Download and Installation

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


  • Arnold: 4.2.15+
  • Katana: 2.1v5+, 2.5v4+
  • Platforms:
    • Linux: x86-64, RHEL 6+ or compatible glibc
    • Windows: 7+ on x86-64, with VC++ 2015 redistributable installed


  • Updated to Arnold KtoA is now updated to and requires Arnold, primarily for implicit surfaces via volume plugins. (#116)

  • Light portals: By using quad light in windows or other openings and turning on the portal parameter, they will become portal lights for any skydome lights present. This is particularly useful for interiors where you wish to light them with a skydome, but would otherwise generate a lot of lighting noise. (#122)

  • ArnoldOpenVDBSurface node: Creation of implicit surfaces from OpenVDB levelset grids is now supported. It uses the same OpenVDB volume plugin for density grids, but emits an implicit node in Arnold rather than a volume node. (#116)

  • Instancing improvements: The ArnoldInstanceSettings node will now copy bounds from the instance source if present and not already set on the instance location itself. It also will verify that instance sources have the correct location type (instance source) and will emit a scenegraph error if that is not the case. (#115)

Incompatible Changes

  • Subdivision defaults: Subdivision type has been changed to none and subdivision iterations has changed to one (instead of zero) to match Arnold core. This should only affect newly-created ArnoldObjectSettings nodes, however. (#114)

  • Instance visibility and sidedness: Whenever an ArnoldGlobalSettings node was used on an instance location it would inappropriately override visibility and sidedness settings. These can still be overridden, but to do so the appropriate mask parameters must be explicitly set (use local value). When not set, the individual settings coming from each source to be instanced will be used. (#119)
  • Autobump visibility defaults and overrides: The ArnoldGlobalSettings node didn't apply autobump visibility correctly in all cases, and didn't allow overriding of individual parameters with a later ArnoldGlobalSettings either. Now it should honor the default (for faster renders, ignoring autobump in diffuse and glossy indirect) and allow predictable overrides. Some scenes may drop autobump in tight glossy reflections, however, so be aware that turning autobump on explicitly for glossy rays may be required to fix those scenes. (#120)

Bug Fixes

  • #114 Improve defaults for subdivision to match Arnold core

  • #119 Instance visibility and sidedness inappropriately overridden in ArnoldObjectSettings

  • #120 Autobump visibility mask by default may not match the core

  • #121 Work around old cryptomatte AOV format requirements


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