Ball-Tracking Technology in Cricket — How Hawk-Eye Works
Ball-tracking technology predicts the ball's path for LBW decisions. Learn how Hawk-Eye works, its accuracy, and how it changed cricket forever.
What Is Hawk-Eye Ball Tracking?
Hawk-Eye is a ball-tracking technology used in cricket's Decision Review System (DRS) to predict the path of a delivery that has been intercepted by the batter's pads (for LBW assessment). Multiple cameras capture the ball's trajectory at high speed (hundreds of frames per second); the system calculates where the ball would have gone had it not been interrupted.
How It Works
- Cameras positioned around the ground capture the ball's path from the moment it leaves the bowler's hand.
- The system tracks the ball in three dimensions using triangulation from multiple camera angles.
- Where the ball hits the pad is identified.
- Using physics models (trajectory, bounce, spin), the system extrapolates where the ball would have gone.
- The result is a predicted ball path shown as a graphical overlay — hitting or missing the stumps.
The 'Umpire's Call' System
When the predicted ball path clips the edge of the stumps, the result is classed as 'Umpire's Call' — the on-field umpire's original decision stands. This accounts for the inherent uncertainty in ball-tracking predictions: when the margin of error could change the outcome, the technology defers to the human decision. Umpire's Call applies when impact is on the edge of the stumps or when bounce is borderline.
Accuracy Debates
Ball-tracking is not universally accepted as infallible. Critics note that the ball is not actually tracked once it hits the pad — the path after impact is extrapolated by model, not measured. The Umpire's Call system addresses this uncertainty in part, but debates about specific high-profile decisions continue. Some nations resisted adopting DRS partly due to concerns about Hawk-Eye accuracy.
Frequently asked questions
Is Hawk-Eye 100% accurate?
No — Hawk-Eye is accurate but not perfect. The system's developers acknowledge a margin of error of approximately 5mm in trajectory prediction. The ICC designed Umpire's Call to account for cases where this margin of error could affect the outcome — ensuring the technology doesn't overturn borderline calls.
When was Hawk-Eye first used in cricket?
Hawk-Eye was first used in cricket for television purposes in the early 2000s, primarily as a broadcast tool. It became part of the Decision Review System (DRS) when DRS was introduced in Test cricket from 2009 onward.