HtoA 6.4.4.0

28 August 2025

HtoA 6.4.4.0 is a minor feature release using Arnold 7.4.3.1. It is the first HtoA release supporting Houdini 21.

Installation

• Download Arnold for Houdini from your Autodesk Account. See Download Arnold for more information about downloading HtoA from your Autodesk Account.

• Follow these installation instructions

Enhancements

• Support multiple AOVs with the same name: When rendering with hydra render products with husk, it is now possible to output the same AOV multiple times usd#2391

• MeshLightAPI schema: MeshLight API schemas are now supported in Hydra and USD usd#2390

• RenderPass primitives: Render Pass primitives are now supported when authored in USD files usd#2407

Bug Fixes

• HTOA-2955 - Fix Solaris viewport compositing by correctly setting depthstyle to linear
• HTOA-2994 - Fix deform_keys/transform_keys parameter warnings on the Alembic Object node
• usd#2391 Remove warnings when rendering with an Arnold camera

Known Issues

• HTOA-2999 Changing per-instance cryptomattes with point instancers

System Requirements

• Houdini, Houdini FX, Houdini Indie and Houdini Education

  • 20.0.896
  • 20.5.684
  • 21.0.440

• Linux with at least glibc 2.17 and libstdc++ 11.2.1 (gcc 11.2.1) for Houdini 20/20.5. This is equivalent to Rocky 8.

• macOS 11 or later

• Apple Mac models with M series chips are natively supported by HtoA

• x86-64 CPUs need to support the SSE4.1 instruction set. Apple Mac models with M series chip are supported natively mode.

• GPU rendering works on Windows and Linux only and requires an NVIDIA GPU with the Maxwell architecture or later.

  • On Linux, we recommend 570.153.02 or higher drivers.
  • On Windows, we recommend 573.42 or higher drivers.

• Optix™ denoiser requires an NVidia GPU with CUDA™ Compute Capability 5.0 and above.

• Intel OIDN GPU support is limited to:

  • MacOS
    • Apple native CPUs (M1 and newer)
  • Windows
    • Intel Xe dedicated and integrated GPUs
    • NVIDIA GPUs using Turing or newer architectures