Augmented Reality Goal System
In response to criticisms revolving around the game of football (or soccer as it is known inside the US), specifically relating to whether or not the referee correctly rules a football is across the goal line or not, when it has come to rest on the painted line itself. Fifa, the world football governing body has relented on a years-long determination to rely solely on human decision making to referee matches.
The IFAB investigated the possible use of technical aids after several incorrect rulings including the disallowed goal for England in the game against Germany in the 2010 World Cup. Eight goal-line technology systems were initially tested for the International Football Association Board in November 2011 and December 2011.
The evaluation criteria were compiled by the Swiss Federal Laboratories for Materials Science and Technology. Their strict measurements were in line with the high standard of training expected from human referees, and demanded that no changes to the ball itself be made, and that no sensitive equipment was in front of the goal where it could be smashed by the kicks of over-enthusiastic players.
In its meeting of Thursday 5th July 2012 the International Football Association Board (IFAB), the body which determines the laws of the game, approved two goal-line machine vision systems, called GoalRef and Hawk-Eye respectively. Both will be installed in each world-class stadium around the world, to offer independent verification of each other's findings. The human referee is still involved, and makes their own decision. The majority out of the three decisions is what counts. So if the two systems disagree, the human referee calls it. If the two systems agree, but disagree with the referee, it is their decision which carries.
The GoalRef system was developed by researchers from the Fraunhofer Institute for Integrated Circuits IIS. "The technology works in a similar way to that of the theft protection of a department store," explained René Dünkler, spokesman of the GoalRef project. Ten antennae behind the goalpost and crossbar create and monitor a weak magnetic field. As soon as the ball nears the goal-line the field is influenced by thin spools regularly found in normal footballs. A processor is then able to determine by means of the antenna signal, whether the ball fully crossed the goal-line or not.
"GoalRef is a bit like an invisible curtain which hangs behind the crossbar and the goal-line. As soon as the ball fully passes through this "curtain", it is recognised as a goal," says Ingmar Bretz, project head of GoalRef. The system then automatically sends this information in real time via encoded radio signals to the referees whose special wrist watches display the result visually, calling their attention to their wrists by vibrating against them. The same data is sent to the commentator's box and anywhere else it needs to go.
The Hawk-eye system, on the other hand, has no on-pitch installation. Rather, numerous high frame rate cameras are placed around the stadium, each focussed on one or the other goal mouths, building up a composite picture of the goal in three dimensions, by combining multiple streams. When the ball nears the goal – but before it has crossed, these cameras start recording automatically, so that should their system's decision be questioned, a playback is possible. Recording continues until the ball leaves the goal area, at which point, it is automatically halted and filed.
The data from the cameras is, predictably, fed into a central processing unit that analyses the position of the ball relative to that of the goal line. If the system recognises that the ball has crossed the goal line, it relays that information in less than one second to a device on the referee's wrist. Their other wrist, else the referee's arms are going to get crowded. The two systems are presently not compatible with each other's wrist devices.