This Computer Science Professor’s Work Brought New Life To Toy Story

As a high school student in the 90s, Theodore Kim liked both art and computers. But how can both interests be connected? Kim wasn’t sure how, and then he saw the first “Toy Story” movie, which is one of the earliest films to feature computer animation. That’s when all of the pieces fell into place.

“It wasn’t even a thing before that,” said Kim, associate professor of computer science. “I thought that you couldn’t combine art and engineering in some interesting way, but now it was like ‘Oh, actually you can!’” 

Twenty four years after the first Toy Story movie, the 4th film in the franchise is now available on DVD this week, and Kim’s work is featured in this film.

In this case, it includes an innovation of his that gives life to the pull string that provides Woody (the cowboy voiced by Tom Hanks) his catchphrases. For the first three Toy Story movies, it took a lot of arduous work to get the string to move in a way that looked realistically, and even then, it could look a little too stretchy or awkward at times. Strings have what’s known as anisotropic properties - that is, they contain fibers with varying degrees of resistance. It’s what makes things like breaking wood or plants swaying in the wind tricky to animate.

“Usually, the artist has to go in and sculpt everything by hand, so they have to intuit what the physics is supposed to be, and then animate it by hand,” said Kim, formerly a senior research scientist at PixarResearch, who joined the Computer Science department this summer. “This time around, we figured out the physics of the fibers so that animators can use a simulator to see how it should behave.”

Aside from computer animation, Kim’s work can also be applied in the medical and the aeronautical field.

Head over to Yale to know more about Kim’s work.

(Image Credit: Yale School of Engineering & Applied Science)