Hawk-Eye in Cricket: How Ball-Tracking Transformed DRS

Hawk-Eye is a computer vision and ball-tracking system developed by Paul Hawkins and used in cricket since 2001. It uses multiple high-speed cameras to track the ball's trajectory and predict where it would have gone had it not hit the batsman's pad. In cricket's Decision Review System (DRS), Hawk-Eye provides the ball-tracking component that umpires and television viewers use to evaluate LBW decisions.

How Hawk-Eye Works

Hawk-Eye uses six or more high-speed cameras positioned around the ground, capturing the ball at over 100 frames per second. The system triangulates the ball's position in 3D space across camera feeds, building a real-time trajectory. When a batsman is struck on the pad, Hawk-Eye calculates the ball's path post-impact — accounting for the spin or swing already in play — and projects whether it would have struck the stumps. The projection is shown as a colour-coded zone on the stumps.

Umpire's Call and the Impact Zone

When a ball is predicted to hit the stumps but only just, the DRS uses an 'umpire's call' concept. If the projected ball is clipping the edge of the stump — within the defined zone — the on-field umpire's decision stands. If the ball is shown to hit or miss the stumps by a larger margin, it overrides the umpire. Hawk-Eye also determines whether the ball pitched inside the return crease and whether impact occurred inside the line of off stump.

Hawk-Eye in Other Sports

Hawk-Eye technology was first commercially deployed in cricket but is now used in tennis (line-calling), snooker (ball-tracking for television graphics), football (goal-line technology), badminton and rugby. Its cricket application remains the most complex because the system must model ball spin, seam movement and pitch variation simultaneously to project an accurate post-impact trajectory.