l attended a few pro matches recently and l could not find the equipments that create those woooooooooaaaaa 3-D graphics instant replays.. l figure that there should be hundreds of little cameras surrounding the stadium.

G'day. It is called Hawk-Eye technology. It uses computer sensors, graphically depicts the ball landing near the line and is not a video replay of the shot, so you wo not see small cameras. The chair umpire has access to the technology.

You're right, its done with cameras placed around the court but its not hundreds, usually only 4. Each camera zeroes in on the ball & by triangulation, tracks it, determines its trajectory (which u also see on replays) & of course, whether it lands in or out. It is very expensive which is why u will only see it on one or two show courts. And its not perfectly accurate either. Tests have shown that on average, it is off by .3 mm when it comes to calls. Its called Hawkeye by the way after its inventor, Paul Hawkins.