Apple Motion 5.1.1 - Manual (Page 981)

Chapter 22 Motion tracking 981
•
Sharpening or blurring a clip or an object with a filter, exporting the clip, importing the clip
into the same group as the original footage, tracking the filtered clip, then using that tracking
data as the source for other tracking behaviors.
Note: Other filter tricks may be helpful, such as using a filter to isolate a less-noisy color
channel of a clip or an object.
•
Setting the View resolution to a lower setting, which may speed the tracking analysis.
What does not help you
•
Applying any filter to a clip or object before tracking.
•
Soloing or isolating a tracked clip. This does not speed tracking analysis.
•
Adding multiple Stabilize behaviors. This does not help to further stabilize an analyzed clip,
because the tracker analyzes the original source footage and not the analyzed clip (or a
filtered clip).
•
Converting a track to keyframes and stabilizing again.
•
Selecting a tracking reference feature that does not change perspective, scale, or rotation. The
Motion tracker handles changes in perspective, scale, and rotation very well.
Basic strategies to improve tracking results
Selecting a good tracking reference feature in a movie or image sequence is pivotal in achieving
an accurate track. Tracking a single reference pattern with a single analysis pass rarely yields
a perfect result. More often, a successful track combines automatic and manual tracking,
experimenting with parameter settings, and resetting reference points at various locations in
the clip.
Use the following basic techniques to improve your tracking results.
Find a good reference pattern
m Play the footage several times to locate a reference pattern that satisfies as many of the following
rules as possible:
•
Contains perpendicular edges, such as dots, intersections, and corners. Lines and straight
boundaries should be avoided as tracking reference patterns.
•
Is a high-contrast pattern.
•
Contains even changes in brightness or color. An example of an uneven color or brightness
change is a sharp-edged shadow that passes over your reference pattern.
•
Appears in every frame of the clip (does not move offscreen or become obscured by other
objects).
•
Is distinct from other patterns in the same neighborhood in the clip.
Manually modify track points
If you are not satisfied with the location of a track point, you can drag it to adjust its position.
1 Position the playhead at the frame you want to modify.
The track point at the playhead position is highlighted.
2 Do one of the following:
•
Drag the highlighted track point in the Canvas to adjust its position.
•
Drag in the Tracker Preview area in the Behaviors Inspector.
67% resize factor