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Filed under: Motion Graphics •

Fractal Noise Tutorial

Ping-Pong Looping

If you really want to animate a parameter that otherwise does not loop on its own, one solution is to “ping pong” the parameter: animate it to one value, and then have it return to its original value at the loop point.

Open the comp [Seamless2], and study the keyframes for the Sub Scaling parameter of FractalNoise_soft. If the keyframes are not visible, select this layer and type U.

The Sub Scaling value animates from 40 to 45, as it did in the original design. To make it loop, it is simply returned to the same value by the end of the comp that it had when the animation started. It does this by animating from 40 to 45 in three seconds, and then back to 40 by the end of the comp. The Easy Ease keyframe assistant was applied to all three keyframes to help make the change in direction less abrupt. Note that the same “rules” as on the previous page about setting your final keyframes one frame beyond the end of your timeline still apply!

The scaling rate of change is now doubled from our original design, where it animated from 40 to 45 over six seconds. If you wanted to keep the same rate of change for Sub Scale as in the original, you could change the comp’s duration to 12 seconds and double all the Evolution cycles.

RAM Preview this comp or play the movie at right; you will notice it takes on an interesting inhale/exhale “breathing” pattern. The fact that a second layer on top is also evolving and looping adds to the complexity and removes some of the boredom that might come with only one layer ping ponging its animation back and forth.

Crossfading

A third approach to looping is old-fashioned crossfading, where the image proceeds in a linear manner, and then you just fade a copy of it back over itself that starts the pattern all over again.

Open [Seamless3]. Note this comp has two copies of the FractalNoise_blocky layer. The copy on the bottom plays from 00:00 to 07:00. From 06:00 to 07:00, a duplicate of this layer fades up on top of the original blocky layer. At 07:00 in the comp, this duplicate has faded up to 100%, and is at time 01:00 in its own animation.

Comp marker #1 is set at 01:00 and marker #7 is set at 07:00. Press 1 and 7 on the keyboard (not the keypad) to jump between these two markers and you’ll see that both frames are identical.

For this animation to loop, you must render the section from 01:00 (not 00:00!) to 06:29 (remember, you don’t render the frame at 07:00 or you will repeat the first frame). The result is shown at right. To improve this result, ideally you would have an even longer crossfade.

It is important to note that you do not render the entire animation; you need to repeat some of it for the overlap that creates the loop. That means your loop will be shorter than your source material - so you may need to create your sources to be longer than originally intended, to provide extra material for the crossfade.

This trick can be applied to many other sources as well in order to force them to loop, though with some movies the cross fade may be quite obvious depending on the content.

Once you’ve rendered your seamless loop, import the movie back into After Effects. Select it in the Project panel and go File > Interpret Footage > Main. Set it to Loop as often as necessary; when you click OK the new duration will be reflected at the top of the Project panel.

Further Reading

There are many Fractal Noise tutorials on the web. If you really want to learn how Fractal Noise works underneath the hood, we suggest this tutorial by Chris Zwar (available on Creative Cow).

If you are curious to learn more about a couple of the techniques discussed in this tutorial, we wrote an article for Artbeats.com on “artificial lighting” - click here to download its PDF. We also wrote an article for them on looping footage; click here to download its PDF.

The content contained in our books, videos, blogs, and articles for other sites are all copyright Crish Design, except where otherwise attributed.

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