Why does Hawk-Eye count a ball's entire diameter?

Question

From my understanding, the line rule in tennis requires that a ball physically (i.e., the actual ball surface) touch a line for it to count as having "hit the line." So why does Hawk-Eye count the ball's entire diameter? Even if one believes Hawk-Eye to be generally more accurate than human eyes, doesn't that approach lead to too many balls being called "in"?

Answer 1

Hawk-Eye is a multi-camera system which electronically tracks the flight of a moving ball and has become part of the umpiring process on Centre Court and No.1 Court at Wimbledon. The 2007 tournament was the first time this technology was used at Wimbledon by players to challenge an umpire's decision. from http://aeltc.wimbledon.org/en_GB/about/g...

for more info click http://jtsang.blogspot.com/2006/07/techn...

also check http://www.smh.com.au/articles/2005/01/2...

"It is a vision processing system that uses the images from five or six cameras placed around and high above the court to triangulate the ball's flight and build up a 3D (picture) of its position through the rally," he said.

The cameras record the action at 60 frames a second, about double the speed of standard commercial TV.

It is "four-dimensional" technology, adding time to the triangulation that places the ball in space, much as a satellite-based global positioning system locates a car on the road, but with a precision in millimetres rather than metres. In Hawkeye a computer captured the image from each camera and worked out where the ball was in 3D space.

It then combined all that information and traced the trajectory of the ball in each rally, Dr Hawkins said.

"Once you have got the trajectory . . . you can interrogate it for the position of the ball at any specific time" - on, inside or outside the line, he said.

Data calculated at the rate of 1billion equations per rally is turned into a graphic by virtual reality software similar to that used in computer games and it is these images that viewers see on their TV screens.

Answer 2

Hawk-Eye is a computer system used in tennis and other sports to track the path of the ball. It was developed in 2001 by Dr. Paul Hawkins while working at Roke Manor Research Limited. Later, the technology was spun off into a separate company, Hawk-Eye Innovations Ltd., as a joint venture with television production company Sunset + Vine

Hawk-Eye uses six or more television cameras situated around the ground, linked to a computer system. The computer reads in the video in real time, and tracks the path of the ball on each camera. These six separate views are then combined together to produce an accurate 3D representation of the path of the ball, which can be viewed in a virtual reality simulation.

Hawk Eye has the capability of calling ins and outs live, but it was decided to limit it to replays only.

Answer 3

I guess most didn't understand your actual question. When you see it on tv, it shows the full diameter of the ball on the screen vs just the spot that marks the area where the ball actually touched the court. So although the ball touched outside the line, it could actually look like it touched the line from the top.

I believe the display you see is not how it actually looks if you see from the top. The actual spot the ball touches the ground is re-created to look like the inner edge of the ball (closest to the line) and the rest of the ball is simple extra-polated by the computer. In other words, what you see on TV is not what it looks like in reality. You just have to focus on the part of the ball that is closest to the line (if it is called out by hawk-eye). The technology is very interesting and obviously very complex to implement, hardware and software wise.    

Answer 4

no hawk eye actually counts the part of the ball that touches the ground !!

Answer 5

The reason it is called "hawk eye" is because it will grab any percentage of the ball, even if the ball is real fuzzy that hits the line.  It covers any one part of the circumference of the ball meaninging any tiny to large area of the ball.  Any part of the ball that hits the line whether it be a millimeter or even less.  Thus "hawk eye" was born.

Oh almost forgot, any part of the line also front, back middle, side in or out, and line transitions,

I bet John McEnroe would have a scientific answer...lol

I hope I answered your question!