How FIFA's Goal Line Technology Works

Yesterday, during the France versus Honduras match, at the 2014 FIFA World Cup Brasil we witnessed for the first time the use of FIFA's goal line technology.

In the video clip below you will see how FIFA's goal line technology helped award the goal to Karim Benzema of France as his shot had struck the post and the ball crossed the goal line before the Honduras goalkeeper, Noel Valladares, could pull it back in play.

Despite being aware that goal line technology is in use at the World Cup, Honduras coach (Luis Fernando Suárez) , went on to criticise the officials for awarding the goal during the match.

Perhaps we all need to understand how it works in order to appreciate it's accuracy and convinience.

Frank Lampard's Disallowed Goal

During the 2010 FIFA World Cup hosted in South Africa, England eventually lost 4 - 1 to Germany; but when the score was 2 - 1 in favour of Germany, Frank Lampard (England) scored what television replays proved to be a legitimate goal that would have brought England level with Germany at 2 - 2.

The referee disallowed the goal.

This re-ignited the calls for FIFA to introduce goal line technology, especially for national team competitions.

Since the 2010 FIFA World Cup we have witnessed UEFA introducing goal line assistant referees in the UEFA Champions League as well as FIFA testing the same idea at junior national team competitions.

Although the Additional Assistant Referees (AAR) system has assisted in reducing the amount of errors regarding awarding of goals which a referee would not have clear visibility of, the system is still prone to human error.

Enter GoalControl

To many people's surprise, in 2013 FIFA decided to award the license for goal line technology to little known German company GoalControl GmbH from Würselen.

The system was first used in the 2013 FIFA Confederations Cup.

This decision, seemed to snub well established British company, Hawk-Eye, which already supplies similar ball tracking technology for sports such as tennis and cricket.

The company's system, GoalControl-4D, is said to make use of 14 high speed cameras directed at both goal mouth areas.

How GoalCotrol-4D Works

The system works with 7 high speed cameras located around the stadium pointing at each goal mouth area (total of 14 cameras). These cameras are located around the stadium, e.g. on the rooftop.

The cameras then track the ball but eliminate images of players, refereees and another objects not required to decide whether the ball crossed the goal line or not. They are connected to an image processing computer to assist with this.

Once all other irrelevant objects are eliminated from the image, the company says that:

"The remaining object is the ball and the system knows its three dimensional x-, y- and z-position with a precision of a few millimeters in the coordinate system of the pitch. When the ball passes the goal line, the system sends a vibration- and optical signal to the officals´watches. Of course, all camera images of such goal event, and also of all near-goal events, are stored and can be replayed anytime."

In addition to the goal line technology system, the company offers a GoalControl Replay system.

In some cases, like the example of Benzema's goal against Honduras, television cameras are not able to conclusively show that the whole of the ball crossed the goal line thus the replay system delivers in real time the "visual proof of the goal event".

This is for the benefit of the spectators and the teams alike to have no doubt as to the decision made.

Cover Image Credit: Calcio Streaming

Images Credit: GoalControl

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