Freeze frame images of a goal in progress

Sports Tech: Goal-line technology

Goal line technology is set to put an end to the age-old argument about the decisions made by football referees.

Germany may have been the beneficiaries of the absence of goal-line technology at the last World Cup, but a German company will provide the systems for the next one.

Three years after Frank Lampard's infamous shot for England against Germany that crossed the line but was not awarded as a goal, world football governing body Fifa has appointed GoalControl to provide a system for the Confederations Cup in Brazil in June and at the World Cup 2014.

The system, GoalControl-4D, uses 14 high-speed cameras located around the pitch and directed at both goals. It is the simplest and most effective of the four systems currently licensed and will cost around £170,000 per stadium to install and a further £2,800 per match to operate.

The company was selected ahead of the three other Fifa-licensed technology providers, including UK-based Hawk-Eye Innovations who were later selected by the English Premer League.

The Hawk-Eye system uses seven cameras per goal. The most common location is on the roof of the stadium, however there is a great deal of flexibility in the positions. The images from each of the cameras are processed to find the ball and also identify areas which are definitely not the ball. The system is able to find the ball if only a small part of it is visible. It can work with any pattern and specific vision processing techniques are used to identify each ball. The system is unaffected by mud on the ball or adverse weather conditions.

Control software combines the information from all cameras and is able to track the ball within the goal area. As soon as the system detects that the ball has crossed the goal line it sends a signal to the official's watch, which has been developed by industry leaders Adeunis. It is also possible to provide a "near-miss" signal so the referee receives confirmation that the ball did not cross the line.

All-seeing cameras

The system is able to locate the ball even if it is only picked up by two of the seven cameras. Hawk-Eye claims there has never been a goal line incident where the ball would not have been seen by at least one of the cameras.

It uses a dedicated high-speed camera that can remove the players from the image to ensure the ball is fully visible. This provides the definitive replay for broadcast and digital media.

There are many similarities between Hawk-Eye and Fifa's approved system. The GoalControl-4D system also works with seven high-speed cameras per goal, all located around the stadium roof.

The cameras are connected to a powerful image-processing computer system, which tracks the movement of all objects on the pitch and filters out the players, referee and all other objects. All that's left is the ball and the system knows its three dimensional x-, y- and z-position to within 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 officials' watches. All camera images of every event are stored and can be replayed anytime.

"While all four companies had previously met the stringent technical requirements of the Fifa quality programme, the final decision was based on criteria relating to the tournaments in Brazil, including ability to adapt to local conditions and the compatibility of each system in relation to Fifa match operations," a Fifa spokesperson says.

"The respective bids were also judged on cost and project management factors such as staffing and time schedules. The use of GoalControl-4D in Brazil is subject to a final installation test at each stadium."

It will be the second time a Fifa tournament has used goal-line technology after two other systems, including Hawk-Eye, were used successfully at the Club World Cup in Japan in December.

Premier technology

Hawk-Eye's camera-based system will be in place at Premier League grounds and Wembley Stadium from next season.

Hawk-Eye, which was sold to technology giant Sony two years ago, provides systems for tennis and cricket. The Premier League provided seed money to help the company develop a goal-line technology system back in 2007, but there was no longer a formal relationship with the company.

Many supporters and pundits decry the technology, saying that it heralds the start of a slippery slope towards a stop-start game where every decision is analysed. But Arsenal manager Arsene Wenger has welcomed the Hawk-Eye system, claiming it doesn't go far enough.

Wenger insists football must embrace more new technology innovations to help eradicate any perceived injustice, such as those in the recent Champions League semi-finals where Borussia Dortmund netted controversial late goals to knock out Malaga.

"When you look at the level of refereeing that you have seen again in Europe, it is absolutely disastrous what happened," he says. "The major decisions that have gone wrong in the Champions League, football cannot accept that. When you have four players offside and nobody sees it, how can that happen? In the same action, another player is offside and scores a goal, and we defend that? It is not defendable.

"I would at least like to see that in major decisions, where you go to a semi-final of the Champions League or not, the referee has the opportunity to check if the goal is valid or not."

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