Hawk Eye Makes It Harder for Players to “Pull a McEnroe"
Posted by Christina Folz, OPN managing editor
The rules have changed since that fateful Wimbledon match in 1981, when John McEnroe threw his racquet on the court and yelled at the chair umpire: “You cannot be serious!” Now, when players dispute the line calls at major tournaments, officiators can simply smile and let the ball speak for itself — sort of.
Earlier this year, Wimbledon became the third grand-slam tennis event to adopt a new technology called the Hawk Eye, a system that uses a series of cameras and computers to create virtual replays of disputed calls. The system has introduced a breathtaking level of accuracy into the officiating of the game: During testing by the International Tennis Federation, Hawk Eye was found to have made the correct call in 100 percent of all tests, with an average error of just 3.6 mm.
The system, which is available only for stadium courts, relies on input from multiple high-speed video cameras that capture the path of the ball at a rate of 50 frames per second. Each camera feeds the information into a computer, which uses vision processing to determine the exact center of the ball in each frame. The system compensates for camera movement by also tracking the lines of the court. The two-dimensional information gathered from each camera’s computer is then fed into a mainframe, and the system triangulates the information from each calibrated position to determine the 3-D position of the ball.
This process is repeated for each frame, and the 3-D positions are combined to create a simulation of the trajectory of the ball and determine exactly where it bounced. The ball’s path is transmitted directly to the high-definition screens above the court, so the crowd can find out the resolution of a disputed call at the same moment that the players do.
In matches that have adopted the Hawk Eye system, players typically have two chances per set to challenge calls made by chair umpires, with an extra challenge afforded to each player in the event of a tiebreak. If a player challenges a call and the Hawk Eye simulation shows he is incorrect, he loses one of his challenges. However, if Hawk Eye finds that the player made the right call—and the umpire made the wrong one—the player preserves that challenge opportunity.
According to statistics from the 2006 U.S. Open, only 30.1 percent of men’s challenges, and 35.9 percent of women’s, were upheld after the Hawk Eye was invoked. It’s impossible to know whether McEnroe threw his racquet in vain in his 1981 match against Tom Gullikson—but it’s probably safe to say that at least some of the anger he expressed toward umpires over the years should have been redirected at another source: himself.
The Hawk Eye Sensors site lets you play umpire. See how well you can judge the calls at: http://www.hawkeyesensors.com/judge.cfm
Popular Science offers a Web exclusive on the Hawk Eye system and a photo gallery that shows how the system works: http://www.popsci.com/popsci/technology/01b844f7a848d010vgnvcm1000004eecbccdrcrd.html
The Hawk Eye Innovations Ltd. provides more information about the technology and its applications in tennis, cricket and something called “snooker”: http://www.hawkeyeinnovations.co.uk/
2007-08 August, Optics and pop culture