This isn’t your simple, run-of-the-mill crossfade. It doesn’t work for all types of backgrounds, but it does work great for a wide variety of imagery. You want to crossfade between two copies of the same layer or comp, but you need to set them up correctly. You want the end of Layer 2 (and the end of the crossfade) to match up with the very beginning of Layer 1 (the beginning of your background).

This is easier than it sounds. The trick is to make sure your movie doesn’t begin with the beginning of Layer 1. Instead, at the beginning of your Background Comp, have Layer 1 pushed back so that it starts at the two-second mark. Your timeline should look like this:

Notice where the triangle is. On Layer 2, it occurs at time 04:00, which is two seconds past where Layer 2 begins. Likewise, notice that the triangle on Layer 1 occurs at time 00:00. This means Layer 1 actually starts two seconds before the beginning of your Comp. So the frame that occurs at time 04:00 is exactly the same frame that occurs at time 00:00. All you need to do now is cross-fade between Layer 1 and Layer 2 and you’ve got a looping background.

How, exactly, you do the crossfade depends on the contents of your background. Sometimes a simple crossfade will do; sometimes, you’ll need to ramp the Opacity of Layer 2 near to 100 percent before starting to fade Layer 1 out (as you’ve done here).

These days, there are some great filters shipping with After Effects that have looping built into them. Fractal Noise, Cell Pattern and Vegas are a few of these plug-ins.

Some filters, like Fractal Noise, have checkboxes that prompt the filter to loop automatically. If you look in the Evolution Options section, you’ll see a Cycle Evolution checkbox. Turn this on. Then set Cycle (In Revolutions) to the number of full revolutions you want to animate the Evolution parameter and have the noise loop seamlessly (for example, set it to two). When you animate the Evolution parameter two full turns (or revolutions, which is 720 degrees), the noise will come back to exactly where it started and look exactly the same.

If you wanted to create an animation that looped over eight seconds, all you would do is animate Evolution by two full revolutions over eight seconds. It’s easy, and makes Fractal Noise the most powerful filter available for creating looping backgrounds.

Filters like Vegas work a bit differently. Vegas uses a Rotation parameter to animate the effect (in some filters Phase works the same way). If you animate Rotation a full 360 degrees (one revolution) the filter will come back to its starting point and create a loop. Wave Warp and Motion Tile are a few of the other filters that work this way.

If you’re using After Effect’s 3D space, you can animate the camera around in a loop. Make sure the camera ends up in exactly the same orientation/position as it started. You’ll need to manually adjust the camera’s animation path to make sure you get the movement you want throughout the animation.

This image, below, is one of the looping backgrounds I’ve included in the backgrounds.aep project download. It uses both Method 3 and 4 to create the full effect.

Sure, this one is kind of obvious, but don’t forget about it. Take the object you’re animating and move it off screen. You can do this either by animating the Position (moving it off screen), Scale or Opacity (fade it out) of the object. Once you make it do just the opposite at the beginning of the background (fading on or coming in from off-screen), you have a looping object.

Jim Tierney
President
Digital Anarchy

Jim Tierney has worked on numerous award-winning products from companies like MetaCreations, Atomic Power and Cycore. After working with Adobe After Effects plug-ins for almost a decade, he thought it was finally time to get out there and create some of his own. As " Chief Executive Anarchist," Jim conceptualizes and designs Digital Anarchy products and heads up business development.

More and more people are using looping backgrounds in projects. The great thing about this is that when a client changes his or her mind and decides the intro needs to be 12 seconds longer, you don’t need to do anything except repeat your looping background a few more times. It certainly helps to make life a bit easier. And in a world with grouchy, penny-pinching, pain-in-the-neck clients (wink, wink), the easy life is not always easy to come by!

Support Gear:
Mac G5, OSX.3.8, Adobe Photoshop, Apple TextEdit

You can download this project file to see even more examples at: