Track a shape over a clip

A shape in Refine mask adds to, subtracts from or intersects the AI matte. Tracking moves the shape with the footage so you key it on a few frames instead of every one. Tracking runs on your Mac.

Draw the shape

1. Press P for the Pen, or click + at the top of the Layers list.
2. Click on the picture to add points. Drag while clicking to pull out curve handles.
3. Click the first point to close the shape. A shape needs at least 3 points. The tool bar hint reads Click the first point to close once you have three.
4. In the inspector, set Blend to Add, Subtract or Intersect, and set Feather in pixels. A negative feather softens inward.

The shape appears in the Layers list and gets its own lane in the dope sheet, with a key on the current frame.

To add a point to a finished shape, click on one of its segments with the Pen. ⌥-click a point to toggle it between corner and smooth.

Key it

1. Move to another frame with ← and →, or click in the dope sheet.
2. Press V and drag the points into place. With Auto on, this adds a key on this frame.
3. Press K to set a key without moving anything, or ⇧K to set one halfway between the keys either side.

With keys selected in the dope sheet, the transport offers Hold, Linear and Smooth interpolation and a delete button.

Track it

1. Select the shape and put the playhead on a frame where the shape fits. That frame becomes the track’s reference.

2. In the inspector’s Track section, choose a tracker:

   Tracker	Follows
   AI mask	The AI matte
   Planar	A flat surface’s perspective, such as a screen, a sign or a wall
   Points	Each point on its own

3. Click Track to track the whole clip. ◀ To previous key and To next key ▶ track only as far as the neighbouring key. The tool bar’s Track button also tracks the whole clip.

4. Watch the progress bar in the Track section. Stop cancels the pass and lands nothing.

When the pass lands, the toast names the shape and the frames it covers. A track lane, for example Track · Planar, appears under the shape’s lane in the dope sheet. The Track section shows the range and the reference frame, such as f12–f96 · reference f40.

Extend or correct a track

• Click ◀ To previous key or To next key ▶ again to extend the tracked range.
• Drag the start or end handle on the track lane to change the range, or drag the reference marker to track from a different frame. Each drag re-runs the track.
• Keys still work on a tracked shape. Fix a frame where the track slips by moving points there.
• Remove track removes the track. The keys stay where they show.

Result

The shape follows the subject when you play with Space or step with ← and →. Its track lane spans the frames you tracked, and the inspector’s Track section shows the range and reference frame.

If it doesn’t work

Symptom	Cause	Fix
Select a shape to track	No layer is selected	Click the shape in the Layers list or on the picture
That layer is locked	The shape is locked in the Layers list	Click the lock on its row
Lost the subject at f plus a frame, in the Track section	The tracker could not follow past that frame	Key the shape there and track again, or try another tracker
Remove the points track to add or delete points	A Points track holds a fixed number of points	Click Remove track, edit the points, then track again
The tracker options are greyed out	A pass is running	Click Stop first