With Wembley set to host not only Belgium this weekend but also one of Fifa’s preferred ball tracking systems, Hawk-Eye, we thought it would be interesting to take a look at the systems that are hoping to become standard across major tournaments and leagues around the world.

 

Hawk-Eye

Hawk-Eye is the name of both the system and company that uses ball tracking software in order to predict the trajectory of a ball. The system relies on a number of cameras that are used to track the path of the ball therefore creating a 3D image which can be used to show the exact position of the ball. In tennis for example it is used to show whether the ball has landed in or not.

 

More specifically the system will use six cameras facing the goal at each end of the stadium in order to triangulate the trajectory of the ball and determine whether the ball has crossed the line. Each camera records the action in 106fps which is much greater than commercial TV. Indeed the higher frames per second should prevent instances of where a missing frame on a television replay prevents us from being able to tell whether the ball has in fact cross the line. When determining the position of the ball Hawk-Eye uses two inputs. It takes information of the location of the ball from the six cameras along with the speed of the ball. This information is then processed using Hawk-Eye’s software. The most important aspect of Hawk-Eye’s system, however, is the speed with which it works. Fifa has stipulated that information must be passed to the referee in under a second . By sending an encrypted radio message to the referee’s watch as soon as the ball has crossed the line Hawk-Eye is able to meet this requirement.

 

GoalRef

More interestingly from a technology perspective is actually the other goal-line technology system that is to be trialled in the Denmark vs Australia game on the same day as the one at Wembley. Developed by the German research and development institute Fraunhofer IIS and going by the slightly less catchy name of GoalRef this alternative to Hawk-Eye uses a chip implanted in the ball itself, along with magnetic fields across the goal to tell whether the ball has crossed the line. Low intensity magnetic fields are created by antennas around the goal area. When the ball crosses the line the chip inside causes a change in the magnetic field. This information is then analysed by a processing unit before the information is sent to the referee. In a demonstration of the technology the signal that the ball has crossed the line was sent in only a tenth of a second, well below the one second demand of Fifa.

 

Which System Will Become the Norm

Fifa is set to make a decision on goal-line technology on 2nd July with both systems expected to be accepted. The Hawk-Eye system is said to cost around £250,000 to be installed in a stadium whereas GoalRef is considerably cheaper with only micro-chipped balls, a magnetic field and a processing unit necessary for implementation. Although in a sport where players are paid hundreds of thousands a week it is unlikely that price will have much of an impact on which system is adopted by the major leagues around the world. A second consideration over which system should be introduced is the experience for the TV audience. Broadcasters have seen the how Hawk-Eye has enhanced the viewing experience of people in both cricket and tennis and will surely been more excited by the video feedback a camera based system provides rather than a micro-chip. Whatever system becomes the standard across the globe it looks like we won’t have to put up with fans’ incessant whining about a disallowed goal for too much longer.

 

Sources

http://www.matrox.com/imaging/en/press/feature/other/hawkeye/

http://www.smh.com.au/articles/2005/01/28/1106850112048.html

 

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