Hawk Eye (Sky Scope)

In 2001, Sky boast that they were there first, but Hawk-Eye is now established as the market leader. Derived from missile-tracking technology, it relies on a number of fixed and calibrated camera positions to produce a 3D grid which then is used to track the ball and predict where it would have gone. In its early days many doubted its accuracy but by and large there are few moans now. Some even argue it has led to umpires being more likely to give lbw decisions when the batsman is on the front foot, so often did Hawk-Eye show the ball going on to hit the stumps. It still suffers occasional glitches, such as in 2005 when Shane Warne ripped a legbreak so far across Michael Vaughan that the computer decided it could not have happened and failed to register the delivery. Nevertheless, it's now widely and effectively used in tennis and, more recently, snooker.