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The Coming Revolution in Sport? I f you’ve been watching the cricket or tennis on TV this summer, you’ll no doubt have seen (and heard of) Hawk-Eye. Just how does this allseeing, all-knowing electronic “eye” do its thing? For those who have been too absorbed in the 20th movie repeats of the summer to watch live sport, perhaps a word or two of explanation: HawkEye is an electronic umpire, able to tell (for example) whether a Brett Lee screamer would have hit the stumps had it not hit the pads of a hapless batsman. Or whether a Roger Federer www.siliconchip.com.au 190km/h serve did clip the line, regardless of the fact that the linesman called it out. Hawk-Eye is of course capable of a whole lot more, as we will shortly see – but you get the picture. by Ross Tester It is the brainchild of Dr Paul Hawkins, a 29-year-old PhD who developed the unique system for his employer, Roke Manor Research (itself a division of Siemens), in Romsey, Hampshire, England. In a nutshell, Hawkins took the extensive research which went into Roke’s military tracking system (the single-camera RAPiD system, a model based tracking system which was born out of developments in civil robotics) and applied it to the 3-D, multi-camera world of tracking a ball in flight. Interestingly, Roke developed the military tracking system to track missile trajectories and therefore targets during the Gulf War. Due to Hawkins’ interest in cricket (he’s a social player), Hawk-Eye was March 2004  7 In the cricket version, Hawk-Eye uses six fixed video cameras placed around the edge of the arena. The images are electronically compared and analysed to determine the ball’s location at any instant. A somewhat similar arrangement is used for tennis. first developed for the cricket pitch. Since then, it has been developed for tennis, baseball and even snooker/ pool. The name, by the way, is Paul Hawkins’ father’s nickname – and it also very aptly sums up the system itself! Hawk-Eye was launched in 2001 and in that year won the Royal Television Society award for Technical Innovation. Why use Hawk-Eye? There are few more frustrating things to a sportsman or woman (and therefore to millions of fans) than a “bad call” by a judge, umpire or other official. Worse is when that bad call has a major influence on the outcome of the game. The problem is, of course, that many of the decisions officials have to make are for events which last no longer than the blink of an eye. In many respects, it’s a wonder that officials do manage to get it right most of the time. And believe it or not, they do. Take cricket, for example. A lot of umpiring decisions are relatively easy: that delicious sound (for a fast bowler!) of leather crashing into the stumps and the sight of the bails flying high in the air! Catches are usually fairly simple, too – although umpires these days may call on the “third umpire” with the benefit of slow-motion replays if there is any doubt, either if a ball has carried or if it even hit the bat. Likewise, run-out decisions are often assisted by electronic means if the umpire is in any doubt. Somewhat surprisingly, about the only ruling that isn’t currently electronically assisted is LBW (leg before wicket). We say surprisingly because it is in LBWs that electronic assistance is arguably – with Hawk-Eye – now the most certain. And it is LBW decisions that are usually the most controversial, because they involve a “what if” judgement, as distinct from an event judgement. The umpire must decide not only if the ball was travelling at such an angle and height that it would have hit the stumps were the pads not hit first; he must also judge that the ball also ptched inside the line of leg stump. And if the batsman had advanced down the wicket, it becomes that much harder. Now put the speed of the ball into the equation: perhaps 150km/h or so and you’ll see why errors do occur. In fact, in the first season that Hawk-Eye was used as an aid to commentators, it indicated that 13 out of 21 LBW decisions were wrong – both ways. Although initially designed to be used in television coverage, the system could also be used by the umpires to bring a measure of consistency into the decisions being made during a match. The final decision on LBW will always be with the umpire but Hawk-Eye would add significant value by making precise measurements which the human finds very difficult. Perhaps we are getting ahead of ourselves. Hawk-Eye has not (yet!) been used by umpires to assist in their decisions as to whether or not a batsman is out. However, that day must surely come as TV networks not only bring the umpire’s calls into question with endless slow-motion replays – now with Hawk-Eye simulations they can prove, with virtually no error, whether the umpire was correct or not. It will arguably be the public who force the issue eventually, as there is little call from umpires to have the extra technology at their fingertips. This is one of the features of HawkEye – its data can be almost instantly transmitted to the man in the middle to help with difficult decisions. Using a small hand-held computer or PDA, the umpire can tell straight away whether a batsman should have been out. Just some of Hawk-Eye’s seemingly endless possibilities for giving the viewer added enjoyment in a match. The first screen shows the ball trajectory from the moment it left the bowler’s hand; the second the point of