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AFTER EFFECTS CS3 210 User Guide Modifying a Bezier direction handle See also “Work with the Graph Editor” on page 184 “About animation, keyframes, and expressions” on page 183
Speed graph controls A. Value at the current-time indicator B. Speed graph C. Direction handle (controls speed) See also “Work with the Graph Editor” on page 184 “About animation, keyframes, and expressions” on page 183
A B C Motion path in Composition panel (top) compared to speed graph in Graph Editor (bottom) A. Dots are close together, indicating lower speed (top); speed is constant (bottom). B. Dots are far apart, indicating greater speed (top); speed is constant (bottom). C. Inconsistent spacing of dots indicates changing speed (top); speed decreases and then increases (bottom).
Linear interpolation (top) causes sharp changes; Bezier interpolation (bottom) creates smoother changes.
See also “Work with the Graph Editor” on page 184 “About animation, keyframes, and expressions” on page 183 Control speed between keyframes
• In the Composition or Layer panel, adjust the spatial distance between two keyframes on the motion path.
Increase speed by moving one keyframe position farther away from the other, or decrease speed by moving one keyframe position closer to the other.
More spatial distance between keyframes increases layer speed.
Shorter temporal distance between keyframes increases layer speed.
• Apply the Easy Ease keyframe assistant, which automatically adjusts the speed of change as motion advances toward and retreats from a keyframe.
See also “Work with the Graph Editor” on page 184 “About animation, keyframes, and expressions” on page 183 Work with the speed graph After you have set the shape of a motion path or created keyframes for a property, you can adjust the speed. Using the speed graph, you can adjust the rate of change of a value.
For example, you can change the motion of a layer so that it slows just before a keyframe and then speeds up just after the keyframe, or so that it moves quickly over a certain distance and then slows down smoothly. By adjusting the rise and fall of the speed graph, you can control how fast or slow a value changes from keyframe to keyframe.
Note: Like the value graph, the speed graph displays x, y, and z (3D only) values in different colors: x values are red, y values are green, and z values are blue.
You can control the values approaching and leaving a keyframe together, or you can control each value separately.
The incoming handle increases the speed or velocity when you drag it up, and decreases the speed or velocity when you drag it down. The outgoing handle influences the next keyframe in the same way. You can also control the influence on speed by dragging the handles left or right.
A B C Direction handles in speed graphs A. Incoming direction handle B. Speed control C. Outgoing direction handle
See also “Work with the Graph Editor” on page 184 “Modify Bezier direction handles” on page 209 Adjust the rate of change with the speed graph 1 In the Timeline panel, expand the outline for the keyframe you want to adjust.
2 Click the Graph Editor button and select Edit Speed Graph from the Graph Options menu.
3 Using the Selection tool, click the keyframe you want to adjust.
4 (Optional) Do one of the following:
• To split the incoming and outgoing direction handles, Alt-drag (Windows) or Option-drag (Mac OS) a direction handle.
• To join the direction handles, Alt-drag (Windows) or Option-drag (Mac OS) a split direction handle up or down until it meets the other handle.
5 Do any of the following:
• Drag a keyframe with joined direction handles up to accelerate or down to decelerate entering and leaving the keyframe.
• Drag a split direction handle up to accelerate or down to decelerate the speed entering or leaving a keyframe.
• To increase the influence of the keyframe, drag the direction handle away from the center of the keyframe. To decrease the influence, drag the direction handle toward the center of the keyframe.
Note: When you drag a direction handle beyond the top or bottom of the Graph Editor with Auto Zoom Graph Height on, After Effects calculates a new minimum or maximum value based on how far you dragged outside the graph, and it redraws the graph so that all the values you specify for that layer property are visible in the graph by default.
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
2 Click the Graph Editor button and display the speed graph for the property.
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.
See also “Work with the Graph Editor” on page 184 “About animation, keyframes, and expressions” on page 183
The original motion path (top) shows different velocities between keyframes. After the keyframes are set to rove (bottom), the motion path shows consistent speed over the range of keyframes.
1 In layer bar mode or in the Graph Editor, set up the keyframes for the motion you want to smooth.
2 Determine the beginning and ending keyframes for the range you want to smooth.
3 Do one of the following:
• For every keyframe in the range (except the beginning and ending keyframes), select Rove Across Time in the keyframe menu.
• Select the keyframes you want to rove and choose Animation Keyframe Interpolation. Then choose Rove Across Time from the Roving menu.
The intermediate keyframes adjust their positions on the timeline to smooth the speed curve between the beginning and ending keyframes.
Revert to a nonroving keyframe
• Select the roving keyframe option from the keyframe menu, or drag the roving keyframe left or right.
