7.3.0.0

27 March 2024

Arnold 7.3.0.0 is a feature release bringing progressive dithered sampling support, more accurate light group AOVs, improved MaterialX support, compatibility with USD 23.11, BSDF API improvements for shader writers, as well as multiple optimizations and bugfixes.

Enhancements

• Progressive dithered sampling: Arnold now supports dithered samples in progressive and adaptive rendering. Dithering brings nicer noise distributions at low AA sample counts. (ARNOLD-10739)

before 7.3.0.0, AA=1	7.3.0.0, AA=1

• Improved MaterialX support: Arnold can now render MaterialX node graphs mixing Arnold nodes with MaterialX standard library nodes. DCCs loading the Arnold node definitions benefit from the newly added UI metadata and provide a better user experience. Arnold also now uses MaterialX 1.38.8, this update brings new nodes in the MaterialX standard library, for a full list of changes please see the full release notes. (ARNOLD-14286, ARNOLD-14623, ARNOLD-14513)

• Emission and per-light-group AOVs: Per-light-group indirect AOVs no longer include emission. Emissive surfaces now only appear in the "default" light group output. When using emission in shaders, the sum of the light group AOVs will now add up to the beauty pass. (ARNOLD-9453)

• Evaluate autobump in SSS on GPU: Autobump will now be evaluated in the SSS computation with the GPU renderer when the sss_use_autobump option is enabled, this matches the behavior when rendering on CPU. (ARNOLD-8494)

• Device selection in the Intel Denoiser: It is now possible to toggle between Auto/CPU/GPU for OIDN denoiser imager. Arnold now also provides accurate timing information for the denoiser in the log. (ARNOLD-14524, ARNOLD-14526)

• Batch renders now abort on license fail: Arnold now aborts if there is a license error in a batch render. The option abort_on_license_fail is now true by default, and applies to batch renders only. This means you don't have to check rendered image sequences for watermarks. Interactive renders do not abort, and have a watermark on license fail as usual. The environment variable ARNOLD_FORCE_ABORT_ON_LICENSE_FAILoverrides this default behavior (0 = batch and interactive render with watermarks on license fail, 1 = batch and interactive abort on license fail). (ARNOLD-13024)

• Add license checkout time to render statistics: The render statistics now include the "license checkout time", which is the time in microseconds spent on license checkout for a specific render. This is useful to users to diagnose long checkout times when rendering in batch. (ARNOLD-13497)

• New network server configuration modes in the License Manager: You can now choose a license file or specify a three server redundancy setup on the network server configuration tab in the License Manager. (ARNOLD-14586, ARNOLD-14615)

• Upgrade to OpenColorIO 2.3.2: OpenColorIO library has been upgraded to use version 2.3.2. For the list of changes see the release notes for 2.3, 2.3.1, and 2.3.2. (ARNOLD-14026)

• Updated Alembic to 1.8.5: The Alembic procedural has been upgraded to use version 1.8.5 of the Alembic library. (ARNOLD-14448)

• Autodesk Analytics Program: A newer version of the Autodesk Analytics Program (ADP) has been integrated into Arnold. This brings stability improvements. (ARNOLD-13805)

USD Enhancements

• Update to USD 23.11: The USD version was updated from 22.11 to 23.11 in the procedural. The USD Arnold procedural embeds a static version of USD 23.11, see USD 23.11 Changelog for all the changes related to this new version of USD.
• Light instances: You can now instance lights with a Point Instancer. (usd#1705)
• Visibility and Mattes on instances in Hydra: In the Hydra Render Delegate, the Arnold visibility and matte attributes now work on instances. (usd#1635)

API changes

• Builtin metadata: Nodes and their parameter definitions have been augmented with more metadata that could be useful across DCCs. The metadata that has been included are the following: animateable, default, help, gpu_support, hide, linkable, max/min, softmax/softmin and units. Some of these metadata were previously distributed as separate mtd files in each DCC. (ARNOLD-10265)

• Remove _private functions from BSDF API: The functions AiMicrofacetBSDF_private and AiMicrofacetRefractionBSDF_private (included to support dielectric priority) have now been removed from the BSDF API. The functions AiMicrofacetBSDF and AiMicrofacetRefractionBSDF now take dielectric_priority as an optional argument. (ARNOLD-14166)

• Expose conductor Fresnel mode as an enum in AiMetalBSDF: AiMetalBSDF has been modified to accept an AtMetalFresnelMode enum argument, selecting between the original "Gulbrandsen" conductor Fresnel model and the new "F82-tint" model. (ARNOLD-14165)

