Psyop have announced the beta release of Cryptomatte for Arnold 5, as well as version 1.2.0-Beta of the Cryptomatte specification, and reference Nuke implementation.

Note that this is a beta release, both for AlShaders and Nuke.

Nuke and Fusion: https://github.com/Psyop/Cryptomatte

Arnold 5 Cryptomatte

Cryptomatte for Arnold 5 is being released as part of AlShaders, as before, but is now a standalone node.  Arnold 5.0.1 adds support for “AOV shaders”, which allow code to run on all materials in a scene, without manually connecting passthrough nodes.  This improves the workflow in numerous ways.  Using a central AOV shader node gives easy access to global Cryptomatte settings (on the one central Cryptomatte node).  It is now also much easier for a studio to create a customized version of Cryptomatte, since the code does not need to be embedded in a surface shader.  In addition to adopting the AOV shader methodology, we’ve added other features as well, such as sidecar manifests that work with deferred-loaded stand-ins, and “integer offsets” for modifying names.

Arnold 5 Documentation: Cryptomatte documentation, MtoA, MAXtoA, C4DtoA, HtoA.