Adobe 65008009 - After Effects CS4 Using Manual page 240

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Last updated 12/21/2009 USING AFTER EFFECTS CS4
Animation and keyframes
No interpolation
No interpolation is the state in which a layer property has no keyframes—when the stopwatch is turned off and the I-
beam icon appears in the Timeline panel under the current-time indicator. In this state, when you set the value of a
layer property, it maintains that value for the duration of the layer, unless overridden by an expression. By default, no
interpolation is applied to a layer property. If any keyframes are present for a layer property, some type of interpolation
is in use.
Linear interpolation
Linear interpolation creates a uniform rate of change between keyframes, which can add a mechanical look to
animations. After Effects interpolates the values between two adjacent keyframes as directly as possible without
accounting for the values of other keyframes.
If you apply Linear interpolation to all keyframes of a temporal layer property, change begins instantly at the first
keyframe and continues to the next keyframe at a constant speed. At the second keyframe, the rate of change switches
immediately to the rate between it and the third keyframe. When the layer reaches the final keyframe value, change
stops instantly. In the value graph, the segment connecting two keyframes with Linear interpolation appears as a
straight line.
Bezier interpolation
Bezier interpolation provides the most precise control because you manually adjust the shape of the value graph or
motion path segments on either side of the keyframe. Unlike Auto Bezier or Continuous Bezier, the two direction
handles on a Bezier keyframe operate independently in both the value graph and motion path.
If you apply Bezier interpolation to all keyframes of a layer property, After Effects creates a smooth transition between
keyframes. The initial position of the direction handles is calculated using the same method used in Auto Bezier
interpolation. After Effects maintains existing direction handle positions as you change a Bezier keyframe value.
Unlike other interpolation methods, Bezier interpolation lets you create any combination of curves and straight lines
along the motion path. Because the two Bezier direction handles operate independently, a curving motion path can
suddenly turn into a sharp corner at a Bezier keyframe. Bezier spatial interpolation is ideal for drawing a motion path
that follows a complex shape, such as a map route or the outline of a logo.
Existing direction handle positions persist as you move a motion-path keyframe. The temporal interpolation applied
at each keyframe controls the speed of motion along the path.
Auto Bezier interpolation
Auto Bezier interpolation creates a smooth rate of change through a keyframe. You may use Auto Bezier spatial
interpolation to create the path of a car turning on a curving road.
As you change an Auto Bezier keyframe value, the positions of Auto Bezier direction handles change automatically
to maintain a smooth transition between keyframes. The automatic adjustments change the shape of the value graph
or motion path segments on either side of the keyframe. If the previous and next keyframes also use Auto Bezier
interpolation, the shape of the segments on the far side of the previous or next keyframes also changes. If you adjust
an Auto Bezier direction handle manually, you convert it to a Continuous Bezier keyframe .
Auto Bezier is the default spatial interpolation.
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.