Latest news with #linecall
Telegraph
4 days ago
- Science
- Telegraph
The science that shows Hawk-Eye isn't as accurate as it seems
At the Madrid Masters in April, top seed Alexander Zverev was given a warning for unsportsmanlike behaviour. His offence was to take out his phone and snap a picture of a clear ball mark in the clay which was more than an inch outside the line. The electronic system Hawk-Eye had called it in, and he lost the point. 'The ball is not just a little bit – a millimetre – in or out, it was like four, five centimetres,' the German said in a post-match press conference. World No 21 Donna Vekic branded the line call as 'insanity'. It is one of several recent cases in which players have questioned the accuracy of Hawk-Eye, which this year replaced line judges at Wimbledon after 147 years. World No 1 Aryna Sabalenka also took pictures of a disputed ball mark during her quarter-final victory over Elise Mertens at the Stuttgart Open in April. At this year's Wimbledon, Emma Raducanu said it was 'disappointing' that the 'calls can be so wrong' while Jack Draper argued after his second-round defeat: 'I don't think it's 100 per cent accurate.' Scientific experts increasingly believe the players have a point. In 2009, Professor Harry Collins of the University of Cardiff wrote a paper highlighting the problems with Hawk-Eye, and he believes little has changed. 'Hawk-Eye is useful for big errors but for very small errors everybody knows that the thing just cannot be exact,' he said. How Hawk-Eye really works Tennis viewers may not realise that Hawk-Eye is not a true video-replay of the shot, but a virtual reality simulation based on the speed and trajectory of the ball. It relies on a network of 10 high-speed cameras which capture the ball from different angles at a fast frame rate, feeding the movement into a computer algorithm which then triangulates the position, creating a reconstructed image of the flight path. It means that the final line call is not where the ball landed, but where it 'should' have landed based on how it was moving. The distinction is important. Even Hawk-Eye Innovations, which developed the technology, admits that the system has a mean error rating of 2.2mm, which may not sound much, but can have big implications for players hitting shots with pinpoint accuracy. Critics also point out that if 2.2mm is the mean error rate then, on occasions, it must be far less accurate than that. The company has never released information on just how inaccurate Hawk-Eye can be, but if standard calculations are used to estimate the expected distribution of errors, it suggests accuracy could be out by more than 5mm in one in 20 occasions, and more than 7mm in one in 100 shots. It is also unknown if the accuracy rate falls for certain types of shots – such as killer forehands or super-fast serves, where the camera frame rate struggles to keep up with balls flying at 150mph. Likewise, it is unclear how well the system accounts for spin which can cause a ball to suddenly drop like a stone in mid-air or swerve unexpectedly to the left or right. The system is also known to be impacted by both sunlight, shadow and floodlights as well as wind which can cause the cameras to wobble. The lines on the tennis court can sometimes be obscured by the players themselves. In the Zverev example in Madrid, it was speculated that the cameras had misread a clay grooming line to the left of the court, believing the mark to be the real sideline. Professor Collins added: 'A painted line on a tennis court cannot be a sharp edge, and when a tennis ball bounces it distorts, and you have a hairy, distorted tennis ball next to the ragged edge of a line, so it can't be exact. 'The way it ought to work is when the ball is close to the line, within a couple of millimetres, then there should be a let or the umpire's decisions should count. 'It's dangerous to rely on this technology alone because it is misleading the public into thinking that virtual reality is real reality.' Electronic line calling has been used instead of line judges at the US Open and Australian Open since 2021 and the International Tennis Federation told The Telegraph that it has been 'rigorously assessed' against a wide range of criteria including accuracy, reliability, suitability and practicality. But there have been numerous incidents when players and viewers claim the technology has gone wrong. A glitch in the system During a first round match of last year's Cincinnati Open, American Brandon Nakashima hit out a forehand which should have seen him facing a break point against compatriot Taylor Fritz. But the electronic line call stayed silent until later on in the point when it finally corrected the error, disrupting the game and forcing a replay. At the 2024 Miami Open, during the match between Australian Daria Kasatkina and Romania's Sorana Cirstea, a ball that was clearly outside the line was called in, with Hawk-Eye footage showing it moving in the wrong direction. Defending champion Carlos Alcaraz was overheard complaining about some of the calls during his third round win at Wimbledon this year. Last year, a paper by Nigerian researchers warned that there can be gaps in data captured leading to 'less accurate predictions or incomplete information about the ball's path' and said the system could be stymied by 'unorthodox deliveries' or 'poor calibration of equipment'. Fans of electronic line calling claim that even with the errors Hawk-Eye is still more accurate than line judges, and argue that contested shots often look different on TV because of the 60 frames per second rate of broadcast cameras, which causes motion blur. In comparison, testing of the technology is done using cameras of 1000 frames per second. A question of trust All England Club chair Debbie Jevans argues that players have been asking for electronic line calling for years because they thought it was more accurate, while Tim Henman has branded this year's Wimbledon complaints as 'garbage' claiming Hawk-Eye was '100 per cent accurate'. However, critics say that if tournaments continue to use the technology, it should be made clear that the Hawk-Eye replays are not true footage and that they can be prone to errors. Professor Robert Evans, of Cardiff University, who co-authored the 2008 Hawk-Eye paper with Professor Collins, said: 'It was more the way it was presented as completely accurate, with no error and no mistakes, that was the focus of our critique. 'Viewers should be told they are not watching a replay of the real event.' The Telegraph contacted Hawk-Eye Innovations on three occasions to learn more about testing, accuracy and error distribution but did not receive a reply.
