FIFA's goal-line technology simplified

BANGALORE, INDIA: England midfielder Frank Lampard would always look back wryly at the turn of events in the knock-out round against Germany at the 2010 FIFA World Cup.

In what became 'the goal that was not to be', his strike hit the crossbar and ricocheted over the line. Alas, the referee and linesman missed it and it was not awarded a goal!

Now, Lampard can have a sigh of relief, with the International Football Association Board (IFAB) recently approving the use of goal-line technology to aid in referee calls on ball crossing over the goal line and post. Once implemented, the margin of error, after all, would become virtually nil.

"We have decided to use the system at the Club World Cup in Tokyo (in December), at the Confederations Cup (in 2013) and the 2014 World Cup (in Brazil)," FIFA secretary general Jerome Valcke said after the announcement.

On-field referees, in case of tough calls on whether the ball has crossed the goal line or not, can employ two technological aids under this system. According to Valcke, Hawk-Eye and GoalRef are the two methods to be adopted.

Watch FIFA.com's video explaining the technology here: http://bit.ly/NmpPUB.

Here is a look at both the methods.

GoalRef

This method utilizes magnetic field to track the ball and confirm or deny a goal, based on the ball's position and trajectory over the line.

It is a joint Danish-German project, initially pioneered by former FIFA referee Peter Mikelsen. Unlike the previously-considered Cairos system, which required the chip to be inserted in the exact middle of the ball, the electronic probes are attached between the inner ball and the inside of its leather outer lining, writes Martin Lipton on Mirror Football: http://bit.ly/LZUeZs.

Under this method, sensors are installed on the inside of the goalposts and crossbar. They emit electronic waves and as the ball moves across the sensor zones, there will be a change in wavelength effected by the motion.

Immediately, the resultant Doppler effect would be registered by the device and transmitted in less than one-tenth a second to the on-field referee.

It is much cheaper to install than the Hawk-Eye and its mass production is already happening.

Hawk-Eye

If you follow tennis or cricket, you would be familiar with this technology. It is based on optical recognition with cameras, which a Hampshire-based company evolved.

It's a computer system to track the trajectory of the ball and display a record of its most statistically likely path as a moving image. Hawk-Eye systems are based on the principles of triangulation using the visual images and timing data provided by a number of high-speed video cameras located at different locations and angles around the area of play.

In cricket, leg before wicket (LBW) decisions, line, length and speed of the delivery, as well as the batsman's movements can be tracked and determined through this technology.

In tennis, the system normally has ten cameras to capture and process the video feeds by a high-speed video camera and ball tracker. A data store contains a predefined model of the playing area and includes data on the rules of the game.

Both sports were revolutionized after the introduction of the Hawk-Eye. Will football follow suit with the goal-line technology?