Cryptomatte is an open-sourced standard created at Psyop by Jonah Friedman and Andy Jones. It resolves efficiently the tricky issue of automatically generating consistent ID mattes from renders featuring motion blur, transparency and depth of field.
Cryptomatte reader plugins are freely available for major compositing packages such as Foundry Nuke, Blackmagic Fusion, Adobe Photoshop and more... More information about Cryptomatte is available at GitHub - Cryptomatte.
To output Cryptomatte information in your renders you simply have choose a Layer 3d or a Render Scene and add Cryptomatte to the Sub Pixel Filters attribute.
You don't need to manually set the cryptomatte AOVs using the AOV Editor or AOV Set. This is done automatically.
The Cryptomatte filter has 3 settings:
|Output Material||Export information in a special AOV named
|Output Object||Export information in a special AOV named
|Output Asset||Export information in a special AOV named
Cryptomatte can output scene information as strings in the EXR metadata. This feature is super useful since it allows you to generate masks based on the names of the items. However, this feature comes at a great cost when the scene is complex since the amount of generated data to store that scene information can be extremely high. This leads to huge EXR files that are very slow to open. Since this feature is completely optional, scene information isn't output by default. Only the cryptomatte AOVs are output. To force the output of the scene information, you must set the attributes to
AOVs and Manifest.
It is recommended to set the output the Layer 3d to OpenEXR when saving the layer image