Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 215

Continuous Bezier interpolation
Like Auto Bezier interpolation, Continuous Bezier interpolation creates a smooth rate of change through a keyframe.
However, you set the positions of Continuous Bezier direction handles manually. Adjustments you make change the
shape of the value graph or motion path segments on either side of the keyframe.
If you apply Continuous Bezier interpolation to all keyframes of a property, After Effects adjusts the values at each
keyframe to create smooth transitions. After Effects maintains these smooth transitions as you move a Continuous
Bezier keyframe on either the motion path or the value graph.
Hold interpolation
Hold interpolation is available only as a temporal interpolation method. Use it to change the value of a layer property
over time, but without a gradual transition. This method is useful for strobe effects, or when you want layers to
appear or disappear suddenly.
If you apply Hold temporal interpolation to all keyframes of a layer property, the value of the first keyframe holds
steady until the next keyframe, when the values change immediately. In the value graph, the graph segment following
a Hold keyframe appears as a horizontal straight line.
Even though Hold interpolation is available only as a temporal interpolation method, the keyframes on the motion
path are visible, but they are not connected by layer-position dots. For example, if you animate a layer's Position
property using Hold interpolation, the layer holds at the position value of the previous keyframe until the current-
time indicator reaches the next keyframe, at which point the layer disappears from the old position and appears at
the new position.
You can easily freeze the current frame for the duration of the layer using the Freeze Frame command. To freeze a
frame, position the current time indicator at the frame you want to freeze. Make sure the layer is selected and then
choose Layer > Time > Freeze Frame. Time-remapping is enabled, and a Hold keyframe is placed at the position of
the current time indicator to freeze the frame.
Note: If you previously enabled time-remapping on the layer, any keyframes you created will be deleted when you apply
the Freeze Frame command.
You can use Hold interpolation only for outgoing temporal interpolation (for the frames following a keyframe). If
you create a new keyframe following a Hold keyframe, the new keyframe will use incoming Hold interpolation.
To apply or remove Hold interpolation as outgoing interpolation for a keyframe, select the keyframe in the Timeline
panel, and choose Animation > Toggle Hold Keyframe.
Apply and change interpolation methods
You can apply and change the interpolation method for any keyframe. You can apply changes using the Keyframe
Interpolation dialog box, or you can apply them directly to a keyframe in layer bar mode, in a motion path, or in the
Graph Editor. You can also change the default interpolation After Effects uses for spatial properties.
See also
"Select keyframes" on page 190
"About animation, keyframes, and expressions" on page 185
"Shortcuts for keyframes" on page 643
"Shortcuts for showing properties in the Timeline panel" on page 640
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User Guide