Track Points Workflow

The Track Points behavior (located in the Shape Behaviors category) is designed for use with shapes, masks, and paint strokes. The Track points behavior can be used in the following ways:

Note: To apply the analyzed movement of an object to a shape or mask as a whole (not to the shape’s control points), use the Match Move behavior.

For a full description of the Track Points parameters, see Track Points Controls.

Tracking Control Points to a Clip

This section provides a brief overview of using the Track Points behavior to track the vertices of a shape or mask to a clip.

To track a shape or mask using the Track Points behavior
  1. Select the shape or mask you want to track, click the Add Behavior icon in the Toolbar, then choose Shape > Track Points from the pop-up menu.

    The behavior is added to the shape, and trackers appear for each control point on the shape. The trackers are ordered in the same order that the shape was drawn: Control Point 1 is Track 1, Control Point 2 is Track 2, and so on.

    Note: Trackers are not added to disabled shape control points. You can still enable and disable control points once a Track Points behavior is applied to a shape. For more information on working with shape control points, see How to Edit Shapes. For more information on working with masks, see Masking a Layer or Group.

    In this example, the Track Points behavior is applied to a loose mask of seven control points isolating a car in a clip.

    Figure. Canvas window showing several trackers applied to an object.

    Note: Keep in mind that paint strokes usually have a very large number of control points. You should simplify a paint stroke by deleting or disabling control points prior to applying a Track Points behavior to the stroke. To track the stroke as a whole, rather than by its control points, use the Match Move behavior.

  2. Drag the trackers to fine tune their position on the reference patterns.

    As you drag, a magnified view of the area around the tracker appears.

    Figure. Canvas window showing magnified inset that appears when a tracker is dragged.
  3. To disable a tracker, deselect its checkbox in the Behaviors tab of the Inspector.

    Note: Any control points without an associated tracker are not modified.

  4. Click the Analyze button in the HUD or Behaviors tab of the Inspector.

    The mask control points are tracked to the reference patterns.

    In this example, a mask is tracked to a moving car so that the car can be isolated from the rest of the clip. The illustration on the left shows the original unmodified clip. In the illustration on the right, the tracked mask isolates the car, allowing separate effects to be applied to the car and its background even though they are part of the same image. The mask is “protecting” the car from the effects of the heavy blur and desaturation.

    Figure. Canvas window showing a tracked mask.

    Note: As with all behaviors, you can drag or copy (Option-drag) a Track Points behavior to a new shape in the Layers tab. When you apply the behavior to a new shape, the trackers are automatically applied to the control points of the new shape. If the new shape has more control points than the originally tracked shape, only the original track points are applied. For example, if the originally tracked shape has three control points, and the new shape has five controls points, trackers are applied to the first three control points of the new shape. If the new shape has fewer control points than the originally tracked shape, trackers are applied to the existing points on the new shape. For example, if the originally tracked shape has five controls points, and the new shape has three control points, the first three trackers from the original shape are applied to the three control points of the new shape.

Using a Shape Object as the Animation Source

This section provides a brief overview of using the Track Points behavior to apply the animation of a layer (another shape, in this example) to the vertices of a shape or mask. Applying the animation of one animated shape to another is an easy way to quickly create fun, complimentary animations in which the objects appear to “play” with each other.

For this workflow, your project must contain an object that is animated with keyframes or behaviors.

To apply the animation of a shape to the control points of another shape or mask
  1. In a project that contains two shapes, animate one of the shapes using keyframes or a Basic Motion behavior.

    In this example, a simple line shape is animated with the Spin behavior.

    For more information about animating with keyframes, see Animating in the Canvas. For more information about the Basic Motion behaviors, see Basic Motion Behaviors.

  2. Apply the Track Points behavior to a non-animated shape.

    The animated object closest to the object with the applied Track Points behavior in the Layers tab is automatically applied to the Track Points behavior as the animation source, and is displayed in the Source well in the HUD and Inspector.

    In this example, the Track Points behavior is applied to the Bezier shape, and a line used as the source animation is animated with the Spin behavior.

    Figure. Canvas window showing a source object, a Bezier shape with Track Points behavior, and the HUD showing the referenced source object.

    Note: To reference another animated object, drag that object to the Track Points behavior’s Source well or directly to the behavior in the Layers tab.

  3. In the Behaviors tab of the Inspector, choose Attach to Source from the Transform pop-up menu.

    The spinning animation of the line is applied to the Bezier shape. The Bezier shape changes form because the vertex tangents match the transformation of the source animation.

    Figure. Canvas window showing two objects moving in tandem while retaining their original relative positions.
  4. To align the tangents to the transformation of the source object, select the Align Tangents checkbox in the Behaviors tab of the Inspector.

    The spinning animation of the line is applied to the Bezier shape. The tangents remain aligned at their original angles along the shape.

    Figure. Canvas window showing same two objects with Align Tangents checkbox enabled.

    Note: By default, Mimic Source is chosen from the Transform pop-up menu. For more information on the Transform pop-up menu, see Track Points Controls.