plugin from MtoA is included in ARNOLD_PLUGIN_PATH. (#146)

Incompatible Changes

  • Default image aspect adjustment: Previously, the height adjustment due to image resolution was always applied, but didn't take into account the RenderSettings resolution's pixel aspect ratio. This corresponds to the new adjustAspect parameter being set to "adjust height". The new default is "no adjustment, include pixel aspect ratio" instead to accomodate cameras coming from Alembic or USD where they already have the screen window changed to accomodate the image and pixel aspect ratios. When that isn't the case this default may result in a vertical stretching or squashing based on the image resolution defined in the resolution (see the file "$KATANA_ROOT/plugins/Resources/Core/Resolutions/FoundryResolutions.xml" for the built-in resolutions and their pixel aspect ratios). To compensate for this for arbitrary resolutions, you may need to set adjustAspect to one of the adjust width or height options, or alternatively set RenderSettings.adjustScreenWindow to adjust the height or the width. (#277)

Bug Fixes

  • #270 Anamorphic screen windows ignored

  • #276 Light filter references export use the arnoldLight terminal instead of arnoldLightFilter

  • #279 Instanced lights disappear when light linking is used

  • #283 Automatic surface shader connections in gaffer applied inappropriately to child light filters and references

  • #284 Yeti frameRelativeSamples proc parameter has the wrong type

  • #285 Skip arbitrary parameter export if it conflicts with a built-in parameter


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