impact with the bat (or body!) 8  Silicon Chip www.siliconchip.com.au Similarly, tennis umpires could have the technology at their disposal for dubious line calls. How many matches have swung one way or the other following an obvious (to the TV viewer!) mistake. They break the player’s concentration at the very least. Not everyone agrees . . . There has been some reaction from players – both positive and negative, as you might expect. A batsman who has been on the wrong end of too many LBWs is much more likely to favour the system than one who has “gotten away with murder” out in the middle. Even former cricket “greats” are divided. A newspaper column written by the former fast bowler Dennis Lillee dismissed Hawk-Eye almost out of hand. But Paul Hawkins claimed that article was “probably the most ill-informed ever written about the system . . .” Dickie Bird, the former UK umpire, was once a critic but is now one of Hawk-Eye’s biggest supporters. He originally claimed that it would kill the game but now advocates its use. “Surely the need is to alleviate error,” he said. Similarly, tennis authorities such as the ITF have not yet given Hawk-Eye their glowing endorsement, citing cost as one reason. However, John McEnroe, commentating during the Australian Open finals, glowingly praised Hawk-Eye and wished it was available to the umpire after a couple of obvious errors in line calls. He even joked with the other commentators when one remarked that it would have put an end to his now famous (infamous?) “You cannot be serious!” arguments with tennis umpires and referees. Another claim from sports administrators is that Hawk-Eye could be seen to undermine the authority (and skill levels?) of the officials around the court. They are not unique: most sports over the years have been reluctant to adopt new technology to assist their officials. Having seen this first-hand in other sports, where electronics is allowed to overrule course judges, all I can say is bring it on . . . How Hawk-Eye works. The Hawk-Eye system tracks the ball from the moment it leaves the bowler’s www.siliconchip.com.au Hawk-Eye can superimpose the batsman in typical stance to show just where the balls faced have actually ended up. It’s valuable for later review of performance and also for coaching. hand until it stops (or of course from the tennis racket). It does this using both image analysis and radar technology. If required, it then projects the flight of the ball after it has stopped, by extrapolation. Using dedicated cameras and specialist image processing software, the position of the ball can be located extremely accurately in three dimensions. On the cricket ground, six fixed and synchronised “JAI” monochrome cameras, with a 120Hz frame rate, are placed around the perimeter of the playing field at specific points – two are 30° off each end of the wicket while two side cameras look directly across their respective stumps. These synchronised cameras track the ball’s entire trajectory – at intervals of 1/120th of a second – from the moment it leaves the bowler’s hand until it stops. The six cameras are gen-locked into two sets of three cameras, each set being captured by a Matrox Meteor-II/ Multi-Channel frame grabber and the Matrox Imaging Library (MIL-Lite) software. The resulting images are processed into a 3D image by the Hawk-Eye system which then calculates – in a split second – where the ball pitched, the extent of its lateral movement in the air and off the wicket, its velocity and bounce and – if applicable – exactly where it contacted the batsman’s pad. Positional accuracy is claimed to be no worse than five millimetres, with some references giving Hawk-Eye an accuracy of 1-2mm (assuming fixed camera positions). The future path of the ball is also extrapolated by fitting the trajectory of the ball into a parametric model, thereby determining whether or not the ball would have carried on to hit the stumps, bounce over, or go past the wicket. Hawk-Eye then uses a Matrox Orion frame grabber to overlay a graphical representation of this trajectory onto a video image. This image is then encoded and transmitted to a video bank, ready to be virtually instantly accessed by television production staff and commentators. Tennis uses a similar process to cricket – Hawk-Eye is most useful for determining when a ball is in or out. But for the TV audiences, it has been extensively used to show the action of, for example, a serve and just how far the balls swing. A market is also seen for Hawk-Eye in coaching – stroke analysis is easy when you can show exactly what the ball does. The South Africans have been using Hawk-Eye for this purpose and last October, the system was installed at the English Academy at Loughborough College, near Nottingham. Not only cricket and tennis In partnership with Sunset + Vine, the television production company, Roke Manor Research has established Hawk-Eye Innovations Ltd, an organization entirely dedicated to the development of similar technologies for wider sporting activities and applications. Dr Hawkins is its CEO. So far, Hawk-Eye has been adapted to baseball – primarily to determine strikes and balls – and is also available for football (particularly gridiron) and even snooker/billiards/pool! SC Acknowledgement: Much of the information and text for this article originally came from Roke Manor Research and Matrox. Hawk-Eye screen diagrams courtesy of Channel 9, Sydney. March 2004  9