Welcome to brain Stuff from how stuff works dot com where smart Happens. Hi and Marshall brain with today's question, how do they superimpose the first down line onto the field on televised football games? This is one of those things that sounds really simple in theory, but it ends up being incredibly complicated when you actually try to do it. The system that ESPN uses to paint the line is called first and ten and it's created by a company
called sport Vision. The simplest description of the system is this, The first down line is drawn on the field with the computer so that viewers seeing the game on TV can see the line as though it were painted on the field. Here are some of the problems that have to be solved in order for this system to work. First, the system has to know the orientation of the field with respect to the camera so that it can paint the first down line with the correct perspective from the
camera's point of view. Second, the system has to know, in the same perspective framework exactly where every yard line is. Third, given that the camera person can move the camera, the system has to be able to sense the cameras movement tilt, pan, zoom, and focus and understand the perspective change resulting from that movement. Fourth, a football field is not flat. It crests very gently in the middle to help rainwater run off, so the
line calculated by the system has to appropriately follow that curve. Five. The football game is shot by multiple cameras at different places in the stadium, so the system has to do all this work for several different cameras. Six, the system has to be able to sense when players, referees, or the ball cross over the first down line so it doesn't paint the line on top of them. And seventh, the system has to be aware of superimposed graphics that
the network might overlay on the scene. There are probably several other complications as well. It's a tough problem. To solve these problems. The creators of the first intense system combine hardware and software. First, each camera must have very sensitive encoders attached so it can read the cameras angle, tilt, zoom, and so on and send that information to the system.
The system must also have a detailed three D model of the field so that it knows where each yard line is by integrating the tilt, pan, and zoom information with the three D model, the system can calculate where the line should go. Then the system uses color palettes for the field and for the players, referees, and balls to recognize pixel by pixel, whether it's looking at the field or something else. This way, only the field gets painted.
According to the sport Vision website, all of this computation requires a lot of equipment. There are eight computers, three sets of special encoders, and a lot of wiring dedicated to generating the virtual first down line in video format. Who would have thought that it would be this complicated. Do you have any ideas or suggestions for this podcast? If so, please send me an email at podcast at
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