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Eben Fiske Ostby: Pulling the Strings

[ photo: Eben Fiske Ostby ]

Pulling the Strings

Woody and Buzz. Just hearing their names is enough to provoke a smile. How did two animated characters create such an indelible impression on our collective psyche? Maybe it's because they seem almost human. They have an extraordinary range of expression and motion - thanks to an innovative animation program developed by Eben Ostby '77 and his collaborators at Pixar (William Reeves, Sam Leffler, and Tom Duff - the Marionette Three-Dimensional Computer Animation System.

The characters are modeled in 3-D directly in the computer - at which point they look like grid-creatures. Then "avars" (articulated variables) are attached to the grid, like invisible marionette strings. The avars can be activated by keystrokes to control the characters' movements and expressions. Woody, for example, was designed with more than 700 control functions. The animator's job is to manipulate the controls to breathe life into the character.

If you watch the movie carefully, you'll notice that Buzz and Woody move quite differently, because Buzz was made of plastic and needed to move less flexibly than Woody. Woody had over 100 avars just in his face, which allowed him to express an extraordinarily wide range of emotions. Toy Story - the top grossing film of 1995 - made history as the first full-length animated feature film created entirely on the computer. Ostby and his collaborators won the 1997 Scientific and Engineering Award from the Academy of Motion Picture Arts and Sciences for the development of the Marionette animation system.
ARS Electronica Archive,
Photo credit: Seth Affoumado