HtoA is a minor feature release adding Python 3 support, using Arnold

Please download the .py3 version of the HtoA installer when installing the Python 3 version of Houdini 18.5.


  1. Download Arnold for Houdini

  2. Follow these installation instructions

System Requirements

  • Houdini, Houdini FX, Houdini Indie and Houdini Education
    • 17.5.460
    • 18.0.597
    • 18.5.596
    • 18.5.633 
    • 18.5.672
  • Windows 10 or later, with the Visual Studio 2019 redistributable.
  • Linux with at least glibc 2.17 and libstdc++ 4.8.5 (gcc 4.8.5). This is equivalent to RHEL/CentOS 7.
  • macOS 10.13 to 10.15. Note that macOS 11 Big Sur is not certified.
  • CPUs need to support the SSE4.1 instruction set.
  • GPU rendering works on Windows and Linux only and requires an NVIDIA GPU of the Ampere, Turing, Volta, Pascal, or Maxwell architecture. We recommend using the 460.39 or higher drivers on Linux and 461.40 (Quadro), 461.40 (GeForce), or higher on Windows. See Getting Started with Arnold GPU for more information.
  • Optix™ denoiser requires an NVidia GPU with CUDA™ Compute Capability 5.0 and above.


  • htoa#1347 Python 3 support 

Bug fixes

  • htoa#1742 Fix the optix_denoiser when denoising AOVs
  • htoa#1740 Fix transmission parameter on the Light LOP 

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