Adobe After Effects CS4 - Manual (Page 249)

243 USING AFTER EFFECTS CS4
Animation and keyframes
Last updated 12/21/2009
3 Using the Selection tool, click a keyframe and drag the direction handle left or right.
Change speed numerically
You may want to specify speed more precisely than you can by dragging keyframes in the speed graph. In such cases,
specify speed numerically in the Keyframe Velocity dialog box.
The options and units in the dialog box vary depending on the layer property you are editing and may also vary for
plug-ins.
1 Display the speed graph for the keyframe you want to adjust.
2 Select the keyframe you want to edit, and then choose Animation > Keyframe Velocity.
3 Enter values for Speed for Incoming and Outgoing Velocity.
4 Enter a value for Influence to specify the amount of influence toward the previous keyframe (for incoming
interpolation) or the next keyframe (for outgoing interpolation).
5 To create a smooth transition by maintaining equal incoming and outgoing velocities, select Continuous.
Note: By default, the proportions of the current Scale or Mask Feather values are preserved as you edit the values. If you
don’t want to preserve proportions, click the link icon next to the property values in the Timeline panel to remove the icon.
Automatically ease speed
Although you can manually adjust the speed of a keyframe by dragging direction handles, using Easy Ease automates
the work.
After you apply Easy Ease, each keyframe has a speed of 0 with an influence of 33.33% on either side. When you ease
the speed of an object, for example, the object slows down as it approaches a keyframe, and gradually accelerates as it
leaves. You can ease speed when coming into or out of a keyframe, or both.
1 In the Graph Editor or in layer bar mode, select a range of keyframes.
2 Do one of the following:
• Choose Animation > Keyframe Assistant > Easy Ease (to ease speed coming both into and out of selected
keyframes), Easy Ease In (to ease speed coming into selected keyframes), or Easy Ease Out (to ease speed coming
out of selected keyframes).
• Click the Easy Ease , Easy Ease In , or Easy Ease Out button located at the bottom of the Graph Editor.
Smooth motion with roving keyframes
Using roving keyframes, you can easily create smooth movement across several keyframes at once. Roving keyframes
are keyframes that are not linked to a specific time; their speed and timing are determined by adjacent keyframes.
When you change the position of a keyframe adjacent to a roving keyframe in a motion path, the timing of the roving
keyframe may change.
Roving keyframes are available only for spatial layer properties, such as Position, Anchor Point, and effect control
points. In addition, a keyframe can rove only if it is not the first or last keyframe in a layer, because a roving keyframe
must interpolate its speed from the previous and next keyframes.