Slashdot Mirror
Casting Doubt On the Hawkeye Ball-Calling System
Human judgment by referees is increasingly being supplemented (and sometimes overridden) by computerized observation systems. nuke-alwin writes "It is obvious that any model is only as accurate as the data in it, and technologies such as Hawkeye can never remove all doubt about the position of a ball. Wimbledon appears to accept the Hawkeye prediction as absolute, but researchers at Cardiff University will soon publish a paper disputing the accuracy of the system."
Further to that, if the transmitter can't survive in a soccer ball (where a well-struck shot probably moves around 120-130 kph) then there's no way it will handle travelling over 200 kph after a serve, followed by a (at least) 100 kph forehand return (a net >-300 kph in a fraction of a second!).
Also, a radio transmitter cannot account for the distortion of a ball upon impact, which will depend on velocity, angle of rotation, angle of impact, surface being played on, etc etc etc...
Triangulation of radio signals is not accurate enough to give sub-centimeter accuracy and the added mass to the tennis ball would probably cause the players to have some objection to adding a radio transmitter into the ball.
The claim that the Hawkeye system gives an average of about four millimetres of error seems somewhat reasonable, given that we're getting accuracy greater better than two centimetres on detecting objects with a single camera with optics as large as the last segment of a typical pinky. (FWIW, here's a short demo of what we're working on for our autonomous underwater vehicle)
However, the suggestion to display the error range for a particular shot and leaving the final decision to a human from TFA is quite reasonable and is how it should be. Blindingly trusting technology or discarding it altogether is unreasonable.
Jean-Francois Im's blog
I still don't understand why there isn't more research on developing a surface for the out-of-bounds area that temporarily registers the exact impression of any impact on it.
I envision something that looks like a big LCD touch screen (but more durable). Every time something made contact with the active surface, a record of the ball's "footprint" could be recorded (and even temporarily displayed wherever it touched the surface). That would allow for highly precise measurement of the ball's landing position, and it wouldn't need to incorporate any new materials into the ball itself. The active surface would only need to be in the out of bounds area, and even then, it would only need to be half a foot wide in order to cover the important zone where the ball's landing position is questionable.