The Independent
08-07-2025
- Sport
- The Independent
Wimbledon suffers another tech malfunction as ‘fault' is called mid rally
Wimbledon's latest electronic line call blunder was due to the movement of a ball boy. The faltering system was thrust back into the spotlight on Tuesday afternoon following an embarrassing malfunction during Taylor Fritz's four-set quarter-final victory over Karen Khachanov. Swedish umpire Louise Azemar-Engzell called 'stop' in the opening game of the fourth set on Court One when 'fault' was incorrectly announced after a Fritz forehand landed well inside the baseline. The cry of 'fault', rather than 'out', and positioning of the ball suggested the technology was still tracking Fritz's serve as opposed to a rally. Tournament organisers verified that theory, explaining the system had failed to reset because the ball from Fritz's first serve was still being retrieved when he started lining up his second. Neither player showed much reaction as match official Azemar-Engzell ordered the point be replayed. Fritz led 2-1 on sets at that stage before completing a 6-3 6-4 1-6 7-6 (4) victory in two hours and 36 minutes. 'The player's service motion began while the BBG (ball boy or girl) was still crossing the net and therefore the system didn't recognise the start of the point,' read a statement from the All England Club. 'As such the chair umpire instructed the point be replayed.' Tournament organisers said on Sunday they were confident of avoiding further issues with the technology after a major error in Sonay Kartal's fourth-round defeat to Anastasia Pavlyuchenkova in the women's draw. On that occasion, the new system failed to call 'out' when a shot by Kartal bounced well behind the baseline. Had the call been correct, Pavlyuchenkova would have taken a 5-4 lead in the first set. Umpire Nico Helwerth instead ruled the point should be replayed, with Kartal going on to win the game. However, a major scandal was avoided as the Russian, who accused the official of home bias, battled back to progress. After an investigation, organisers admitted the technology was turned off in error on a section of the court. Britain's leading duo Jack Draper and Emma Raducanu have each complained about the accuracy of the system, which is widely used on the tour but has only just been introduced in SW19. The latest incident is another embarrassment for the Championships amid controversy over the removal of line judges.
The Independent
07-07-2025
- Sport
- The Independent
Wimbledon umpire at centre of line-call controversy has ‘rest day' on Monday
The umpire who officiated the fourth-round match that featured a controversial line call is having a 'rest day' on Monday, according to the All England Club 's chief executive. Nico Helwerth, who was the chair umpire for the fourth round match between Sonay Kartal and Anastasia Pavlyuchenkova, was at the centre of the controversy after an operator error meant that the new electronic line calling technology was deactivated for one game. Kartal sent a shot long when game point down at 4-4, though this was not detected and the system instead made automated calls to "stop". And Helwerth then opted to replay the point, which Kartal then won. He was criticised by Pavlyuchenkova, who said at the time that he 'took the game away from me', later adding that 'the chair umpire should be able to take the initiative'. When asked about Helwerth's absence from the match list for Monday 7 July, All England Club chief executive Sally Bolton said that the competition has 'rotation of our umpires regularly', reports the BBC. 'A little bit like the players, the umpires also need rest days throughout the tournament. So he's having a rest day today. "He's fine. Look, it's really important to say that the umpire followed the protocols in place. He did what he needed to do on court and acted entirely correctly,' added Bolton. In this case, the rulebook states that if the electronic line-calling system is unable to make the call, then the chair umpire should make it. If they are unable to determine whether the ball was in or out, the point should be replayed. The new technology was introduced at this year's tournament, and is an enhanced version of the previous Hawk-Eye system. In a statement on the new system, a Wimbledon spokesperson said: 'We continue to have full confidence in the accuracy of the ball-tracking technology. The live ELC system relies on the Hawk-Eye operators, the review official and the technology to work in harmony. This did not happen. "In this instance there was a human error and as a consequence we have fully reviewed our processes and made the appropriate changes."
