Hawk-Eye is a computer vision system used to visually track the trajectory of a ball and display a profile of its statistically most likely path as a moving image. It is used in more than 20 major sports, including baseball, cricket, tennis, badminton, hurling, rugby union, soccer, Gaelic football, American football, and volleyball. The Sony-owned Hawk-Eye system was originally developed in the United Kingdom by Paul Hawkins. The system was first implemented in 2001 for television broadcasts, where it was used to analyze leg before wicket decisions in cricket. It works via the use of up to ten high-performance cameras, normally positioned on the underside of the stadium roof, which track the ball from different angles. The video from the cameras is then triangulated and combined to create a three-dimensional representation of the ball's trajectory. Although not infallible, Hawk-Eye is advertised to be accurate to within 2.6 mm (100 thou). Hawk-Eye is increasingly used as an impartial review in sports, having been accepted by governing bodies in tennis, cricket, and association football (soccer) as a means of adjudication. Hawk-Eye has been used for the Challenge System since 2006 in tennis and Decision Review System in cricket since 2009. The system is also used to determine whether the ball has crossed the goal line in football as a means of goal-line technology, implemented in the 2013–14 Premier League season and now present at many domestic leagues and international competitions.
Method of operation All Hawk-Eye systems are based on the principles of triangulation using visual images and timing data provided by a number of high-speed video cameras located at different locations and angles around the area of play. For tennis there are 10 cameras. The system rapidly processes the video feeds from the cameras and ball tracker. A data store contains a predefined model of the playing area and includes data on the rules of the game. In each frame sent from each camera, the system identifies the group of pixels which corresponds to the image of the ball. It then calculates for each frame the position of the ball by comparing its position on at least two of the physically separate cameras at the same instant in time. A succession of frames builds up a record of the path along which the ball has travelled. It also "predicts" the future flight path of the ball and where it will interact with any of the playing area features already programmed into the database. The system can also interpret these interactions to decide infringements of the rules of the game. The system generates a graphic image of the ball path and playing area, which means that information can be provided to judges, television viewers or coaching staff in near real-time. The tracking system is combined with a back-end database and archiving capabilities so that it is possible to extract and analyse trends and statistics about individual players, games, ball-to-ball comparisons, etc.
History Hawk-Eye was developed in 2000 by engineers at Roke Manor Research Limited, then a Siemens subsidiary in Romsey, England. Paul Hawkins and David Sherry submitted a United Kingdom patent application for the technology, but this was subsequently withdrawn. All of the technology and intellectual property was spun off into a separate company, Hawk-Eye Innovations Ltd, based in Winchester, Hampshire. This was initially established as a joint venture between Roke Manor Research and Sunset + Vine. At the time, Sunset + Vine produced the Channel 4 television cricket coverage where Hawk-Eye was first used. On 14 June 2006 a group of investors—led by the Wisden Group and that included Mark Getty, a member of the wealthy American family and business dynasty—bought the company for £4.4m. The acquisition was intended to strengthen Wisden's presence in cricket and allow it to enter tennis and other international sports, with Hawk-Eye working on implementing a system for basketball. According to Hawk-Eye's website, the system produces much more data than that shown on television. Put up for sale in September 2010, it was sold as a complete entity to Japanese electronic giant Sony in March 2011 in a deal that valued the company at £15m-£20m.
Deployment in sport
Cricket
The technology was first used by Channel 4 during a Test match between England and Pakistan on Lord's Cricket Ground, on 21 May 2001. It is used by the majority of television networks to track the trajectory of balls in flight. Its major use in cricket broadcasting is in analysing leg before wicket (LBW) decisions, where the likely path of the ball can be projected forward, through the batsman's legs, to see if it would have hit the stumps. In the winter season of 2008/2009 the ICC trialled a referral system where Hawk-Eye was used for referring decisions to the third umpire if a team disagreed with an LBW decision. Initially the third umpire was able to look at what the ball actually did up to the point when it hit the batsman, but could not look at the predicted flight of the ball after it hit the batsman. The third umpire is now able to see the projected path of the ball too, and Hawk-Eye is currently sanctioned in international cricket even though some doubts remain about its accuracy. When an LBW decision is referred to Hawk-Eye, it assists in assessing against three criteria:
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