Brazil 2014 is the first FIFA World Cup in which the refs had a little technological assistance to help them know whether the ball crossed the goal line.
This year, for the first time, technology made the tough calls at the World Cup in Brazil. And with replay tech, it is actually several types of technology working together.
In the weeks leading up to last year's Confederations Cup, also hosted in Brazil, FIFA granted the German company GoalControl access to install 14 high-speed cameras in each of the stadiums, with seven cameras monitoring each goal line from various points along the upper levels of the stadiums or the roof. The cameras can capture up to 500 frames per second and transmit those images to an image-processing computer via fiber-optic cables.
The computer tracks the 3D coordinates of the ball at all times, and is able to separate the ball from images of players and referees, whether it is on the ground or sailing through the air. The margin of error is plus/minus 1.5 centimeters (about 0.6 inches).
When the ball crosses the line (the entire ball must cross), the computer sends a signal to a wristwatch the referees wear. The watches vibrate and flash the word "goal" within a second of the ball crossing the plane of the goal line. This allows the referees to use the system without stopping the flow of the game—there is no need to go back and watch a replay, as NFL refs and MLB umpires have to do. The systems cost about $250,000 per stadium.
Other sports have been using this kind of tech for years. Following a botched call in the 2010 World Cup, FIFA started testing four different systems. One option was HawkEye, the system used in professional tennis since 2005 and the U.K.'s Premier League 2013–2014 season. Two other systems, Cairos GLT and GoalRef, use magnetism to track the position of the ball. Cairos GLT embeds a sensor in the ball and thin wires underneath the ground in the penalty box, which track the movement of the ball. GoalRef places the sensor in the edge of the goal line. But FIFA went with GoalControl for the world's biggest tournament.
The technology made its World Cup debut 3 minutes into the second half of Sunday's match between France and Honduras, but not without causing confusion. As a French shot ricocheted off the Honduras goalpost, Honduras goalie Noel Valladares fumbled it and pushed it out of bounds. The stadium jumbotrons flashed the replay and the words "no goal," but the wristwatch on referee Sandro Ricci's wrist told a different story. The watch vibrated, signaling that the ball had crossed the line.
Ricci blew his whistle and raised his hand, signaling that it was a goal. Viewers at home and in the stands, as well as the teams, remained confused, as the screens continued to say "no goal." But the confusion subsided, at least for the fans and referees, when it was determined that the system was showing the replay of the shot hitting the post—not that of Valladares fumbling the rebound off the post. These were separate events. The system had accurately ruled that the second event—the ball crossing the line as Valladares attempted to control it—was indeed a goal. France took the 2–0 lead in a game it eventually won 3–0.