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Filed under: Motion Graphics •

Visual Rhythm, Part 1: After Effects Tricks

Rhythm - repetition, with variation - is the backbone of many pieces of fine art, as well as motion graphic designs. However, it can be tedious to create and animate hordes of layers - and tedium is not a ticket to inspiration. In the next two columns, we’ll discuss approaches to more easily creating visual rhythm. In this column we’ll start with techniques that can be executed inside Adobe After Effects; in the next column we’ll discuss alternate tools such as Apple Motion and Maxon Cinema 4D.

Simple Swarms

One fun animation style is when a large number of objects all seem to want to occupy the same point in space or follow the same path, but there are random variations between them. This swarming behavior is a version of controlled chaos. In chaos theory, the centerline of this position or path is known as a “strange attractor”: You can predict within what range around the attractor that objects will appear, but you can’t predict precisely where an individual object will appear at a specific point in time.

The random variation is easy to create in After Effects using the wiggle expression. In its simplest form, wiggle needs two numbers: how fast a parameter wiggles, followed by how much it wiggles. For example, to make the position of a layer randomly wander by 50 pixels, at a rate of one wiggle (excursion in a particular direction) per second, reveal the layer’s Position parameter in the Timeline window, Option+click on Mac (Alt+click on Windows) on the animation stopwatch icon next to Position, and type the following expression, followed by the Enter key:

wiggle(1, 50)

You can still keyframe the position of this layer; the wiggle offset will be added to the layer’s keyframed position path. This very same wiggle expression can be applied to virtually any parameter, including a layer’s scale, rotation, or opacity.

If you want one layer to be your strange attractor and to have other layers swarm around it, you can build upon this basic expression. Expose the position property (or whatever property you want to swarm) for both your master and slave layers. Enable expressions for position of the slave layer, and first type (without hitting Enter):

wiggle(1,50) - value +

This gives you a pure wiggle that removes the original position value of the slave layer. To make the slave (loosely) follow the master, place your cursor after the “+” sign, and use the pick whip tool for the slave’s position and drag it to the name of the same parameter for the master layer, followed by hitting Enter. You can animate the master however you like, and the slave will follow.

You won’t always know exactly how fast or much you want to wiggle by before you start. It’s a good idea to add a pair of Effect > Expression Controls > Slider Controls to the master layer, and rename them by selecting their names in the Effect Controls window, hitting return, typing, and hitting return again. Then, instead of entering “1” or “50” inside the parenthesis for the wiggle, drag the pick whip to these sliders in the Effect Controls or Timeline window (see below). You can then edit these two sliders, and affect the behavior of the slave without having to manually edit the expression.

To make the wiggle expression easier to control - especially if you plan to duplicate the layer - link its parameters to an Expression Control applied to a master layer, such as the Slider we used here.

The fun part comes when you duplicate the slave layer multiple times. Each copy will be wiggled slightly different from each other. Duplicate it a bunch of times, and now you have a swarm. Consider using blending modes such as Add or Overlay to make the layers interact where they overlap; colors and partial transparency aid the impact of this effect (see the sequence below). You can also replace the source footage used for any copy of the original layer: Select the layer to replace, select a new footage item in the Project window, and type Command+Option+/ (Control+Alt+/).

A swarm of layers created using the wiggle expression, blended together using Add mode.

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