Working of Hawk-Eye Technology.

Cricket is a game where win or loss is defined by a thin margin. Currently, a lot of money is involved in the game and a huge number of spectators are waiting to see a favorable result for their team. Therefore, not only the responsibility of players to win and play without mistakes, but accuracy of decisions made by umpires have became critically important factors.

However, umpires are also human. Naturally, there may be errors when they take decisions. To support umpires to take the correct decision (and minimize the margin of error), lot of new technical utilities have been used recently. This is going to be about one of those technical advancements of the sport; Hawk-eye.

Hawk-Eye is basically a complex computer system used in cricket, tennis and some other sports to visually track the path of the ball used in the game. Upon tracking the path, the system is capable of projecting the continual path (most statistically likely path) of the ball and render it in to video. In cricket, those predictions are used to visualize the path of the ball and aid the umpire to determine what could have happened (i.e. whether the ball could have hit the stumps unless it had been blocked by the pads of  the batsman).

This technology was initially developed by engineers at Roke Manor Research Limited of United Kingdom, in 2001. Later, the research and development of this technology grown into a separate new company, Hawk-Eye Innovations Ltd.

The term “Hawk-Eye” was coined by cricket commentators, but later the phrase was also adopted into Tennis, Snooker and Coaching. From there onward, this technology has become a necessary utility for sport.

How does it work?

Hawk-eye consists of image processing technologies, 3D modeling technologies and laws of physics. There should be at least four high speed cameras placed at different locations of the stadium covering the whole play in different angles. During each frame of the video captured by those cameras, computer system identifies the group of pixels which corresponds to the actual ball. Usually the cameras used in hawk-eye system record the action at 60 frames a second, which is about double the speed of standard commercial TV cameras. The following image shows the positions of the cameras while covering a tennis match.

After that, the three dimensional position of the ball is calculated by comparing the position against at least two other cameras (at least three cameras in total). Then those derived 3D location data are stored in a predefined model of the playing area (stadium). This process is called as ‘triangulation’.

Even though it calculates the three dimensional location, it’s more likely a "four-dimensional" technology, because the time is also added to the triangulation process. So that places the ball in space, are synchronized with the time. Accuracy of the position is pretty impressive as it gives the location with a precision in millimeters.

Using those location data, system can calculate the next movements of the ball by applying laws of physics. System is capable of calculating where the ball will interact with any of the playing area features already programmed into the database.  Furthermore Hawkeye can be taught about the game rules so it can take more sophisticated decisions for human umpires.

Finally to produce the visual guide, system generates a real time graphic image of the ball path and playing area, which can be used for the benefits of umpires, television viewers or coaching staff.