• Select the keyframes you want to change, and choose Animation Keyframe Interpolation. Then choose Lock To Time from the Roving menu.
Use Exponential Scale You can simulate a realistic acceleration of a zoom lens when working with 2D layers by using Exponential Scale, which converts linear scaling of a layer to exponential scaling. This is useful for creating a cosmic zoom, for example.
Zooming optically with a lens is not linear—the rate of change of scaling increases as you zoom. To simulate this acceleration, Exponential Scale converts the velocity of the scaling to an exponential curve.
1 In layer bar mode or in the Graph Editor, hold down the Shift key and select starting and ending keyframes for the scale property.
2 Choose Animation Keyframe Assistant Exponential Scale.
Note: Exponential Scale replaces any existing keyframes between the selected starting and ending keyframes.
Time-stretching and time-remapping Time-stretch a layer Speeding up or slowing down a layer is known as time-stretching. When you time-stretch a layer, the audio or the original frames in the footage (and all keyframes that belong to the layer) are redistributed along the new duration.
Use this command only when you want the layer and all layer keyframes to change to the new duration.
If you time-stretch a layer so that the resulting frame rate is significantly different from the original frame rate, the quality of motion within the layer may suffer. For best results when time-remapping a layer, use the Timewarp effect.
See also “Apply frame blending to a layer” on page 225 “Timewarp effect” on page 535 Time-stretch a layer from a specific time 1 In the Timeline or Composition panel, select the layer.
2 Choose Layer Time Time Stretch.
3 Type a new duration for the layer, or type a Stretch Factor.
4 To specify the point in time from which the layer will be time-stretched, click one of the Hold In Place options, and then click OK.
Layer In-point Holds the layer’s current starting time, and time-stretches the layer by moving the Out point.
Current Frame Holds the layer at the position of the current-time indicator (also the frame displayed in the Composition panel), and time-stretches the layer by moving the In and Out points.
Layer Out-point Holds the layer’s current ending time and time-stretches the layer by moving the In point.
Time-stretch a layer to a specific time 1 In the Timeline panel, move the current-time indicator to the frame where you want the layer to begin or end.
2 Display the In and Out columns by choosing Columns In and Columns Out from the Timeline panel menu.
3 Do one of the following:
• To stretch the In point to the current time, press Ctrl (Windows) or Command (Mac OS) as you click the In time for the layer in the In column.
• To stretch the Out point to the current time, press Ctrl (Windows) or Command (Mac OS) as you click the Out time for the layer in the Out column.
Reverse a layer’s playback direction When you reverse a layer’s playback direction, all keyframes for all properties on the selected layer also reverse order.
The layer itself maintains its original In and Out points relative to the composition.
Note: For best results, precompose the layer and then reverse the layer inside the precomposition. This is the most accurate way to reverse footage. For more information on this process, see “About nesting and precomposing” on page 113.
1 In a Timeline panel, select the layer you want to reverse.
2 Choose Layer Time Time-Reverse Layer, or press Ctrl+Alt+R (Windows) or Command+Option+R (Mac OS).
Reverse keyframes without reversing layer playback You can select and reverse keyframes across multiple layers and properties, but each set of keyframes for a property is reversed only within its original time range and not that of any other selected property. Markers in the Timeline panel are not reversed, so you might need to move markers after reversing keyframes.
1 In the Timeline panel, select a range of keyframes you want to reverse.
2 Choose Animation Keyframe Assistant Time-Reverse Keyframes.
About time-remapping You can expand, compress, play backward, or freeze a portion of a layer’s duration using a process known as timeremapping. For example, if you are using footage of a person walking, you can play footage of the person moving forward, and then play a few frames backward to make the person retreat, and then play forward again to have the person resume walking.
When you apply time-remapping to a layer containing audio and video, the audio and video remain synchronized.
You can remap audio files to gradually decrease or increase the pitch, play audio backward, or create a warbled or scratchy sound. Still-image layers cannot be time-remapped.
Aharon Rabinowitz provides a tutorial that shows how to use time-remapping to do lip-synching; this same basic concept can be used for many kinds of character animation: www.adobe.com/go/learn_ae_aharonlipsynch.
You can remap time in either the Layer panel or the Graph Editor. Remapping video in one panel displays the results
in both. Each provides a different view of the layer duration:
• The Layer panel provides a visual reference of the frames you change, as well as the frame number. The panel displays the current-time indicator and a remap-time marker, which you move to select the frame you want to play at the current time.
AFTER EFFECTS CS3 221 User Guide
• The Graph Editor provides a view of the changes you specify over time by marking your changes with keyframes and a graph similar to the one displayed for other layer properties.