Abstract
The Hawk-Eye line-calling system in tennis uses a footprint of the ball to determine whether the ball was in or out. However, the footprint itself is not measured. It is the ball trajectory through the air that is measured. Measurements of the footprint are presented in this paper, showing how the high initial rate of expansion of the footprint and other technical difficulties can lead to potential errors in the Hawk-Eye system. The footprint was measured for vertical and oblique impacts, and is compared with recent results presented at a tournament where Hawk-Eye was installed.
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Acknowledgments
The author thanks Joe Fisher for useful discussions concerning the footprint of a tennis ball.
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Cross, R. The footprint of a tennis ball. Sports Eng 17, 239–247 (2014). https://doi.org/10.1007/s12283-014-0159-x
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DOI: https://doi.org/10.1007/s12283-014-0159-x