Apple Motion 5.1.1 - Manual (Page 955)

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Motion tracking overview
Motion tracking is a method of recording the movement of an element (a shape or reference
point in a movie clip) in the Canvas, then applying that recorded movement data to another
element in the Canvas.
Motion provides a set of automated tracking behaviors that allow you to do the following:
•
Match move elements in movie clips: You can apply tracking data from a background element
(such as a billboard) to a composited foreground element (such as a graphic of a logo) so both
elements appear to be locked together. This technique is known as match moving.
•
Match move animated objects in the Canvas: You can apply the motion data of an animated
object to another object in the project. For example, you can attach a smoke particle emitter
to an animated spaceship so a rocket exhaust trail follows wherever the spaceship moves.
•
Stabilize camera movement in movie clips: You can apply tracking data to remove unwanted
camera movement or jitter in a movie or image sequence. For example, you can smooth
handheld camera shots.
•
Unstabilize movie clips: You can restore movement to a previously stabilized movie. This
technique is useful when you stabilize a clip to add a foreground effect but want to restore the
original camera movement to the final composite.
•
Track the position parameter of a filter: You can apply tracking data to the position parameter
of a filter. For example, you can make the center point of a Light Rays filter follow a moving
flashlight beam in a movie clip. The tracking data from the flashlight beam is applied to a
single parameter of the filter (the Center parameter), rather than to the filter as a whole.
•
Track the control points of a shape or mask: You can apply tracking data from reference points in
a movie clip to the control points of a shape or mask. For example, you can use this technique
to attach a mask to a moving element in a movie clip, isolating that element to apply
additional effects to it.
Motion lets you track one or multiple reference features in a clip:
•
One-point tracking: Track a single reference pattern (a small area of pixels) in a movie clip to
record position data.
•
Two-point tracking: Track two reference patterns in a movie clip and use the relationship
between the tracked points to record position, scale, and rotation data.
•
Four-point tracking: Often referred to as four-corner pinning. Track four reference patterns
in a movie clip to record position, scale, and rotation data. The four trackers analyze the
relationship between four reference patterns, such as the corners of a picture frame or
television monitor. This data is applied to each corner of an image or clip to “pin” the clip so it
appears locked in the picture frame or television monitor.
Motion tracking
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