Introduction - Computer Animation: Algorithms and Techniques - page 4

1.2 The heritage of animation
In the most general sense, animate

4 means “give life to” and includes live-action puppetry such as that
found on Sesame Street and the use of electromechanical devices tomove puppets, such as animatronics .
History is replete with attempts to bring objects to life. This history is a combination of myth,
deception, entertainment, science, and medicine. Many of the references to animation are in the form
of stories about conjuring a life force into some humanoid form: from Pygmalion to Prometheus to
Wagner's homunculus in Goethe's Faust to Shelley's Dr. Frankenstein. Some of the history is about
trying to create mechanical devices that mimic certain human activity: from Jacque Vaucanson's
mechanical flute player, drummer, and defecating duck in the 1730s toWolfgang von Kempelen's chess
player in 1769 to Pierre Jaquet-Droz's writing automaton of 1774 to the electromechanical humanoid
robots ( animatronics ) popular today. The early mechanisms from the 1700s and 1800s were set in
the milieu of scientific debate over the mechanistic nature of the human body (e.g., L'Homme Machine ,
translated as Man a Machine , was written by Julien Offray de La Mettrie in 1747 and was
quite controversial). This activity in humanoid mechanical devices was propelled by a confluence of
talents contributed by magicians, clock makers, philosophers, scientists, artists, anatomists, glove
makers, and surgeons (see Gaby Wood's book for an entertaining survey on the quest for mechanical
life [ 50 ] ). Here, however, the focus is on devices that use a sequence of individual still images to create
the effect of a single moving image, because these devices have a closer relationship to hand-drawn
animation.

1.2.1 Early devices
Persistence of vision and the ability to interpret a series of stills as a moving image were actively inves-
tigated in the 1800s [ 5 ], well before the film camera was invented. The recognition and subsequent
investigation of this effect led to a variety of devices intended as parlor toys [ 23 ][ 38 ]. Perhaps the
simplest of these early devices is the thaumatrope , a flat disk with images drawn on both sides with
two strings connected opposite each other on the rim of the disk (see Figure 1.1 ) . The disk could be
quickly flipped back and forth by twirling the strings. When flipped rapidly enough, the two images
appear to be superimposed. The classic example uses the image of a bird on one side and the image of a
birdcage on the other; the rotating disk visually places the bird inside the birdcage. An equally primitive
technique is the flip book , a tablet of paper with an individual drawing on each page. When the pages are
flipped rapidly, the viewer has the impression of motion.
One of the most well known early animation devices is the zoetrope , or wheel of life. The zoetrope
has a short fat cylinder that rotates on its axis of symmetry. Around the inside of the cylinder is a
sequence of drawings, each one slightly different from the ones next to it. The cylinder has long vertical
slits cut into its side between each adjacent pair of images so that when it is spun on its axis each slit
allows the eye to see the image on the opposite wall of the cylinder (see Figure 1.2 ). The sequence of
slits passing in front of the eye as the cylinder is spun on its axis presents a sequence of images to the
eye, creating the illusion of motion.

4 A more restricted definition of animation , also found in the literature, requires the use of a sequence of stills to create the
visual impression of motion. The restricted definition does not admit techniques such as animatronics or shadow puppets
under the rubric animation.