CMU grad students build 3-D snowball fight

There were two rules for the teams in the Building Virtual Worlds class: no shooting games and no pornography.

They had a week to develop something in 3-D and five people to do it: two computer programmers, a costume designer, an artist and an industrial engineer.

What they came up with was a 3-D snowball fight in which a player can peek around snow banks and hurl snowballs at little cartoon kids who are about two levels of art up from the "South Park" kids.

The students are all in the first semester of the master's degree program at the Carnegie Mellon Entertainment Technology Center. The goal of the exercise, in addition to building that virtual world, was to show the students they don't need to be good at everything to create a successful computer game, they just need to be really good at something and be able to work with others who have other skills.

Carnegie Mellon's program is like the more famous Massachusetts Institute of Technology's Media Lab, with an important difference, said Drew Davidson, the director of the program. CMU students who come up with ideas own those ideas, and out of that have come some local companies.

The students behind the virtual snowball fight -- Katie Smith, Steve Geist, Charlie Kim, Cooper Yoo and Paulwei Wang -- said the hardest part of the problem was the idea. They were inspired by a video on YouTube by Jimmy Chung Lee, a professor at Carnegie Mellon's Human-Computer Interaction Institute.

Mr. Lee's video, which went online in December 2007, has been viewed by nearly 7.5 million people and shows how, by using a Wii remote and the infrared light emitting sensor bar that normally would sit on top of a TV, you can create games that track the user's head and therefore can seem to be 3-D on a television screen.

This is the concept the student team used for the snowball fight. The sensor bar was attached to Mr. Yoo's head using the decisively low-tech front flap of a hunting cap. Then they put Mr. Yoo in gloves to hold the Wii remote with a styrofoam "snowball" around it. They also built a "snow fort" out of styrofoam bricks to provide some ambience.

Mr. Yoo waved the remote in a throwing motion, ducking behind snowbanks and peaking around them to find virtual kids to target. Each time he landed a virtual snowball, there was a noise from the child who was struck. By the end of the game, he had made 50 kids cry.

The virtual kids get revenge and jeer at players when they get hit. There also is music that could have been used in either of the off-limits applications.

"We were always humming the song," Mr. Geist said.

The team did not use a Nintendo Wii for the computer, instead they used software on a PC and the Wii components.

The goal of the first semester for these students is to show them that they need to work as teams, Mr. Davidson said.

After completing the game, the students were shuffled into other groups to create such things as applications for cell phones, interactive magic shows and a laser-harp performance with Japanese Taiko drumming.

The students learned to work with people with different perspectives. The one thing all of the snowball game team had in common was that they had all seen the late Professor Randy Pausch's last lecture, the lecture in which Mr. Pausch, who was diagnosed as terminally ill with pancreatic cancer, delivered his life lessons to an auditorium at CMU. The lecture has been viewed by more than 10 million people on YouTube.

Ms. Smith said when she saw that lecture and looked into the Entertainment Technology Center that Mr. Pausch helped found, she saw it as a "dream fulfillment factory."

Then she paused a beat or two and said, "That's a pretty great place to come."

Ann Belser can be contacted at or 412-263-1699. First Published November 4, 2009 5:00 AM


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