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Motion paths
When
you animate spatial properties—including Position, Anchor Point,
and effect control point properties—the motion is shown as a motion
path. A motion path appears as a sequence of dots, where each dot
marks the position of the layer at each frame. A box in the path
marks the position of a keyframe.
Motion paths are simply an alternative visual, spatial way of
viewing and working with spatial properties and their keyframes,
in addition to the ways that you work with properties in the Timeline
panel. You can modify a motion path by changing an existing keyframe
or adding a new keyframe. You can modify the shape of a motion path
by changing the spatial interpolation methods for its keyframes. (See About spatial and temporal keyframe interpolation.)
The density of dots between the boxes in a motion path indicates
the relative speed of the layer or effect control point. Dots close
together indicate a lower speed; dots farther apart indicate a greater
speed.
Note: Right-click (Windows) or Command-click (Mac OS) a keyframe
to open its context menu.
Using the Pen tool or Selection tool to edit keyframes for a
spatial property in the Composition or Layer panel is like modifying
a Bezier path for a mask or for a shape on a shape layer. (See About paths.)
A motion path is less complex and generally easier to modify
when you use fewer keyframes to describe the path. You can use the
Smoother to remove extraneous keyframes from a motion path.
Jonas Hummelstrand and Dan Ebberts provide an animation preset
and instructions on the General Specialist website for scaling
and rotating a motion path.
Jeff Foster provides a video tutorial on the Adobe website that shows how to adjust
a motion path using the direction handles on each keyframe (vertex)
to change the shape of the Bezier curve.
Show motion path controlsPosition motion paths appear in the Composition
panel. Anchor Point and effect control point motion paths appear
in the Layer panel.
- To show motion path controls in the
Composition panel, choose View > View Options, and select Effect
Controls, Keyframes, Motion Paths, and Motion Handles. To see a
Position motion path in the Composition panel, the Position property
must be selected.
- To show motion path controls in the Layer panel, choose
the property or effect from the View menu at the bottom of the Layer
panel.
- To specify how many keyframes to show for a motion path,
choose Edit > Preferences > Display (Windows) or After Effects
> Preferences > Display (Mac OS), and select an option in
the Motion Path section.
Move motion path keyframes- In the Timeline panel, select the layer
for which to modify the motion path.
- If you cannot see the keyframe you want to modify in
the Composition panel or Layer panel, move the current-time indicator
to the keyframe.
- In the Composition panel or Layer panel, use the Selection
tool to drag a keyframe or its handles.
Note: The current-time indicator does not need to be located
on a keyframe before you drag it.
 Drag a keyframe in the Composition panel to move one Position
keyframe. You can move multiple keyframes at
one time by selecting them in the Timeline panel before you drag
them in the Composition panel or Layer panel. To move the entire
motion path, select all keyframes by clicking the property name
in the Timeline panel before dragging a keyframe in the Composition
panel.
 Dragging all keyframes on a motion path by one keyframe
Add a keyframe to a motion path using the Pen tool- Display the motion
path that you want to modify in the Composition panel or Layer panel.
- Select the Pen tool
or
Add Vertex tool from
the Tools panel.
- In the Composition panel, place the Pen tool over the
motion path where you want to add the new keyframe and click to
add the keyframe.
A new keyframe appears at the frame you clicked, on the
motion path and in the Timeline panel. To move the keyframe, use
the Selection tool. Note: Though the results are different, the techniques
for manipulating motion-path curves with the Pen tool work in much
the same way as the techniques used to create and modify other Bezier
paths, such as mask and shape paths.
Sketch a motion path with Motion SketchYou
can draw a path for the motion of a selected layer using Motion
Sketch, which records the position of the layer and the speed at
which you draw. As you draw, a Position keyframe is generated at
each frame.
Motion Sketch does not affect keyframes that
you have set for other properties. For example, if you set Rotation
keyframes for an image of a ball, you can use Motion Sketch to generate
Position keyframes, so that the ball appears to roll along the path
you created.
- In the Composition or Timeline panel, select the
layer for which you want to sketch a motion path.
- In the Timeline panel, set the work-area markers to the
duration in which you want to sketch motion.
- If you want to hear the audio in your composition as
you sketch, make sure that the Mute Audio button is not selected
in the Preview panel.
- Choose Window > Motion Sketch.
- Select the appropriate Motion Sketch options:
- Show Wireframe
- Displays a wireframe view of the layer as you sketch the motion
path.
- Show Background
- Displays the static contents of the frame at which you started
sketching in the Composition panel while you sketch. This option
is useful if you want to sketch motion relative to other images
in your composition.
- Smoothing
- Eliminates unnecessary keyframes from the motion path. This setting
has the same result as using the Tolerance setting with the Smoother. Higher
values produce smoother curves, but too high a value may not preserve the
shape of the curve that you draw.
Note: You can smooth a motion
path after it has been created by using the smooth expression
or the Smoother.
- Capture Speed At
- The ratio of the speed of the recorded motion to the speed of
playback. If Capture Speed At is 100%, the motion is played back
at the speed at which it was recorded. If Capture Speed At is greater
than 100%, the motion plays back slower than it was recorded.
- Click Start Capture and then drag in the Composition
panel to create the motion path. Release the mouse button to stop
capturing.
Note: After Effects automatically ends capturing when the
capture time reaches the end of the work area (which, by default,
is the composition duration).
Create a motion path from a mask, shape, or paint pathYou can create a motion path from
any of several types of paths:
A Mask Path property
A shape Path property on a shape layer
A Path property for a paint stroke
A path copied from Illustrator or Photoshop
You
can paste any of these paths into the Position or Anchor Point property
for a layer, or into the position property of an effect control
point. The pasted keyframes are set to rove in time, except for
the first and last ones, to create a constant velocity along the
path.
By default, the duration of the pasted motion path
is 2 seconds. You can adjust the duration by dragging the first
or last keyframe in the Timeline panel.
- Copy a path to the clipboard:
Select a Path property in the Timeline
panel, and choose Edit > Copy.
Select a path in Illustrator or Photoshop, and choose
Edit > Copy.
- In the Timeline panel, select the property into which
to paste the path. The property must be animated—that is, it must
have at least one keyframe or an expression.
- Place the current-time indicator at the time for the
first keyframe of the motion path.
- Choose Edit > Paste.
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