Editing Hawk-Eye (section)

===Tennis===
: ''For a history of electronic line calling in tennis, see [[Electronic line judge]]''

[[File:Hawk-Eye at Wimbledon (7508887344).jpg|thumb|Hawk-Eye decision shown on the big screen at Wimbledon.]]
In [[Serena Williams]]'s quarter final loss to [[Jennifer Capriati]] at the [[2004 US Open – Women's singles|2004 US Open]], three line calls went against Williams in the final set (an Auto-Ref system was being tested during the match). Though the calls were not reversed, there was one overrule of a clearly incorrect line umpire call, by the chair umpire [[Mariana Alves]], that the TV replay showed to be good. These errors prompted talks about line calling assistance especially as the Auto-Ref system was being tested by the U.S. Open at that time and was shown to be very accurate.<ref>[http://www.popularmechanics.com/outdoors/sports/technology/cameras-fouls-and-referees Can Cameras and Software Replace Referees?"] ''Popular Mechanics''. (12 May 2010). Retrieved on 3 September 2010.</ref>

In late 2006 Hawk-Eye was tested by the [[International Tennis Federation]] (ITF) in New York City and was passed for professional use. Hawk-Eye reported that the New York tests involved 80 shots being measured by the ITF's high speed camera, a device similar to MacCAM.  During an early test of the system at an exhibition tennis tournament in Australia (seen on local TV), there was an instance when the tennis ball was shown as "Out", but the accompanying word was "In".{{Citation needed|date=June 2009}} This was explained to be an error in the way the tennis ball was shown on the graphical display as a circle, rather than as an ellipse.{{Citation needed|date=June 2009}} This was immediately corrected.

Hawk-Eye has been used in television coverage of several major tennis tournaments, including [[The Championships, Wimbledon|Wimbledon]], the [[Queen's Club Championships]], the Australian Open, the [[Davis Cup]] and the [[Tennis Masters Cup]].  The [[US Open (tennis)|US Open Tennis Championship]] announced they would make official use of the technology for the [[2006 US Open (tennis)|2006 US Open]] where each player receives two challenges per set.<ref>[http://www.usopen.org/en_US/news/articles/2006-08-10/200608101155219422122.html] {{webarchive|url=https://web.archive.org/web/20060821194409/http://www.usopen.org/en_US/news/articles/2006-08-10/200608101155219422122.html|date=21 August 2006}}</ref> It is also used as part of a larger tennis simulation implemented by [[IBM]] called PointTracker.

The [[2006 Hopman Cup]] in [[Perth, Western Australia]], was the first elite-level tennis tournament where players were allowed to challenge point-ending line calls, which were then reviewed by the referees using Hawk-Eye technology. It used 10 cameras feeding information about ball position to the computers. [[Jamea Jackson]] was the first player to challenge a call using the system.

In March 2006, at the [[2006 NASDAQ-100 Open|Nasdaq-100 Open]] in [[Key Biscayne, Florida]], Hawk-Eye was used officially for the first time at a tennis tour event. Later that year, the [[2006 US Open (tennis)|US Open]] became the first grand-slam tournament to use the system during play, allowing players to challenge line calls.<ref>{{cite news |title=Fish first to use replay in Slam |url=http://news.bbc.co.uk/sport2/hi/tennis/5293942.stm |access-date=14 January 2022 |publisher=BBC Sport |date=28 August 2006}}</ref>

The [[2007 Australian Open]] was the next grand-slam event to implement Hawk-Eye in challenges to line calls, where each tennis player in Rod Laver Arena was allowed two incorrect challenges per set and one additional challenge should a tiebreak be played. In the event of an advantage final set, challenges were reset to two for each player every 12 games, i.e. 6-all, 12-all, etc. Controversies followed the event as at times Hawk-Eye produced erroneous output. In 2008, tennis players were allowed three incorrect challenges per set instead. Any leftover challenges did not carry over to the next set. Once, [[Amélie Mauresmo]] challenged a ball that was called in, and Hawk-Eye showed the ball was out by less than a millimetre, but the call was allowed to stand. As a result, the point was replayed and Mauresmo did not lose an incorrect challenge.

