(from 2022.1 XB2 - 13.04)
The new AOV 'Cryptomatte mask' allows to create a mask image using one of the cryptomatte passes.
-Open the AOV Scene setting
-Click the '+' button to add an AOV output.
-Set the AOV type to 'Cryptomatte mask AOV output'
-Click the 'AOV 1' button to expand the items
-Choose the cryptomatte pass (Material node, etc..)
-Open the octane Viewport
-Click the 'Pick Add' button, and click on the objects you want to include as the mask.
If the selected cryptomatte pass is not currently enabled, a dialog will ask you if you want to enable it.
You will see the 'matte' (Material name or object property corresponding to the crypromatte pass) added in the list box.
While picking with 'Pick Add', you can remove a matte by holding the Shift key and pick.
While picking with 'Pick Remove', you can add a matte by holding the Shift key and pick.
To remove mattes, you can also use the context menu on items of the list box, and select 'remove selected matte(s)', or remove them all with the 'Clear mattes' button.
You can stop picking:
-by pressing the highlighted 'Pick' button again.
-by clicking the the right button mouse
-by pressing the Esc key.
Note that the other picking modes available in the Octane viewport (Focus picker and White balance picker) can also be stopped the same way, and only one picking mode can be used at a time.
Note: If it interferes with you settings, you may disable the usage of Esc key and Right mouse click in Octane Preferences / User interface tab.
