What techniques are used to judge whether the ball is out of bounds in tennis? What is the principle?

The official name of "Hawkeye" is "instant playback system". The technical principle is not complicated, but it is very accurate. This system consists of eight or 10 high-speed cameras, four computers and a big screen. Firstly, with the help of computer calculation, the three-dimensional space in the competition venue is divided into measurement units calculated in millimeters; Then the basic data of tennis flight trajectory are captured from different angles by high-speed camera at the same time; Then through computer calculation, these data are generated into three-dimensional images; Finally, using real-time imaging technology, the movement route and landing point of tennis can be clearly displayed on the big screen. From data collection to result presentation, the time spent in this process does not exceed 10 second. Usually used for TV broadcasting. As early as the beginning of 200 1, this technology won the scientific and technological innovation award of the Royal Television Association, and in 2003, it won the Emmy Award, the highest award in American television for its wide application in tennis broadcasting. For professional tennis players, it is a significant innovation to introduce eagle-eye technology into tennis spot penalty, which is comparable to the introduction of tiebreak system 36 years ago. The player's request to watch the replay of Hawkeye is a dissatisfaction with the referee's penalty and a challenge to the referee's authoritative position on the court. American star Corell, a four-time Grand Slam winner who specializes in auditing the use of this technology, said: "This is a huge progress for a sport that rarely changes its tradition."