[[Image:Hawk eye.svg|thumb|alt=Ball compared with impact.|Ball compared with impact.]]

The Hawk-Eye technology used in the [[2007 Dubai Tennis Championships]] had some minor controversies. Defending champion Rafael Nadal accused the system of incorrectly declaring an out ball to be in following his exit. The umpire had called a ball out; when [[Mikhail Youzhny]] challenged the decision, Hawk-Eye said it was in by {{nowrap|3 mm}}.<ref>{{cite news |author=Barry Wood |url=http://www.nzherald.co.nz/section/4/story.cfm?c_id=4&objectid=10426649 |title=Tennis: Nadal blames line calling system for losing – 02 Mar 2007 – nzherald: Sports news – New Zealand and International Sport news and results |publisher=nzherald |date=2 March 2007 |access-date=1 June 2009 |archive-date=29 September 2007 |archive-url=https://web.archive.org/web/20070929222401/http://www.nzherald.co.nz/section/4/story.cfm?c_id=4&objectid=10426649 |url-status=dead }}</ref> Youzhny said after that he himself thought the mark may have been wide but then offered that this kind of technology error could easily have been made by linesmen and umpires. Nadal could only shrug, saying that had this system been on clay, the mark would have clearly shown Hawk-Eye to be wrong.<ref name="Archive.gulfnews.com">{{cite web|url=http://archive.gulfnews.com/indepth/dubaitennis2007/men/10108379.html |title=Gulfnews: Hawk-Eye leaves Nadal and Federer at wits' end |publisher=Archive.gulfnews.com |date=3 March 2007 |access-date=1 June 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090129111245/http://archive.gulfnews.com/indepth/dubaitennis2007/men/10108379.html |archive-date=29 January 2009 }}</ref> The area of the mark left by the ball on hard court is a portion of the total area that the ball was in contact with the court (a certain amount of pressure is required to create the mark).{{Citation needed|date=July 2010}}

The [[2007 Wimbledon Championships]] also implemented the Hawk-Eye system as an officiating aid on [[Centre Court]] and Court 1, and each tennis player was allowed three incorrect challenges per set. If the set produced a tiebreak, each player was given an additional challenge. Additionally, in the event of a final set (third set in women's or mixed matches, fifth set in men's matches), where there is no tiebreak, each player's number of challenges was reset to three if the game score reached 6–6, and again at 12–12. [[Teymuraz Gabashvili]], in his first round match against [[Roger Federer]], made the first-ever Hawk-Eye challenge on Centre Court. Additionally, during the finals of Federer against [[Rafael Nadal]], Nadal challenged a shot which was called out. Hawk-Eye showed the ball as in, just clipping the line. The reversal agitated Federer enough for him to request (unsuccessfully) that the umpire turn off the Hawk-Eye technology for the remainder of the match.<ref>{{cite news| url=http://www.timesonline.co.uk/tol/sport/tennis/article2051307.ece | work=The Times | location=London | title=Hawk-Eye creator defends his system after Federers volley | first=Will | last=Pavia | date=10 July 2007 | access-date=4 May 2010}}{{dead link|date=September 2024|bot=medic}}{{cbignore|bot=medic}}</ref>

In the [[2009 Australian Open]] fourth round match between Roger Federer and [[Tomáš Berdych]], Berdych challenged an out call. The Hawk-Eye system was not available when he challenged, likely due to a particularly pronounced shadow on the court. As a result, the original call stood.<ref>{{cite web|url=http://www.thaindian.com/newsportal/sports/berdych-joins-federer-in-anti-hawk-eye-club_100147546.html|title=Berdych joins Federer in anti-Hawk-Eye club|date=27 January 2009|access-date=29 June 2009|archive-date=21 September 2012|archive-url=https://web.archive.org/web/20120921100537/http://www.thaindian.com/newsportal/sports/berdych-joins-federer-in-anti-hawk-eye-club_100147546.html|url-status=dead}}</ref>

