Editing a Motion Path
Once you have created it, you can adjust a motion path directly in the Canvas (or Viewer) by moving or deleting motion path keyframes. When you're working with a motion path in the Canvas, the playhead doesn't need to be over a keyframe for you to move or delete it, nor does the playhead location prohibit you from adding a motion path keyframe. Remember that a keyframe is like an edit point: It signals a change in an effect. In a motion path, keyframes are placed automatically only when a motion path changes direction. A straight motion path requires only two keyframes: a start keyframe and an end keyframe. The two motion path variables you are adjusting are your clip's speed of travel (determined by the ratio of duration to distance between keyframes) and the path's route (indicated by the shape of the white line that connects the start and end keyframes). The little dots that appear between the keyframes indicate the duration between path points.
Adjusting motion path curves and corners
Final Cut Express features two types of motion path keyframes: corners and curves. The default motion path keyframe is a corner, which creates an instant change in direction. If you want a smoother motion effect, the curve keyframes have Bézier handles, which you can use to fine-tune the shape of the path's curve, as well as ease handles, which you can use to fine-tune your clip's speed immediately before and after the keyframe location. You switch a corner type motion path keyframe to a curve type as the first step in smoothing your motion path and finessing its timing.
Tip To toggle a keyframe between corner and curve types in Wireframe mode: With your clip displayed in Wireframe mode in the Canvas, Control-click a keyframe and choose one of the following options:
Figure 15.54 ).
Figure 15.54. Control-click a keyframe on the Canvas; then choose Make Corner Point to toggle the keyframe from a curve type to a corner type.
|
Ease In/Ease Out accesses the ease handles, which are discussed later in this section.Linear applies a constant rate of speed to the path immediately before and after the keyframe location.Delete Point deletes the keyframe.
Adjusting speed along a motion path
You can increase the speed of a clip's movement by shortening the timecode duration between two keyframes without changing their spatial coordinates. The clip's speed increases, since it takes less time to travel between the two locations on your motion path. Or keep the time interval the same and move the keyframes farther apart on the motion path, so the clip travels farther in the same amount of time. Other timing factors in your sequence composition will dictate your choice.
Ease handles, located in the Canvas between the Bézier handles and the keyframe's position point (Figure 15.55 ), fine-tune the rate of speed at which a clip approaches and leaves a curve keyframe. The default Ease In and Out setting slows the speed on the motion path by 33 percent before and after the keyframe, but you can customize that setting. Drag both handles to set the clip's ease in and ease out to the same rate, or drag the handles separately to set different ease-in and ease-out rates.
Figure 15.55. Ease handles are located about midway between the Bézier handles and the keyframe's position point.
Setting a Single Motion Path for Multiple Clips
How can you easily apply a single motion path to multiple clips? A couple of different techniques are available; your choice depends on whether you are dealing with a series of clips on a single track or with multiple clips stacked in layers on Timeline tracks. One approach is to copy and paste just the series of clips into a separate sequence, which you edit back into your main sequence just as if it were a single clip. You can then apply a single motion path to the entire series, because it's contained in a single sub-sequence. You can use the same technique to convert multiple layers into a sub-sequence in order to apply a single motion path. You also have the option of copying a clip and pasting only its motion path using the Paste Attributes function. For more information on working with multiple sequences, see Chapter 4, "Projects, Sequences, and Clips." For more information on the Paste Attributes feature, see Chapter 10, "Editing in the Timeline and the Canvas." |
To make a clip ease in and out of a keyframe:
1. | With the Canvas in Image+Wireframe mode, start with a curve motion path keyframe. |
2. | Choose the Selection tool. |
3. | Click the curve keyframe; then do one of the following: - Drag the ease handle away from the keyframe to increase the clip's speed as it passes through the keyframe's location on the motion path (Figure 15.56 ).
Figure 15.56. Drag the ease handle away from the keyframe to increase a clip's speed as it passes through the keyframe's location on the motion path.
- Drag the handle toward the keyframe to slow the clip's speed as it passes through the keyframe's location on the motion path (Figure 15.57 ).
Figure 15.57. Drag the ease handle toward the keyframe to decrease a clip's speed as it passes through the keyframe's location on the motion path.
- Drag either ease handle to adjust the path's timing on both sides of the keyframe equally.
- Shift-drag one ease handle to adjust the path's timing only on the selected side.
|
4. | Play back in Image+Wireframe mode to see your results. |