Separate dimensions of Position to animate components individually

By default, each Position property has two or three components, with each holding the value for one of the spatial dimensions (axes). You can separate the components of a Position property into individual properties—X Position, Y Position, and (for 3D layers) Z Position. Separating dimensions allows you to modify or animate the position of a layer along the x axis, y axis, and z axis independently.

For a video tutorial about using the Separate Dimensions command, go to the Adobe website at www.adobe.com/go/lrvid4067_ae.

To decompose selected Position properties into individual X Position, Y Position, and (for 3D layers) Z Position properties, do one of the following:

  • Choose Animation > Separate Dimensions.
  • Right-click (Windows) or Control-click (Mac OS) a Position property and choose Separate Dimensions from the context menu.
  • Click the Separate Dimensions button at the bottom of the Graph Editor.
To recompose a set of individual Position properties into a single Position property with multiple components, use the same commands that you use to separate dimensions.
Important: When you recompose separate Position properties into a single Position property, some information about the motion path and speed is lost, because the multiple Bezier curves used to represent the individual components are collapsed into a single Bezier curve at each keyframe. When you separate dimensions, some information about speed is lost, but the motion path does not change. You should work with separate dimensions or without separate dimensions for each property for an entire project, rather than toggling back and forth.

The decision of whether to work with separate dimensions depends on what you’re trying to accomplish. Using one property for position has the advantage of providing smooth motion more easily. Also, using a single property for position enables the use of roving keyframes, which provides uniform speed. Working with separate dimensions for position sacrifices some of this automatic smoothing to gain greater control of spatial animation. Working with separate dimensions also makes some simulations easier, especially in cases in which the simulated forces acting on a layer are orthogonal (perpendicular) to one another.

For example, if you are animating a ball flying horizontally and bouncing vertically, you can do so more easily by separating dimensions. The X Position property can be animated with two keyframes, one for the start position and one for the end position. This horizontal animation represents the speed of the throw. The Y Position property can be animated with a single expression that simulates the acceleration due to gravity and the vertical bouncing from the floor. A similar example is a boat drifting down a river in a variable crosswind.

Note: After Effects CS3 included a Separate XYZ Position animation preset that accomplished something similar to the Separate Dimensions feature, though the animation preset is not as robust.