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An electronic marvel

New Hawk-Eye system brings instant replay to Open

Posted: Friday September 8, 2006 9:55PM; Updated: Friday September 8, 2006 10:53PM
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Open semifinalist Jelena Jankovic would cast a dissenting vote regarding instant replay.
Open semifinalist Jelena Jankovic would cast a dissenting vote regarding instant replay.
Jamie Squire/Getty Images
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NEW YORK (AP) -- Replay: Frequently Asked Questions

We interrupt your regularly scheduled NFL read to bring you the following announcement: The U.S. Open winnows down to its final four this weekend. On the men's semifinal action, top seed Roger Federer faces No. 7 seed Nikolay Davydenko of Russia and No. 9 seed Andy Roddick squares off against Mikhail Youzhny, also of Russia, while No. 3 seed Maria Sharapova plays second-seeded Justine Henin-Hardenne in the women's final. Those tennis fans who haven't been tuning in over the past two weeks will notice a new wrinkle in play -- replay, only without the hood and the red hankie. What exactly is there to replay in tennis, you ask? Plenty. Just keep reading:

How does replay, or Hawk-Eye, work? Hawk-Eye relies on information from 10 fixed close-circuit cameras that track the center of the ball, as well as the lines on the court. Two of them are mounted 115 feet above the court, while the other nine sit at 28 1/2 feet. Data from each of the 10 cameras downloads into 10 separate computers housed, along with the rest of the Hawk-Eye staff -- inside the broadcast booth. The information from those 10 computers is then relayed into one central computer where the point is then re-created in 3-D, with a yellow-green neon tail mark (think the NHL on FOX) and black shadow mark added to show the trajectory of the ball and area the area where it contacted the court. Then that information gets bounced to another computer and reassembled inside what is known as a "virtual world," or a digital 3-D rendering of the court.

The last five shots of a rally are automatically displayed at the end of each point on a screen inside the booth. As soon as a player decides which stroke to challenge (be it the last point or the point before it), the Hawk-Eye operator need only click on the desired point to initiate a replay. The entire process takes about 1-2 seconds -- or a fraction the time it takes to explain. Fans, players and chair umpire all watch the same computer-generated replay image (though slowed to around 10 seconds to build the drama) on the scoreboard.

Which courts feature the system? Just Arthur Ashe and Louis Armstrong, or the only ones at here in Queens with outdoor big screens.

How accurate is it? Hawk-Eye guarantees a margin of error within 3 millimeters, about the width of a ball's fuzz.

Who invented Hawk-Eye? A bloke by the name of Paul Hawkins. (Get it? HAWK-eye?) He originally developed the technology about three years ago for the BBC's cricket coverage. A former player himself, Hawkins was easily riled by the game's subpar (his opinion) officiating and yearned for a system that would clear up the inconsistencies. So the 32-year-old Hawkins, who boasts a doctoral degree in artificial intelligence, made one himself. He sunk about $660,000 into developing a ball-tracking device, then another $950,000 into making it work on TV. The system's success in cricket prompted U.S. and British networks to give it a try in tennis. The first tests of the system were conducted by firing tennis balls with a cannon and comparing Hawk-Eye's imagery with high-speed video, which led to trials at satellite events. Then, the International Tennis Federation gave it the green light last October.