Ball Tracking Systems in Cricket
The original ball tracking system that was used in cricket was hawk-eye, which is able to trace a cricket ball's trajectory, with a claimed accuracy of 5 mm, which can be used to adjudicate LBW decisions. More recently, a rival system Virtual Eye (also called Eagle-Eye) provides a similar service. Virtual Eye was first used for tracking sailing events.
Method
The ball tracking system makes use of six or more computer-linked cameras situated around the cricket field of play. The computer reads in the video in real time, and tracks the path of the cricket ball on each camera. These multiple views are then combined to produce an accurate 3D representation of the path of the ball.
History
The Hawk-eye system was launched in 2001. It was first used in television coverage of sporting events such as Test cricket, and has now reached the stage of being used by officials in tennis to assist in adjudicating close line calls. In 2010, Virtual Eye (at the time called Eagle-Eye) was first used for the Ashes series.
Uses
A ball tracking system was first used during a Test match between Pakistan and England at Lord's Cricket Ground, on 21 April 2001, in the TV coverage by Channel 4. Since then it has been an indispensable tool for cricket commentators around the world. It is used primarily by the majority of television networks to track the trajectory of balls in flight, primarily to assist the umpire in leg before wicket decisions.
In the case of LBW decisions, Hawk-Eye is able to project the likely path of the ball forward, through the batsman's legs, to see if it would have hit the wicket. In addition to providing information to TV viewers, the technology is also used by the third umpire to adjudicate LBW decisions that have been referred.
ball tracking The ball-by-ball tracking by the Hawk-Eye system also allows the broadcasters to showcase many other features of the game, such as comparing the bowlers' speeds, spin, swing, line and length.
In additional to ball tracking for LBW decisions, Virtual Eye also provides the broadcasters Wagon Wheels, Pitch Maps, Beehives, Deviation of Seam/Spin, Fireworks, Field Placement, Six Distances plus much more.
Criticisms
Although Hawkeye is very accurate in measuring the actual path of a ball, when it comes to predicting the future path of the ball, such as in LBW decisions, it is not as clear. If the ball is heading to the pitch, there's no way Hawk-eye can tell if a delivery is going to skid a bit more than normal or hit a crack, bit of grass, or worn patch of the pitch. The predicted path of the ball is based on the average and expected pathway. Virtual Eye claims to have a better accuracy, using a higher frame rate camera to help track the ball movements.
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