• Expose random walk version in the closure API: AiClosureRandomWalkV2BSSRDF has been removed, and instead the existing AiClosureRandomWalkBSSRDF has been modified to accept an AtRandomWalkVersion enum argument, selecting between the original v1 and v2 SSS modes. (ARNOLD-14164)

• Expose thin walled transmission in the public BSDF API: AiMicrofacetBSDF has been modified to accept an optional thin_walled_transmission argument, which specifies the fraction of the BSDF considered to represent a thin-walled dielectric. This is used to implement thin-walled transmission in Standard Surfaces. This was previously implemented in a way that circumvented the API, which has been fixed to be more explicit with this change. (ARNOLD-14167)

• Provide azimuthal roughness to AidEonBSDF: AidEonBSDF has been modified to accept a roughness_azimuthal argument, specifying the specular roughness for azimuthal scattering specifically. This is in addition to the existing roughness argument specifying the specular roughness for longitudinal scattering. (ARNOLD-8325)

• Removed AiADPSetIntroShown() and AiADPDialogStrings(): These deprecated functions were removed from the Arnold API. (ARNOLD-13805)

• Change AiUniverseCacheFlush API to receive a non-const universe: The AtUniverse passed into AiUniverseCacheFlush() was changed from const to non-const. (ARNOLD-14548)

• Remove deprecated AiGPUCachePopulate functions: Deprecated functions AiGPUCachePopulate(), AiGPUCachePopulateStatus(), AiGPUCachePopulateRemainingSeconds(), and AiGPUCachePopulateTerminate() have been removed. (ARNOLD-14570)

• Remove deprecated AiRenderSetCallback function: Deprecated function AiRenderSetCallback() has been removed. (ARNOLD-12583)

Incompatible Changes

• This version breaks binary compatibility: Shaders, procedurals, and other plugins compiled against older versions of Arnold are not compatible with this version of Arnold and need to be updated and recompiled.

• Autodesk Network Licensing version: Arnold 7.3 switches to ARNOL_2025 licensing. (ARNOLD-14292)

  • Single-user subscriptions will work with Arnold 7.3. The plugin installers automatically register the new version. If you do not use a plugin, then after you download Arnold, open the Arnold License Manager and click Register.
  • Existing network licenses will not work with Arnold 7.3. Log on to your Autodesk account to generate your new ARNOL_2025 licenses.
  • If you do not run the installers, and you manually register Arnold, then use--pk C0PQ1 --pv 2025.0.0.F with the AdskLicensingInstHelper command.

• abort_on_license_fail defaults to true: Arnold now aborts by default if there is a license error in batch renders. You can revert to the previous behavior by setting the abort_on_license_failto false, or by using the new ARNOLD_FORCE_ABORT_ON_LICENSE_FAIL environment variable. (ARNOLD-10455, ARNOLD-13024)

• Emission and per-light-group AOVs: Per-light-group indirect AOVs no longer include emission. (ARNOLD-9453)

Bug Fixes

• ARNOLD-14246 - [MaterialX] Promoted attributes and nodegraph interfaces are ignored
• ARNOLD-14601 - [MaterialX] Missing enum values in node definitions
• ARNOLD-14612 - [MaterialX] Ignored color space on standard library image nodes
• ARNOLD-14646 - [MaterialX] Crash when using the distance node in USD
• ARNOLD-14561 - [MaterialX] Crash when mixing Arnold and standard library shaders
• ARNOLD-14287 - Rare crash when compiling OSL with LLVM during IPR
• ARNOLD-14634 - Error when denoising unsupported pixel type AOVs in OIDN and OptiX
• usd#1758 - Fix several crashes by returning a default value when an attribute type is not recognized.
• usd#1756 - Registry should declare filenames as assets in GetTypeAsSdfType.
• usd#1770 - Fix exr driver always rendering float with husk when productType is arnold.
• usd#1772 - RectLight texture uvs are now consistent between husk, kick and other renderer.
• usd#1776 - Fix incorrect PointInstancer instance orientations in the render delegate.
• usd#1769 - Fix curve uvs when they are vertex interpolated.
• usd#1784 - The aov layer name is now correctly taken into account when rendering exrs with husk and using the arnold productType.

System Requirements

• 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 11 or later.
• x86-64 CPUs need to support the SSE4.1 instruction set. Apple Mac models with M series chips are natively supported.
• GPU rendering and OptiX denoising work on Windows and Linux only and require 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.