Motion Tracking Overview (Pro Only); Uses Of Motion Tracking (Pro Only) - Adobe AFTER EFFECTS 7.0 Manual

Chapter 15: Motion tracking (Pro only)

Motion tracking overview (Pro only)

Uses of motion tracking (Pro only)

Using conventional editing techniques, it is difficult and time-consuming to synchronize visual effects or other
images with moving footage. The motion tracking features of After Effects let you easily create composites and
dynamic visual effects regardless of whether the subjects or the camera (or both) are moving. After Effects can follow
or track the movement of a specified area in a shot and then apply that movement to an effect, image, or other
footage. The resulting visual effect precisely matches the original moving footage.
You can track the scale of a feature, view and edit the tracker's motion path, restrict a motion target and the feature
region to horizontal or vertical movement, or make After Effects perform a specified action automatically based on
the tracking accuracy.
Motion tracking has many uses:
•
Combining elements filmed separately, such as adding video footage to the side of a moving city bus or a star to
the end of a sweeping wand.
•
Animating a still image to match the motion of action footage, such as making a cartoon bumblebee pursue a
swaying flower.
•
Adding effects that follow a moving element, such as applying a lens flare to a scene where the camera pans or
making a ball glow.
•
Applying effects or transform properties to a layer using tracking data in expressions, such as stretching a wire coil
between two objects.
•
Stabilizing footage, such as smoothing the wobble of footage shot with a handheld camera.
Depending on the encoder you use, it is possible to decrease the size of your final output file by stabilizing motion
footage. Random motion, such as from the jostling of a handheld camera, can make it difficult for many compression
algorithms to compress your video.
See also
"About expressions" on page 555
About motion tracking (Pro only)
After Effects tracks motion by matching subpixels from a selected area in a frame to subpixels in each succeeding
frame. You specify the area to track by using the track point. The track point contains a feature region, a search region,
and an attach point. After Effects displays the track point during tracking in the Layer panel.
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