About Tracking

The Tracker is a tool for following and capturing the motion of an on-screen feature, and then applying that stored motion to a second element, so that the two appear to be "locked" together.

You can track any number of features in a clip:

• In 1-point tracking, you track a single feature for position.
• In 2-point tracking, you track two features, using the relationship between the two to track scale and/or rotation.
• In 4-point tracking (more commonly referred to as corner pinning), you track four features.
• In multiple-point tracking, you track as many features as you want.

You can apply the stored motion to various elements:

• You can apply the motion to an object. For example, you could track a halo over the head of a person in a clip. Assume that in the clip the person tilts their head and advances toward the camera. You would want the halo to reflect the position, scaling, and rotational changes of the tracked features on the person's head.

Note: When you track scaling with combustion, you are not performing "3D tracking" in true Z-space. You are simply measuring the amount of change over time in the size of the tracked object.

• You can apply the motion to each of the control points of an object. The shape of the object changes to reflect the motion of the reference feature its control points are locked to. For example, if you want to replace the label on an actor's clothing, each corner on the new label would track a corner on the old label. The shape of the new label would change to correspond to those movements.
• You can apply the motion to the center point of a filter. For example, you may want the center point of a lens flare filter to track the motion of a street lamp.
• You can apply the motion to a Stabilize filter, which removes the motion from the clip. In this case, you would track unwanted motion in the clip.

Note that the Tracker is not limited to composites, as there are many useful applications for it in Particles and Paint as well. For example, a nested composite that is complete except for wire removal can have a cloned paint stroke tracked to the wire in Paint.