Each layer has properties, many of which you can modify and animate. The basic group of properties that every layer has is the Transform group, which includes Position and Opacity properties. When you add certain features to a layer—for example, by adding masks or effects, or by converting the layer to a 3D layer—the layer gains additional properties, collected in property groups.

All layer properties are temporal—they can change the layer over time. Some layer properties, such as Opacity, have only a temporal component. Some layer properties, such as Position, are also spatial—they can move the layer or its pixels across composition space.

You can expand the layer outline to display layer properties and change property values.

Most properties have a stopwatch . Any property with a stopwatch can be animated—that is, changed over time. (See About animation, keyframes, and expressions.)

Collapsed property group (left) compared to expanded property group (right) in layer outline

Properties in the Effects property group (effect properties) are also layer properties. Many effect properties can also be modified in the Effect Controls panel.

If multiple layers are selected and you change a property for one layer, then the property is changed for all selected layers. Sliders, angle controls, and some other property controls are only available in the Effect Controls panel.

To change the units for a property, right-click (Windows) or Control-click (Mac OS) the underlined value, choose Edit Value, and choose from the Units menu. The available units are different for different property types. You can’t change the units for some properties.

Alan Shisko provides a video tutorial on his Motion Graphics 'n Such blog shows how to use label colors and multiple selections to rapidly change properties for multiple layers simultaneously.

Charles Bordenave (nab) provides a script on the After Effects Scripts website that sets the properties in the Transform group for selected layers to random values within constraints that you set.

The LockProperties script, available from the After Effects Scripts website, locks only specified properties so that you can prevent accidental changes.

Transformations, such as rotation and scale, occur around the anchor point (sometimes called transformation point or transformation center) of the layer. By default, the anchor point for most layer types is at the center of the layer.

Though there are times when you’ll want to animate the anchor point, it’s most common to set the anchor point for a layer before you begin animating. For example, if you’re animating an image of a person made up of one layer for each body part, you’ll probably want to move the anchor point of each hand to the wrist area so that the hand rotates around that point for the whole animation.

The easiest way to pan and scan over a large image is to animate Anchor Point and Scale properties.

Alan Shisko provides a detailed video tutorial on his website, demonstrating how to create a complex 3D environment from 3D layers, beginning with simple 2D assets. Manipulating layer anchor points is a crucial part of this tutorial.

Anchor point in center of text layer (left) compared to anchor point moved to the end of the text layer (right)

When you use the Pan Behind (Anchor Point) tool to move the anchor point in the Composition panel (left), After Effects automatically compensates for the move so that the layer maintains its position relative to the composition frame (right).

As with other transformations, scaling of a layer occurs around the anchor point of the layer. If you move the anchor point away from the center of the layer, the layer may move when you flip it. Some layers—such as camera, light, and audio-only layers—don’t have a Scale property.

You can scale a layer beyond the composition frame.

For information on scaling exponentially, as with a zoom lens, see Use Exponential Scale to change the speed of scaling.

For information on scaling or resizing entire movies rather than a single layer, see Scaling a movie up and Scaling a movie down.

To flip a layer is to multiply the horizontal or vertical component of its Scale property value by -1. A layer flips around its anchor point.

Scaling down a raster (non-vector) layer sometimes causes a slight softening or blurring of the image. Scaling up a raster layer by a large factor can cause the image to appear blocky or pixelated.

Adobe Photoshop provides fine control over resampling methods used for scaling of images. For fine control of resampling, you can export frames to Photoshop to change the image size and then import the frames back into After Effects.

Though it's not very well suited for movies, the content-aware scaling feature in Photoshop is very useful for extending and scaling still images. This feature can be useful when repurposing images for wide-screen formats that were created for standard-definition formats.

For a list of plug-ins that provide high-quality scaling—including some designed to create high-definition images from standard-definition sources—go to the Toolfarm website.

For a script that scales multiple compositions simultaneously, go to the AE Enhancers forum.

Lloyd Alvarez provides a script on the After Effects Scripts website that scales selected layers to fit the composition frame, and provides options for cropping or letterboxing.

Aharon Rabinowitz provides a video tutorial on the Creative COW website that demonstrates the uses of changing and animating a 3D layer's Scale property, including changing only the z dimension of Scale.

As with other transformations, rotation of a layer occurs around the anchor point of the layer.

To reveal the Rotation property value for selected layers in the Timeline panel, press R.

The first part of the Rotation property value is the number of whole rotations; the second part is the fractional rotation in degrees.

For information on rotating 3D layers, see Rotate or orient a 3D layer.

When you use footage containing audio, the default audio level for playback is 0 dB, meaning that the level is unadjusted in After Effects. Setting a positive decibel level increases volume, and setting a negative decibel level decreases volume.

The VU meter in the Audio panel displays the volume range for the audio as it plays. The red blocks at the top of the meter represent the volume limit of your system.

For more precision in setting audio levels by dragging sliders, increase the height of the Audio panel.

To synchronize changes to layers by assigning one layer’s transformations to another layer, use parenting. After a layer is made a parent to another layer, the other layer is called the child layer. When you assign a parent, the transform properties of the child layer become relative to the parent layer instead of to the composition. For example, if a parent layer moves 5 pixels to the right of its starting position, then the child layer also moves 5 pixels to the right of its position. Parenting is similar to grouping; transformations made to the group are relative to the anchor point of the parent.

