Hawk-Eye began as a TV graphic for cricket and became a referee
When a bowler traps a batsman's pad, Hawk-Eye projects where the ball would have gone next, straight through the legs toward the stumps. It started in 2001 as a television gimmick on a Test at Lord's. Today it rules on line calls, goal lines and leg-before-wicket appeals in more than 20 sports.
Engineers at Roke Manor Research, then part of Siemens, built the system in 2000 in Romsey, England, with Paul Hawkins behind the idea. It was spun off as Hawk-Eye Innovations, a joint venture with Sunset + Vine, the production company then making Channel 4's cricket coverage. Channel 4 first showed it during England's Test against Pakistan on 21 May 2001.
The method is triangulation. Up to ten fast cameras, usually tucked under the stadium roof, film the ball from different angles. In every frame, software finds the pixels that make up the ball and compares their position across at least two cameras at the same instant, building a three-dimensional path. It then extends that path forward against a stored model of the playing area and its rules. The makers advertise accuracy within 2.6 millimetres, though it is not infallible.
Officials adopted it gradually. The Hopman Cup in Perth in 2006 became the first elite tennis event to let players challenge line calls, and Jamea Jackson made the first challenge. By the end of 2006 the US Open had followed as the pioneering grand slam. Cricket's review system has used it since 2009; for leg-before-wicket calls it checks where the ball pitched, where it hit the pad and its projected path, and close calls keep the on-field umpire's decision. English football's Premier League brought it in for goal-line decisions in the 2013–14 season.
Ownership changed twice. A Wisden-led group bought the firm on 14 June 2006 for 4.4 million pounds, and Sony acquired it in March 2011 in a deal valuing it at 15 to 20 million pounds.
Source: Hawk-Eye
