The wires in the ball are small and robust enough to survive the impact of being kicked around for 90 minutes, and they weigh so little that a GoalRef ball is indistinguishable from a regular one. "If you don't know that it's a special ball, you cannot decide whether it's normal or one with the special technology," says Rene Duenkler, a scientist with GoalRef. The ball is even approved by FIFA for use in games.

The distinction between these two technologies is that one is camera-based and one is not. And that difference could be the deciding factor. Unlike tennis, where there is almost never any thing or person obstructing the line of sight between the cameras and the ball, soccer presents unique challenges—especially during free kicks and corner kicks. In such situations, 10 players might be close to the goal, making it harder for cameras to unambiguously record when the ball passes the line. Hawkeye declined to comment on its technology, as it is still in the testing phase, but the company's Web site notes that it is dealing with a way to compensate for the problem by using multiple camera angles.

Not everyone is keen on goal line technology. Michel Platini, head of the Union of European Football Associations (EUFA), worried that introduction of this technology would begin a slippery slope toward more intrusions to the game, and he stood staunchly opposed to the technology. So even if UEFA is not on board, FIFA is, and the next international soccer stage will feature a new prop—a technology that will help enforce the line between winners and losers.

6 Comments

1. 1. promytius 11:22 AM 7/26/12

   'Professional' sports are not science. They are simply money-making machines for the ultra-rich. I really don't care what they use to decide anything in sports, because it is all completely irrelevant to reality. It's a stupid game (and you may substitute ANY 'professional' sport) played by millionaires for other millionaires' profits, so I suggest that instead of figuring out how to score the stupid ball, why not just auction the goals off? Money talks. Or, they could just admit it's all about money and get on with it, but there is no USEFUL science in monitoring a goal, a plate, a line on the ground, or in the air. Self-indulgence at its most avaricious, too silly for SA to even comment on, never mind feature an article.

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2. 2. Bora Zivkovic 01:24 PM 7/26/12

   Interesting approaches. As I started reading this article, I thought to myself I'd use LED diodes emitting infrared light beams, positioned all along the top bar, beaming down to an array of receivers connected to the computer. When the ball breaks any one of those beams, the receiver detects the loss of infrared light and notifies the computer which emits a loud sound.
   
   This is what I used to do in my own research (and built the whole system from scratch, using the oh-so-wonderful Dremmel tool). But then I thought at the false positives I sometimes got and realized those would be even worse in soccer - the system is dumb, and would not be able to differentiate between the ball crossing the line and the goalie (or any other player, or a bird, or clump of dirt) crossing the line.
   
   So I really like the magnetic ball crossing the magnetic field system. It is simple, robust, and gives a clear yes-or-no answer. The multi-camera system appears to be too complex, thus more prone to subtle errors.
   
   Also, while it must have felt good for @promytius to vent here, I did not see this article to be about sociology, economics or politics of sport. His comments, being OT, could potentially be removed according to our commenting rules.

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3. 3. jandone 01:46 PM 7/26/12

   Scoring used to be so easy. If your ball bounces back, it meand you did not deserve that goal. There is a reason they put the net there to catch scored goals.

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4. 4. verhappy 03:16 PM 7/26/12

   Picking up from Bora, I wonder why a simple 5 camera system installed into the goal posts wouldn't work? With the size of security cameras and the like, I don't see a reason that the cameras couldn't be installed as follows:
   
   One recessed into the bottom middle of the cross bar with a fish eye lense--if the ball crosses the line you would see dark between the line and the ball. This one would be covered with a resilient plastic protector to blend it into the goal post;
   Two in each upper corner of the net where they would need minimal recessing since the ball could not touch the deepest corner;
   Two just recessed just a metre or so above the ground in the same way the cross bar was. With these five camera angles on each net it should be obvious whether the ball crosses the plane of the net.
   
   For insurance, a slightly reflective strip or bright colour could be placed on the inside edge of the goal posts so that if the ball is in the air the cameras could pick up from comparison whether it has crossed the line. The magnetic field sounds interesting, but I wonder about false negative should there ever be a malfunction in the wire within the ball? How would they be able to ensure the ball's wire is operational at all times during the game?

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5. 5. hb 03:43 PM 7/26/12

   In both matches mentioned, TV viewers (including soccer officials not involved in the game) could clearly see that the ball had crossed the goal line. In a controversial situation all it would take is for the attacking team to be able to request a review, much as tennis players can demand slo-mo replays of questionable calls. Play would only need to be halted long enough for communication between the referee and an extra official in the TV booth; that official would then make the final decision based on evidence available to every TV viewer. Misuse of the right to request a review should simply draw yellow cards.

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6. 6. jackvandijk 04:41 PM 8/9/12

   voetbal is futbal, no electronics. if the referee makes an error, that is part of the game.

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