Adobe After Effects CS3 - Manual (Page 220)

AFTER EFFECTS CS3
User Guide
215
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.