Technology in umpiring December 18, 2003

Give Hawk-Eye a chance

The Sachin Tendulkar lbw: Hawk-Eye showed the ball to be going well over the stumps
© Getty Images

A spate of controversial umpiring decisions has opened up the debate over the use of technology to assist the officials. Many - including, most recently, Dennis Lillee - have rubbished the accuracy of Hawk-Eye, a system which tracks the path of the ball and then predicts its trajectory had it not been intercepted by the batsman. After reading Lillee's comments, Paul Hawkins, managing director of Hawk-Eye Innovations Ltd, wrote to Wisden Cricinfo. Here is an attempt to respond to the charges made by Lillee, and answer a few other queries about the technology.

Predicting bounce
Lillee had questioned any gadget's ability to accurately predict the bounce off the pitch. "From a fast bowler's perspective, there is no way Hawk-Eye can tell if a delivery is going to skid a bit more than normal or hit a crack, or a damp or worn patch, or a bit of grass on the wicket," said Lillee. "Batsmen struggle with the unpredictability of bounce, so how on earth is Hawk-Eye going to know what every ball is going to do, how it comes out of the hand or is angled?"

Hawkins's response: "Hawk-Eye does not try to predict the path of the ball after the bounce. Instead, the Hawk-Eye cameras track the ball both before and after the bounce, so the correct trajectory of the ball leaving the wicket is determined. Hawk-Eye simply observes and then calculates the actual trajectory of the ball. Whether the cause of this trajectory was due to atmospheric conditions, the wicket, or the ball hitting the seam is irrelevant from a Hawk-Eye perspective. Hawk-Eye just tracks what happened - it does not try to predict nor to answer why it happened."

So, if the ball rears up unexpectedly after hitting the seam or a crack on the pitch, Hawk-Eye will track the trajectory off the pitch to predict the future course of the ball. Similarly, the tracking system will come into play if the balls shoots along the ground after hitting a dry spot on the pitch. In fact, Hawk-Eye has shown that balls pitched on roughly the same area on the wicket have passed the stumps at widely varying heights. And in tests conducted, thousands of deliveries were bowled from a bowling machine and filmed by Hawk-Eye. The camera feeds were cut about two metres from the stumps, approximately the point where the batsman would normally intercept the ball. When the ball hit the wicket, Hawk-Eye was able to determine, to within about 5 mm, the point of impact.

What if the ball hits the pads on the full?
Hawkins's reply: "If the ball hits the batsman on the full, then Hawk-Eye performs the same function which the laws ask of the umpire - to assume that the ball would have continued on its current path.

"Hawk-Eye requires between 1 to 2 feet of travel after the ball has pitched to be able to accurately track the ball out of the bounce (this is significantly less than an umpire requires). In instances when this does not happen, a Hawk-Eye replay is not offered to TV (and if used by the umpire the benefit of doubt would go to the batsman)."

Isn't the umpire in the best position to judge lbws?
The umpire does stand right in line with the stumps, but the fact that he stands upright means his eyes are not at stump level, which could lead to incorrect judgement regarding the height of the ball. Experiments were carried out with three umpires - one in the normal standing position, one squatting down in front of him, and one at square leg. Results proved that the umpire squatting, who was level with the wickets, could judge the height of the ball most accurately. The umpire standing behind the stumps often ruled the ball to be hitting, when it was actually going over the top - exactly what happened in Sachin Tendulkar's case at the Gabba.

To accusations that use of such technology would reduce the on-field umpires to glorified counting machines, Hawkins responds: "By no means is it the intention of Hawk-Eye to undermine the role of the umpire. In a very high percentage of cases the Hawk-Eye replay confirms the umpires' decision to have been correct. Hawk-Eye has helped to highlight just how difficult their job is - it is the only decision in any sport which requires a predictive element and from the umpires' angle predicting height is very difficult."

S Rajesh is assistant editor of Wisden Cricinfo.