HtoA 6.4.4.0 - Arnold for Houdini
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
- MacOS