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Cryptomatte#

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.

Tip

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.

Important

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:

Attribute Description
Output Material Export information in a special AOV named cryptomatte_material used to identify uniquely each project material. For example, if a material is shared across multiple objects they will share the exact same ID in the AOV.
Output Object Export information in a special AOV named cryptomatte_object used to identify uniquely each single geometry/instance shading group. It is the most granular ID that you can output out of Clarisse as each single geometry's/instance's shading group have a unique ID.
Output Asset Export information in a special AOV named cryptomatte_asset used to identify uniquely each project item. Note that combiners and scatterers will have their own ID. They won't display the ID of the underlying geometry they actually display.

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.

Note

It is recommended to set the output the Layer 3d to OpenEXR when saving the layer image