Three professional tennis associations, the USTA, the ATP and the WTA, will begin to use instant replay technology from Hawk-Eye Innovations this year - the first tournament to use the system being the NASDAQ-100 Open in Miami, starting next week.
The US Open will become the first Grand Slam event to use the system in August. Dr. Paul Hawkins, Hawk-Eye Innovations managing director, says the system uses eight off-the-shelf high-speed, high-resolution video cameras placed around the court to shoot video of the tennis ball from all angles. The black-and-white cameras each grab their own data that is then used to build a 3D model of the ball's location. Data from all eight cameras is then sent to a central IBM computer to compute a final model that determines whether the ball was in or out. Hawkins says the use of black-and-white cameras is critical as it makes it easier to find the centre of the ball. Images of the ball, he says, are about 10 pixels in size and the high-speed cameras can find the centre of the ball to about one-fifteenth of a pixel.
"This system originally started out as a broadcast enhancement," he said. "That was the perfect training ground where we could get the systems to be accurate all of the time." The replay rules give each player two challenges per set. If the player is correct with a challenge, then he/she will keep the same number of challenges. If the player is incorrect with a challenge, then one will be lost. In a tiebreak situation, each player will receive one additional challenge.
Hawkins says a replay booth will be located near the commentary booths at tournaments. When a player challenges a call the replay booth will then generate a replay and it will be played on the scoreboard for all to see. "This won't be like the NFL where a referee looks at a replay to make a call," he says. "It will be definitive and after the replay a graphic will be shown that says whether the ball was in or out."
Reaction from players has been good, says Hawkins. John McEnroe, for example, recently took part in a tournament where the system was used for the TV broadcast. During the first few days McEnroe was his typical self, berating the linesmen. But once TV coverage began, and the system was available for replays his demeanor changed and he became much more accepting of calls that didn't go his way.
"There's a lot of responsibility on our shoulders because there are a lot of players who work very hard and we have to make sure we can have this system become an accepted part of tennis," says Hawkins. "It takes a long time to build up credibility but only a short time to lose it.