Parenting affects all transform properties except Opacity: Position, Scale, Rotation, and (for 3D layers) Orientation.

A layer can have only one parent, but a layer can be a parent to any number of layers in the same composition.

You can animate child layers independent of their parent layers. You can also parent using null objects, which are hidden layers.

You cannot animate the act of assigning and removing the parent designation—that is, you cannot designate a layer as a parent at one point in time and designate it as a normal layer at a different point in time.

When you create a parenting relationship, you can choose whether to have the child take on the transform property values of the parent or retain its own. If you choose to have the child take on the transform property values of the parent, the child layer jumps to the parent’s position. If you choose to have the child retain its own transform property values, then the child stays where it is. In both cases, subsequent changes to the transform property values of the parent are applied to the child. Similarly, you can choose whether the child jumps when the parenting relationship is removed.

Dragging the pick whip in the Timeline panel to designate the planet layer as the parent to the saucer layer

To assign a parent layer, but keep that layer from being a visible element in your project, use a null object. A null object is an invisible layer that has all the properties of a visible layer so that it can be a parent to any layer in the composition. Adjust and animate a null object as you would any other layer. You use the same commands to modify settings for a null object that you use for a solid-color layer (Layer > Solid Settings).

You can apply Expression Controls effects to null objects and then use the null object as a control layer for effects and animations in other layers. For example, when working with a camera or light layer, create a null object layer and use an expression to link the Point Of Interest property of the camera or light to the Position property of the null layer. Then, you can animate the Point Of Interest property by moving the null object. It is often easier to select and see a null object than it is to select and see the point of interest.

A composition can contain any number of null objects. A null object is visible only in the Composition and Layer panels and appears in the Composition panel as a rectangular outline with layer handles. Effects are not visible on null objects.

If a null object is visually distracting in your composition frame, consider dragging it out of the frame, onto the pasteboard.

Andrew Kramer provides a video tutorial on his Video Copilot website that demonstrates the use of a null object to animate a 3D stroke.

Guy Chen provides a simple project on the After Effects Exchange on the Adobe website that demonstrates the animation of several 3D layers arranged as a cube, controlled by a parent null layer.

Angie Taylor provides an extensive discussion and explanation of animation using parenting, expressions, and null object layers in a PDF excerpt from her book Creative After Effects 7: Workflow Techniques for Animation, Visual Effects, and Motion Graphics.

You can create guide layers from existing layers to use for reference in the Composition panel, to help you position and edit elements. For example, you can use guide layers for visual reference, for audio timing, for timecode reference, or for storing comments to yourself.

A guide layer icon appears next to the name of a guide layer or its source in the Timeline panel.

By default, guide layers aren’t rendered when you create output but can be rendered when desired by changing the render settings for the composition.

Brainstorm creates multiple temporary variants of your composition and displays them in a grid. You can save any number of these variants, apply one to the current composition, or redo the Brainstorm operation using only the variants that you choose as input.

Brainstorm uses genetic algorithms to mutate and select property values used as input into each Brainstorm operation. You decide which variants to include as input to each generation and how much mutation (randomness) to use.

Aharon Rabinowitz provides a video tutorial on the Creative COW website that demonstrates the use of Brainstorm.

Brainstorm dialog box in Randomness mode

A.

Original composition (original in center tile when using Brainstorm on single numeric value)

B.

Maximize Tile

C.

Save As New Composition

D.

Apply To Composition

E.

Use In Next Brainstorm

F.

Randomness control (Spread control when using Brainstorm on single numeric value)

G.

Back and Forward to previous and next generations

H.

Playback controls

With Brainstorm, you can rapidly accomplish the following:

• Compare the results of multiple values for a single property so that you can find the value that works best.

• Explore the results of randomly modifying any number of properties to achieve a creative result.

Open a template project or apply an animation preset to a layer, select some properties (or entire property groups), and then use Brainstorm to quickly modify these properties. Starting from such complete material, you can use Brainstorm to very quickly create your own projects and animations.

You can use Brainstorm on any number of properties and property groups, from one or more layers in the same composition. For example, you can use Brainstorm to refine the single Stroke Width property for a star on a shape layer; or you can select the entire Contents property group and use Brainstorm to explore the entire space of properties for all shapes on the layer.

You can use Brainstorm on any property that has numeric values or options in a pop-up menu in the Timeline panel. Examples of properties on which you can’t use Brainstorm are Source Text, Mask Path, and the Histogram property for the Levels effect; however, you can use Brainstorm on the properties of the Levels (Individual Controls) effect.

Brainstorm operates on all selected keyframes. For a property with no keyframes, Brainstorm operates on the global, constant value.

If you use Brainstorm on a single one-dimensional property (such as Opacity, but not Position), the Randomness value that controls the amount of variation (mutation) is replaced by a Spread value. The variants that are presented in the Brainstorm dialog box are then not random, but represent a range of values around the central value. The original composition appears in the center tile of the dialog box, and you can only select one variant on which to base the next Brainstorm operation.

Though you can’t directly use Brainstorm on expressions, you can use Brainstorm on the properties of Expression Control effects, to which expressions can refer.