The Hawk-Eye system uses strategically-placed cameras to determine the exact flight of a ball and is already used in international cricket and at grand slam tennis tournaments.

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While both CAIROS and GoalRef use magnetic fields around the goal and need to insert a chip in the ball, Hawk-Eye and GoalControl use a 3D imaging system to determine the precise location of the ball.

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Left-armer Johnson was varying his length with a degree of unpredictability and shortly before lunch he struck, trapping Gambhir with a delivery that Hawk-Eye showed would have missing leg stump.

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