Arnold 7.3 is a significant annual update to Autodesk's renderer, introducing changes that break backward compatibility.

The main change in version 7.3.0 is the support for dithered sampling in progressive and adaptive rendering, resulting in "much more pleasing" noise distribution at low AA sample counts, as shown above. Expanded support for the MaterialX format for rich material and look dev data has been added, allowing rendering of node graphs by blending Arnold nodes with nodes from the standard MaterialX library. Other changes include support for built-in light sources in the Hydra rendering delegate, including support for visibility and matte attributes.

In addition to the listed changes, version 7.3.1 introduces the ability to run the NVIDIA OptiX denoising tool on low-resolution progressive rendering passes, resulting in early scene previews with less noise, as demonstrated above. The Intel Open Image Denoise (OIDN) tool has "10% better performance" on CPU, and now users can choose whether to run OIDN on CPU, GPU, or in automatic mode.
Autodesk has also overhauled GPU rendering, rewriting "most of" the GPU renderer using OptiX 8 - the new version of NVIDIA's GPU ray tracing framework.

The changes introduced in Arnold 7.2.5 improve performance, especially the time to first pixel in the initial renders after updating Arnold, thanks to reduced cold cache pre-warm time. Performance also scales better across multiple GPUs: acceleration when using a second GPU for rendering the standard Robot Soldier test scene increased from 1.1 to 1.7 times. It is also noted that USDZ files can be imported and rendered using the USD procedure.

All Arnold integration plugins have been updated to support the new features. Arnold 7.3.0 and Arnold 7.3.1 are available for Windows 10 and above, RHEL/CentOS 7 and above Linux, and macOS 10.13 and above. Integration plugins are available for 3ds Max, Cinema 4D, Houdini, Katana, and Maya. GPU rendering is supported only on Windows and Linux and requires a compatible Nvidia GPU. The software is available by subscription only, with the cost of a single-user subscription being $50 per month or $400 per year.