Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 218

See also
"Work with the Graph Editor" on page 186
"About animation, keyframes, and expressions" on page 185
About changes in speed
When you animate a property in the Graph Editor, you can view and adjust the rate of change of the property in the
speed graph, or on the motion path in the Composition or Layer panel. As you adjust the rate in one panel, you can
view the changes in the other. In the speed graph, changes in the graph height indicate changes in speed. Level values
indicate constant speed; higher values indicate increased speed.
In the Composition or Layer panel, the spacing between dots in a motion path indicates speed. Each dot represents
a frame, based on the frame rate of the composition. Even spacing indicates a constant speed, and wider spacing
indicates a higher speed. Keyframes using Hold interpolation display no dots because there is no intermediate
transition between keyframe values; the layer simply appears at the next keyframe's position.
A B
A B
Motion path in Composition panel (top) compared to speed graph in Graph Editor (bottom)
A. Dots are close together, indicating lower speed (top); speed is constant (bottom). B. Dots are far apart, indicating greater speed (top); speed
is constant (bottom). C. Inconsistent spacing of dots indicates changing speed (top); speed decreases and then increases (bottom).
The change of speed over time is affected by the following factors:
• The time difference between keyframes in the Timeline panel. The shorter the time interval between keyframes,
the more quickly the layer has to change to reach the next keyframe value. If the interval is longer, the layer changes
more slowly, because it must make the change over a longer period of time. You can adjust the rate of change by
moving keyframes forward or backward along the timeline.
• The difference between the values of adjacent keyframes. A large difference between keyframe values, such as the
difference between 75% and 20% opacity, creates a faster rate of change than a smaller difference, such as the
difference between 30% and 20% opacity. You can adjust the rate of change by increasing or decreasing the value
of a layer property at a keyframe.
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AFTER EFFECTS CS3 212
User Guide