HtoA 6.4.5.2 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 .
HtoA is not available for the current Houdini production build 21.0.559 because of a bug introduced in 21.0.548 that would cause render delegates to be created twice in rapid succession.
Installation
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 visibleusd#2472 - Regression in render settings default value for autoTXusd#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.
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