For years, international football association FIFA have heavily resisted technology's influence in soccer, almost comically arguing that bad refereeing decisions are all part of the excitement of the game. FIFA president Sepp Blatter has described goal-line technology as "only 95 percent accurate", though even that level of accuracy – when compared to a human eye, often tens of metres away – is surely a vast improvement?
For technologists, even if this disputable 95 percent figure was to be believed, bridging that 5 percent gap was never a sizeable task. Though in 2008 following that statement, the FIFA president put the implementation of such technology on ice – permanently.
Predictably, subsequently further controversial decisions ensued, though in relatively low-key matches not on the international stage, and in March 2010 an election was held between eight of the founding bodies of soccer – voting 6-2 in favor of permanently ditching the technology, the two dissenters being England and Scotland.
In June that year at the 2010 FIFA World Cup the tide was about to turn, when hundreds of millions of fans across 241 separate countries saw England's Frank Lampard score a goal – the ball clearly over a metre across the line – against Germany, which was disallowed due to human error by the referee. Scoring or missing was a turning point in the 2-1 game, which ended as a 4-1 loss for England. The entire country, quickly followed by immense global support (perhaps bar Germany!), put huge pressure on FIFA, and shortly after Blatter announced that the goal-line technology consideration would be re-opened.
The tech contenders
In 2011 FIFA began internal trials with 10 companies' goal-line technology systems, and by 2012 they whittled this down to two potential candidates: Goal Ref, utilizing a passive "chip-in-ball" and a magnetic field to detect its whereabouts; and Hawk-Eye, utilizing a series of high-resolution cameras and triangulation algorithms.
Both have a very high, though interestingly unpublished, accuracy percentage, but neither could claim 100 percent accuracy as both are fallible to some degree.
A technology based on electromagnetic fields, which is being used at the 2014 World Cup, would be susceptible to interference, though unlikely in the environment; an unscrupulous party could theoretically interfere with its accuracy.
The high-speed-camera-based system, you could argue, is less vulnerable to outside interference, though is reliant on installation accuracy and calibration, having rigorously proven the calculations used to derive the decision.
Additionally, in the 2014 World Cup referees are wearing smartwatches as part of a GoalControl-4D system to alert them to goal-line technology cameras detecting goals. So far in the competition goal-line technology has already caused a share of confusion and controversy in the match between France and Honduras. This wasn't a case of the technology malfunctioning, but the public weren't prepared that the GoalControl system would also show instances where a goal was not scored before the instance where a goal was scored if the ball almost crossed the line multiple times.
Both systems also can't consider the change in shape of a ball when it bounces, for example. The Hawk-Eye system, prior to soccer, has long been employed in snooker (similar to billiards), cricket, and tennis. Bounce distortion in soccer, given we're concerned with it passing a line, not falling short of it, isn't relevant – in tennis however this can be contentious; during the 2008 Wimbledon final, a ball that appeared out was cited as "in" by Hawk-Eye by a single millimeter.
Interestingly, despite no percentage claims of accuracy of the technology, a 3.6 mm error margin is advertised by Hawk-Eye. Whilst this seems minute, it's easy to see why the technology claiming it's "in" by 1 mm becomes disputable. Cricket saw a similar point of contention in 2012, where a Leg Before Wicket (LBW) foul was called despite it visually appearing the ball would have sailed over the stumps, which would negate the call.
Soccer has attempted to address the shortfalls of the technology – well, more the opportunity for it to be disputed – by moving away from the "video replay" style of the other implementations completely with the use of a 3D reproduction of the controversial incident.
Whilst this has the advantage of giving an "undisputable" decision, people are naturally wary of any visual that disagrees with what they "saw" with their own eyes – though optical illusions and magic tricks should easily counter how fallible the human eye is to misinterpretation.
The sporting world is truly opening up to the embedded computing industry and is more accepting of new technologies than ever before. Last month I discussed the increasing sports medicine usage of embedded; now I'm sure I've got you thinking about how embedded technology could improve your own favorite sport. Perhaps lasers displaying shot distances and speeds on the pitch, intelligent sporting equipment visually flagging illegal usage – the possibilities are endless!