In the [[2009 Indian Wells Masters]] quarterfinals match between [[Ivan Ljubičić]] and [[Andy Murray]], Murray challenged an out call. The Hawk-Eye system indicated that the ball landed on the centre of the line despite instant replay images showing that the ball was clearly out. It was later revealed that the Hawk-Eye system had mistakenly picked up the second bounce, which was on the line, instead of the first bounce of the ball.<ref>{{cite news|url=https://www.theglobeandmail.com/incoming/when-computers-get-it-wrong/article782529/ |title=When computers get it wrong |date=24 March 2009 |access-date=8 July 2012 |work=[[The Globe and Mail]] |location=Toronto}}</ref> Immediately after the match, Murray apologised to Ljubicic for the call, and acknowledged that the point was out.

The Hawk-Eye system was developed as a replay system, originally for TV broadcast coverage. As such, it initially could not call ins and outs live.The representation of the trajectory results in terms of where the ball lands is called '''Shot Spot'''.<ref>{{cite web |date=7 June 2011 |title=Hawkeye and Shot Spot Technology on All Surfaces: The Red Clay Controversy |url=https://bleacherreport.com/articles/725997-hawkeye-and-shot-spot-technology-on-all-surfaces-the-red-clay-controversy |access-date=17 April 2019 |website=bleacherreport.com}}</ref>

The Hawk-Eye Innovations website<ref>{{cite web |url=http://www.hawkeyeinnovations.co.uk/?page_id=1011 |title=Home :: Hawk-Eye |publisher=Hawkeyeinnovations.co.uk |access-date=2 June 2012 |archive-date=31 August 2011 |archive-url=https://web.archive.org/web/20110831091635/http://www.hawkeyeinnovations.co.uk/?page_id=1011 |url-status=dead }}</ref> states that the system performs with an average error of {{nowrap|3.6 mm}}. The standard diameter of a tennis ball is {{nowrap|67 mm}}, equating to a 5% error relative to ball diameter. This is roughly equivalent to the fluff on the ball.

Hawk-Eye has developed a technology called 'Hawk-Eye Live', which uses the 10 cameras to call shots in or out in real time, with an 'out' call being signified by a speaker emitting an 'out' sound that emulates a human line judge. The technology was initially expected to be in place for the 2019 US Open. The [[2021 Australian Open]] was the first Grand Slam tournament to use Hawk-Eye Live for all matches in place of line judges, in part to reduce personnel during the [[COVID-19 pandemic]], followed by the US Open later that year. Previously, the 2020 US Open used Hawk-Eye in place of line judges for all matches except those held at [[Arthur Ashe Stadium]] and [[Louis Armstrong Stadium]].<ref>{{cite web|url=https://www.sportingnews.com/au/tennis/news/australian-open-2021-technology-to-replace-linespeople-at-australian-open/1xtpxbe6cbkku1p3xba29yidg3 |title=Australian Open 2021: Technology to replace linespeople at Australian Open |date=8 February 2021 |publisher=Sporting News |access-date=18 February 2021}}</ref>

