Rotobrush applied to a clip of people sitting a room with walls and windows. Walls need color adjustment and, simultaneously, windows need a separate level adjustment.
Rotobrush used to mask either walls or windows works. Color and level effects are made in a lower layer revealed through the masks.
Either mask tracks and works well separately but not simultaneously. One mask layer or the other must be "eye-balled out"--made not visible--for the other to reveal properly.
But how to have both active simultaneously and reveal properly???
In Photoshop independent masks can be grouped and applied as a group. For example, a face might have eyes, cheeks, pupils, etc., all independently masked and adjusted using various blend modes, color adjustments, opacity, etc. Works great!
How to have the same sort of multiple masks work in AE???
Must be something pros do every day.
Nesting? Pre-comp? An alpha mask setting for each layer???