Interpolation is the process of filling in the unknown data between two known values. In digital video and film, this usually means generating new values between two keyframes. For example, if you want a graphic element (such as a title) to move fifty pixels across the screen to the left, and you want it to do so in 15 frames, you’d set the position of the graphic in the first and 15th frames, and mark them both as keyframes. Then the software would complete the work of interpolating the frames in between to make the movement appear smooth. Because interpolation generates all the frames between the two keyframes, interpolation is sometimes called tweening. Interpolation between keyframes can be used to animate movement, effects, audio levels, image adjustments, transparency, color changes, and many other visual and auditory elements.
applies the selected interpolation method to changes in motion. You can use Temporal Interpolation, for example, to determine whether an object moves evenly or accelerates across a motion path. You can apply temporal interpolation of keyframes to only a few effects in Premiere Pro.
applies the selected interpolation method to changes in shape. You can use Spatial Interpolation, for example, to determine whether corners should be rounded or angular. You can apply spatial interpolation to the keyframes of many effects in Premiere Pro.
The two most common types of interpolation are linear interpolation and Bezier interpolation. You can apply either of these types of interpolation, depending on the type of change you want.
Creates an evenly-paced change from one keyframe to another, with each in-between frame given an equal share of the changed value. Changes created with linear interpolation start and stop abruptly and develop at a constant rate between each pair of keyframes.
Allows the rate of change to accelerate or decelerate based on the shape of a Bezier curve, such as gently picking up speed at the first keyframe and then slowly decelerating into the second.
By changing and adjusting keyframe interpolation, you gain precise control over the rate of changes in your animations. You can choose either an interpolation type from a context menu or you can directly change one keyframe type to another by manually adjusting the keyframe or the handles.
You can also use the Ease In and Ease Out commands to quickly adjust keyframe interpolation.
A. Linear spatial keyframe B. Auto Bezier interpolation C. Continuous Bezier interpolation
Lets you manually adjust the shape of the graph, and the rate of change, on either side of a keyframe. You can create very smooth changes using this method.
Creates a smooth rate of change through a keyframe. As you change a keyframe’s value, the Auto Bezier direction handles change to maintain a smooth transition between keyframes.
Creates a smooth rate of change through a keyframe. However, unlike the Auto Bezier interpolation method, Continuous Bezier lets you adjust direction handles manually. As you change the shape of a graph on one side of a keyframe, the shape on the other side of the keyframe changes to maintain a smooth transition.
Changes a property value without gradual transition (sudden effect changes). The graph following a keyframe with the Hold interpolation applied appears as a horizontal straight line.
Although interpolation methods can vary the rate at which a property changes between keyframes, they cannot change the actual duration between keyframes. Duration is determined by the time (or distance in the time ruler) between keyframes.
A. Normal In/Out B. Bezier/Continuous Bezier/Ease In/Ease Out C. Auto Bezier D. Hold
Bezier handles are two-directional controls that change the curve of the line segment between the handle and the next point on either side. The farther you pull a handle from its keyframe (center point), the more the line bends or curves. The curve that you create by dragging the Bezier handle determines how smoothly the effect changes occur as the animation property approaches and leaves a keyframe. These handles offer you more control over animation changes than simply choosing a keyframe interpolation method. You can manipulate Bezier handles in either a Timeline panel, the Effect Controls panel, or the Program Monitor.
- In a Timeline panel, select the clip containing the keyframes you want to adjust, and then do one of the following:
(Timeline panel) Choose the property you want to adjust from the effect menu next to the clip or track name. You adjust the temporal interpolation of a property in a Timeline panel. Select the clip in the Program Monitor if you want to change the spatial interpolation there.
(Effect Controls panel) Select an effect property’s keyframe markers for the keyframes you want to adjust.
If the keyframe uses Linear interpolation, Ctrl-click (Windows) or Command-click (Mac OS) the keyframe in a Timeline panel or Ctrl-click (Windows) or Command-click (Mac OS) the keyframe marker in the Effect Controls panel to change it to Auto Bezier. If you drag the handles, the keyframe changes to Continuous Bezier.
If the keyframe uses Auto Bezier interpolation, Ctrl-click (Windows) or Command-click (Mac OS) the keyframe and drag out a direction handle to change it to Bezier. Bezier interpolation lets you control each direction handle independently. To convert it to Continuous Bezier, just drag a handle.
If the keyframe uses Bezier, Continuous Bezier, or Auto Bezier, Ctrl-click (Windows) or Command-click (Mac OS) the keyframe to change it to Linear. The Bezier handles disappear.
In the Effect Controls panel, you can use the Velocity graph to adjust motion or the rate of change for a value just before and just after a keyframe. Such adjustments can simulate real-world motion. For example, you can change the motion of a clip so that it slows down just before a keyframe and then speeds up just after the keyframe. You can control the values approaching and leaving a keyframe together, or you can control each value separately.
A. Speed controls B. Incoming direction handles C. Outgoing direction handles
To accelerate entering and leaving the keyframe, drag a direction handle up. Both the incoming and outgoing handles move together.
To decelerate entering and leaving the keyframe, drag a direction handle down. Both the incoming and outgoing handles move together.
To accelerate or decelerate entering the keyframe only, Ctrl-click (Windows) or Command-click (Mac OS) the incoming direction handle and drag it up or down.
To accelerate or decelerate leaving the keyframe only, Ctrl-click (Windows) or Command-click (Mac OS) the outgoing direction handle and drag it up or down.
To rejoin the incoming and outgoing handles, Ctrl-click (Windows) or Command-click (Mac OS) them again.
- To increase or decrease the influence of a keyframe value on the previous keyframe, drag the incoming direction handle to the left or right.
- To increase or decrease the influence of a keyframe value on the next keyframe, drag the outgoing direction handle to the right or left.
Influence determines how quickly the Velocity graph reaches the value you set at the keyframe, giving you an additional degree of control over the shape of the graph.