Clay court tournaments, notably the [[French Open]], are generally free of Hawk-Eye technology due to marks left on the clay where the ball bounced to evidence a disputed line call. Chair umpires are then required to get out of their seat and examine the mark on court with the player by their side to discuss the chair umpire's decision.<ref>{{cite web|url=https://www.essentiallysports.com/why-is-hawk-eye-not-used-at-french-open-2020-atp-wta-tennis-news/ |title= Why is Hawk-Eye Not Used at the French Open 2020? |date= 23 September 2020 |access-date=19 February 2021}}</ref> The [[2021 Mutua Madrid Open]] became the first major tournament on clay to use an electronic system to check the bounce of the ball on the court when in doubt in the two main stadiums (Manolo Santana Stadium and Arantxa Sánchez Vicario Stadium at [[Caja Mágica]]).<ref>{{cite web |title=El Mutua Madrid Open contará con la Revisión Electrónica de FOXTENN |url=https://www.madrid-open.com/noticias-mutua/el-mutua-madrid-open-contara-con-la-revision-electronica-de-foxtenn/ |website=Madrid-open.com |access-date=29 May 2021 |location=Madrid |language=es |date=9 February 2021}}</ref> The system was developed by FoxTenn, a Spanish company located in [[Barcelona]]. It uses real images of the ball captured by 40 cameras located at ground level, synchronized with lasers and working at up to 3,000 images per second to determine whether it has bounced in or out of the court's limits.<ref>{{cite news |last=Albarrán |first=Nacho |title=Foxtenn: 40 ojos que suplen las bajadas de los jueces |url=https://as.com/tenis/2021/05/03/masters_1000/1620043372_262867.html |access-date=29 May 2021 |work=AS |date=3 May 2021 |location=Madrid |language=es}}</ref> This system was previously used at the [[2020 Rio Open]] in [[Rio de Janeiro]] and at the [[2021 MUSC Health Women's Open]] in [[Charleston, South Carolina]].

====Unification of rules====
Until March 2008, the International Tennis Federation (ITF), [[Association of Tennis Professionals]] (ATP), [[Women's Tennis Association]] (WTA), [[Grand Slam (tennis)|Grand Slam]] Committee, and several individual tournaments had conflicting rules on how Hawk-Eye was to be utilised. A key example of this was the number of challenges a player was permitted per set, which varied among events.<ref name="tind1">{{cite news|url=https://www.independent.co.uk/sport/tennis/hawkeye-makes-history-thanks-to-rare-british-success-story-at-wimbledon-454677.html|archive-url=https://archive.today/20110818091248/http://www.independent.co.uk/sport/tennis/hawkeye-makes-history-thanks-to-rare-british-success-story-at-wimbledon-454677.html|url-status=dead|archive-date=18 August 2011|title=Hawk-Eye makes history thanks to rare British success story at Wimbledon|work=[[The Independent]]|access-date=3 December 2010|date=23 June 2007|first=Paul|last=Newman|location=London}}</ref> Some tournaments allowed players a greater margin for error, with players allowed an unlimited numbers of challenges over the course of a match.<ref name="tind1"/> In other tournaments players received two or three per set.<ref name="tind1"/> On 19 March 2008, the aforementioned organizing bodies announced a uniform system of rules: three unsuccessful challenges per set, with an additional challenge if the set reaches a tiebreak. In an advantage set (a set with no tiebreak) players are allowed three unsuccessful challenges every 12 games. The next scheduled event on the men and women's tour, the [[2008 Sony Ericsson Open]], was the first event to implement these new, standardized rules.<ref>{{cite news|url=http://news.bbc.co.uk/sport1/hi/tennis/7305404.stm|title=Hawk-Eye challenge rules unified|date=19 March 2008|access-date=22 August 2008 | publisher=BBC News}}</ref>

====Replacement of human line judges====
Since 2021 the Australian Open has used Hawk-Eye to call lines in all games.<ref>{{Cite web |title=Australian Open: In a Grand Slam first, all courts will feature electronic line calling |url=https://www.skysports.com/tennis/news/12110/12207194/australian-open-in-a-grand-slam-first-all-courts-will-feature-electronic-line-calling |access-date=2024-09-23 |website=Sky Sports |language=en}}</ref>  The US Open replaced line judges with full electronic line calls in 2022.<ref name="Boyo" /> On 9 October 2024 the [[All-England Club]] announced that electronic line calling would replace human line judges full-time at Wimbledon starting in [[2025 Wimbledon Championships|2025]].<ref>{{Cite web|url=https://www.theguardian.com/sport/2024/oct/09/tennis-wimbledon-abolishes-line-judges-after-147-years-electronic-line-calling|first=Tumaini|last=Carayol|website=The Guardian|title=You cannot be serious? Wimbledon abolishes line judges after 147 years|date=9 October 2024|accessdate=9 October 2024}}</ref>