HtoA 6.3.2.0

22 May 2024

HtoA 6.3.2.0 is minor feature release using Arnold 7.3.2.0.

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

Toon tone-mapping: You can now drive the hue and saturation of tonemapping in the toon shader. The toon shader has four new parameters that complement the existing value-based tonemapping parameters. The connected shader's U coordinate drives direct light hue and the V coordinate drives saturation, which enables textures like those below to map the toon shader's response to colored lighting (Note: make sure to set the image's wrapping mode to clamp and filter to closest for best results) (ARNOLD-10687). These toon parameters include:
No base_tonemap_hue_saturation image -> base_tonemap_hue_saturation image -> specular_tonemap_hue_saturation

Color palette images -> base_tonemap_hue_saturation image.offset_u: 0 to 1 (light color is unchanged)
Better volume denoising: Denoising volumes now produces better results. The changes in how volume albedo is computed help the denoiser to keep more details. Ringing artifacts when objects are viewed against the background are also reduced, and a new N_denoise AOV fixes some denoising artifacts visible in low-AA renders. (ARNOLD-14936, ARNOLD-13071)

7.3.1 7.3.2

7.3.1 7.3.2

7.3.1 7.3.2



No base_tonemap_hue_saturation	image -> base_tonemap_hue_saturation	image -> specular_tonemap_hue_saturation

Many-lights support for light linking: Global light sampling is now applied per group of lights linked to a shape. That can improve rendering performance for scenes with light linking. The ALab scene now renders twice as fast when you use Global Light Sampling. (ARNOLD-14985)
Improved Standard Hair on GPU: The GPU renderer now supports the extra_depth parameter. This enables accurate rendering of blond or bright-colored hair without raising GI_specular_depth.

Improved volume albedo AOV: Volume albedo values are now more physically-based. This improves volume denoising and any LPE AOV using volume albedo is now much more useful for compositing. For backwards compatibility, you can set the new global option legacy_volume_albedo to true. (ARNOLD-13071)
Bake subdivided and displaced geometry: Polygon mesh geometry can be baked with with render-time subdivision and displacement, and saved to USD or ASS. The Arnold ROP has a new Bake Displaced Geometry section, and in Solaris you can use the new Arnold Bake Geometry LOP (HTOA-2598)

Arnold ROP	Solaris

Improved volume albedo AOV: Volume albedo values are now more physically-based. This improves volume denoising and any LPE AOV using volume albedo is now much more useful for compositing. For backwards compatibility, you can set the new global option legacy_volume_albedo to true. (ARNOLD-13071)
Improved OSL interoperability: The color4, color2, vector4, vector2, and matrix33 are now supported as output types of OSL shaders when connected to Arnold shaders. Additionally, Arnold shaders that output RGBA or Vector2 types can now be directly connected to OSL shader color4 and vector2 input parameters. Those features make it easier to mix Arnold and MaterialX standard library shader nodes. (ARNOLD-1398 ARNOLD-14692)
Performance improvements in classic HtoA instancer (HTOA-2574)
Instancer transforms The transform attribute (matrix4 or matrix3) is now supported in the instancer (HTOA-2436)
Update OpenVDB to version 11.0: Arnold now uses the latest OpenVDB library. For the list of changes between OpenVDB version 7.1.1 and version 11.0, see the release notes. (ARNOLD-11217)

Cylinder lights - Cylinder lights are saved as UsdLuxCylinderLight primitives - usd#1894

Geometry baking API: You can now bake subdivided and displaced geometry. You can save the baked geometry either in another universe or you can change the geometry in-place in the same universe. Typically, you would bake geometry by looping over scene nodes with AtNodeIterator. Currently, geometry baking applies to polymesh nodes only. (ARNOLD-2815)
```
 AI_API AtNode* AiNodeGetProcessedGeometry(AtNode* source_node, AtUniverse *dest_universe);
```

Arnold MaterialX Surface Shader nodes have been hidden: To avoid confusion, Arnold versions of the Mtlx Standard Surface nodes have been hidden until arnold-usd#1897 is fixed.
Save usdz files to a usdz_tx folder: Previously when reading a .usdz file, any generated .tx files would be saved to a folder named <usdz_filename>.tmp. The .tmp extension may have led users to remove this folder prematurely, resulting in extra work the next time the usdz was rendered. These files will now be written to and read from a folder name <usdz_filename>.usdz_tx. (ARNOLD-14999)
Improved volume AOV: The volume albedo AOV and LPE scattering event has been improved. For backwards compatibility, you can set the new global option legacy_volume_albedo to true. (ARNOLD-13071)

HTOA-2575 - Fixed some Arnold object nodes (such as Arnold Light) to prevent indirect loading of htoa_ipr and zmq in batch sessions
HTOA-2607 - Fixed 'promoting user parameter "polymesh:smoothing"' warnings when using packed alembic primitives
ARNOLD-8165 - Crash when curvature, ambient occlusion, or round corners is used in displacement
ARNOLD-14551 - Add log notification when FIS is enabled
ARNOLD-14590 - Very bright lights, such as the sun, are not properly occluded by dense volumes
ARNOLD-14970 - [GPU] Rare “stack overflow exception” crash with OSL shaders
ARNOLD-14995 - [GPU] Crash when attempting to render a Bifrost volume
ARNOLD-14998 - Rare crash in Windows when texture_searchpath contains a root directory
ARNOLD-15015 - Profiler data is lost when other universes are destroyed
ARNOLD-15030 - GPU renderer and denoiser imagers incorrectly overriding FIS parameters set in options
ARNOLD-15040 - AiTextureLoad crashes with textures that use subimages as mipmaps
usd#1900 - Fix transform hierarchies for Arnold non-xformable primitives
usd#1903 - USD Writer should skip materials when the shader mask is disabled
usd#1906 - Fix light filters assignment order in the render delegate to make it consistent with the procedural.
usd#1912 - Procedural interactive updates don't consider primitives visibility

Houdini, Houdini FX, Houdini Indie and Houdini Education
- 19.0.720
- 19.5.805
- 20.0.688
Linux with at least glibc 2.28 and libstdc++ 9.3.1 (gcc 9.3.1) for Houdini 19, 19.5, and 20. This is equivalent to RHEL/CentOS 7.
Linux with at least glibc 2.17 and libstdc++ 11.2.1 (gcc 11.2.1) for Houdini 20. This is equivalent to Rocky 8.
macOS 10.13 or later, macOS 11 or later for Houdini 19.5
Apple Mac models with M series chips:
- Natively supported by Arnold for Houdini 19.5
- Supported under Rosetta 2 mode for older versions of Houdini
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 535.104 or higher drivers.
- On Windows, we recommend 537.13 or higher drivers.
Optix™ denoiser requires an NVidia GPU with CUDA™ Compute Capability 5.0 and above.



Color palette images -> base_tonemap_hue_saturation	image.offset_u: 0 to 1 (light color is unchanged)



	7.3.1	7.3.2



	7.3.1	7.3.2



7.3.1	7.3.2