I have been watching way, way too much tennis for the last week -- the US Open of course. I don't follow tennis except to watch the big tournaments and then I get addicted. Seeing these top-notch athletes putting it all on the line, with just themselves to perform is pretty compelling. Sure, there is a lot of pressure on a professional golfer with only himself to rely on, but he is not running over three miles, often for over 4 hours. Even if you are not a big tennis fan, you gotta admire the players.
Anyway, in the course of watching all this tennis I realized that I had no idea how the technology resolving disputed line calls worked. Sure, it is very impressive within seconds to see exactly where the ball landed (and I do mean exactly,) but how in the hell do they do it. It's not smoke and mirrors, but close. It is the "Hawk-Eye system, which is explained in this Wikipedia article. An excerpt follows:
All 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.[5] For tennis there are ten cameras. The system rapidly processes the video feeds by a high-speed camera and ball tracker. A data store contains a predefined model of the playing area and includes data on the rules of the game.
In each frame sent from each camera, the system identifies the group of pixels which corresponds to the image of the ball. It then calculates for each frame the 3D position of the ball by comparing its position on at least two of the physically separate cameras at the same instant in time. A succession of frames builds up a record of the path along which the ball has travelled. It also "predicts" the future flight path of the ball and where it will interact with any of the playing area features already programmed into the database. The system can also interpret these interactions to decide infringements of the rules of the game.[5]
The system generates a graphic image of the ball path and playing area, which means that information can be provided to judges, television viewers or coaching staff in near real-time.
Amazing. And here is a short YouTube video that will add to your understanding.
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