The rigid mask tracker transforms a mask so that it follows the motion of an object (or objects) in a movie.
When a mask is selected, the Tracker panel switches to mask tracking mode, and displays the following controls:
- Controls for tracking forward or backward either one frame at a time or until the end of the layer
- Method, with which you can choose to modify position, scale, rotation, skew, and perspective for the mask
If the Tracker panel is not displayed, select a mask and go to Animation > Track Mask to display the panel. You can also context-click a mask and choose Track Mask from the context menu.
The result of using the mask tracker can be seen in the application of keyframes for the Mask Path property; the mask shape matches the transformations tracked in the layer, depending on the type of method that is chosen.
Note the following points when tracking:
- For effective tracking, the tracked object must maintain the same shape throughout the movie, though the position, scale, and perspective of the tracked object can change.
- You can select multiple masks before beginning the tracking operation, and keyframes are then added to the Mask Path property for each selected mask.
- The layer being tracked must be a track matte, an adjustment layer, or a layer with a source that can contain motion. This includes layers based on video footage and precompositions, but not solid-color layers or still images.
The mask tracking analysis searches for content inside the mask. Use the Mask Expansion property to expand or contract the area of the mask.