HtoA 6.4.5.2 - Arnold for Houdini

17 December 2025

HtoA 6.4.5.2 is a bugfix release using Arnold 7.4.4.1. For the full list of features in HtoA 6.4.5.0, see the HtoA 6.4.5.0 release notes.

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

Bug Fixes

• HTOA-1078 - Arnold ROP reads VDB files when exporting ass files
• HTOA-2938 - Imagers are recreated on every parm change in classic HtoA
• HTOA-3023 - Loading an Arnold ROP scene crashes Houdini
• HTOA-3027 - transform_keys is missing from render geometry settings LOP
• HTOA-3049 - Camera motion blur can randomly disappear
• HTOA-3085 - Unexpected motion blur when both camera and shape are moving with same speed
• HTOA-3050 - Bake Geometry LOP fails without a camera
• HTOA-3052 - Update TX Textures can fail or crash
• HTOA-3092 - Fixed gcc11 suffix in Houdini 21 package
• HTOA-3084 - AutoTX re-generates TX files created by Update TX Textures
• HTOA-3097 - Houdini 21 recipes do not work in Arnold Material Builder
• HTOA-3110 - Solaris renders trigger GL display
• ARNOLD-16840 - Fixed custom AOV settings resetting when in interactive mode.
• ARNOLD-17049 - Fixed bloom rotation in aperture mode for angles below -180°
• ARNOLD-17058 - [GPU] Fixed incorrect per-depth ray counts reported in stats.
• ARNOLD-17076 - Fixed random missing lights when using light_group and shadow_group on ginstance.
• ARNOLD-17088 - Fixed random crash when using curves and points nodes with min_pixel_width.
• ARNOLD-17140 - Faster procedural node destruction when most of its nodes are modified. Fixes very slow instancer destruction.
• ARNOLD-17149 - [GPU] Fixed small per-instance GPU memory leak.
• ARNOLD-17151 - Fixed an incorrect "Rendering CPU utilization was only 0%" message being reported when utilization was greater than 0%.
• ARNOLD-17171 - Fixed AiTextureTxFileNeedsUpdate returning false when colorconvert arguments contain empty spaces.
• usd#2467 - Hidden primitives do not show up when turned visible
• usd#2472 - Regression in render settings default value for autoTX
• usd#2478 - Support the Z AOV for the Hydra depth buffer

System Requirements

• Houdini, Houdini FX, Houdini Indie and Houdini Education

  • 20.0.896
  • 20.5.684
  • 21.0.512

• 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 580.95.05 or higher drivers.
  • On Windows, we recommend 581.42 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)
  • Linux
    • NVIDIA GPUs using Turing or newer architectures
  • Windows
    • Intel Xe dedicated and integrated GPUs
    • NVIDIA GPUs using Turing or newer architectures
    • AMD GPUs with RDNA2 (Navi 21 only) and RDNA3 (Navi 3x) architectures