Human beings find aural and visual rhythms immensely satisfying. In fact we are pattern seekers and take great pleasure in notions of 'return' and the familiar. Animators have taken advantage of this human disposition.

CYCLES - CUTTING DOWN THE WORK

There are lots of tricks that animators constantly use to cut down the amount of work to be done. Cycles of repeating action are just one of these ways - and whenever animators find an opportunity to include a cycle in a sequence, you can bet they will seize upon it.

Some of the very early cartoons were almost entirely based on cyclic actions, especially when it was discovered that animation could echo the rhythmic patterns found in music. Walt Disney’s 1928 ‘Steamboat Willie’ was the first sound cartoon to amaze audiences of the day with its close synchronism between image and sound. This relationship was exploited to the hilt, (giving rise to the term 'Mickey Mousing' - a sound track which follows exactly what the image is doing) as was the use of cyclic animation which took its cues from the repeated phases and beats of the musical score.

TYPES OF CYCLIC ACTION

Cycles can be cyclic in nature, that is, the artwork is used in order 1,2,3,4 followed by exact repeats of that order again 1,2,3,4 etc. This type of cycle is useful for representing things like a wheel spinning. Cycles may also oscillate. That is the artwork is used in order 1,2,3,4 but then the artwork is used in reverse order 4,3,2,1 to return to the start position again etc - like the motion of a clock pendulum. Or indeed cycles can be random, 1,4,3,1,2,4,3,1,2, etc - to mimic a flag fluttering wildly in a stiff breeze. Using the technique of cycle animation, it is possible for the animator to reuse such a sequence of drawings over and over again to build up screen time without any additional effort. Some cycles may consist of only two drawings, while others may be involve several tens of complex actions.

	Above: an oscillating cycle. Fairings at each end of the above movement, give the illusion of acceleration and deceleration, resulting in a smooth change of direction.
Above: a cyclic cycle. Again, fairings are used to make the blob dwell slightly at the top of its rotation. In other words, the inbetweens are closer together here and are spaced further apart at the bottom of the rotation.	Above: a random cycle. A set of drawings and images are shot in any order at the whim of the camera operator.

SOME EXAMPLES

Roll over the man on the bike to the right to make him ride. There are two cycles here. A 'resting' pant cycle consisting of only 2 drawings with asymmetrical timing, the breath-in pose being held slightly longer, and the riding cycle consisting of 5 drawings. Note the way the bicycle wheels are treated. Lots of fussy spoke detail simply would not work (heavens! the wheels might even appear to go backwards as cart wheels always do in the Westerns - but that's another story). There is however a distinct smudgy blur which helps the eye follow the rotational movement of each wheel.
		This simple 4 drawing cycle can fill the screen with rich motion. It only needs a small number of drawings because of the patternistic repeating elements in its design. One telephone pole, tree, or road line only has to animate into its immediate neighbour, not be animated all the way from infinity. We need to obey the laws of perspective, however. As the elements recede into the distance, not only do they get smaller, but the apparent distance between them also gets progressively smaller. All we need is a foreground element of a truck wobbling about, and the illusion is very strong even though the solution is so simple.

Parts of this machine cycle also work for the same reason as the road example. Each tooth on the large gear animates into the tooth of the next. Because there are many teeth on the big gear, it appears to move slower than the smaller gear. Besides these rotational movements, there are also translational motions as well distortions involving squash and stretch. Some parts move smoothly, while others like the rocker thingo at the back, which has an oscillating arc movements, has a thump to it courtesy of the arrangement of its fairings. An amazing richness and variety of motion is coming from just 6 drawings.

A minimum of 3 drawings are needed to establish a direction of rotation as in the fan example (right) and will keep it spinning forever. Two drawings create a back and forth oscillating motion which can be ambiguous when used for rotation.

4 drawings keep this lady's hair blow'n in the wind of the fan. The tips of her hair is a collection of wild shapes, while the decorative line work starting at her forehead has ripples running through them to give the wind a sense of direction.

Grass bobbing in the wind, waves lapping on the shore, repetitive human or animal actions and the workings of machines are just some examples of motion which can be convincingly represented by a repeating series of drawings. These complex movements can be represented through forms of abstraction. Rhythmic visual patterns are also very meditative to look at.

		There are also two cycles involved in the movement of these reeds in the wind (left). One cycle picks up the reed as the wind blows stronger, while a second cycle sustains the action as though fluttering in a constant breeze. Exactly the same animation is used for the 5 reeds, but each is out of phase by a couple of frames not only to make the animation far richer to look at, but to suggest that the wind blows from the left and affects each reed at a slightly different moment in time - the Mexican wave effect. The sparkle on the moonlit lake is also a cycle - an effect which was created automatically by pulling one piece of artwork across some randomly placed holes in another. By the way, there are only 8 colours in this scene.
A 3D version of a rich patternistic cycle (right). The apparent complexity of motion within this sequence comes largely through the cloning of one red frond and one green stem and the way the staggered timing of these elements move across each other. This test was made in 1985 during research into 3D computer animation.