Adobe After Effects CS4 - Manual (Page 248)

242 USING AFTER EFFECTS CS4
Animation and keyframes
Last updated 12/21/2009
Dragging direction handle to create a peak
Start or stop change gradually
Direction handles can create gradual starts and stops, such as a boat slowing to a stop and then starting again. When
you use this technique, the speed graph resembles a smooth U shape.
1 In the Timeline panel, expand the outline for the keyframe you want to adjust.
2 Click the Graph Editor button and display the speed graph for the property.
3 Make sure the interpolation method for the keyframe you want to adjust is set to Continuous Bezier or Bezier.
4 At the desired keyframe, drag the direction handle down until it is near the bottom of the graph.
5 Drag the direction handles on either side of the keyframe away from the center of the keyframe.
Dragging the direction handle to make a gradual change
Adjust influence of a direction handle on an adjacent keyframe
Along with controlling the level of acceleration and deceleration, you can also extend the influence of a keyframe
outward or inward in relation to an adjacent keyframe. Influence determines how quickly the speed graph reaches the
value you set at the keyframe, giving you an additional degree of control over the shape of the graph. The direction
handle increases the influence of a keyframe value in relation to the neighboring keyframe when you drag it toward
the neighboring keyframe, and it decreases the influence on the neighboring keyframe when you drag it toward the
center of its own keyframe.
1 In the Timeline panel, expand the outline for the keyframe you want to adjust.
2 Click the Graph Editor button and display the speed graph for the property.