NFL Graphics

How do they do that graphic first down marker during an NFL game? The players seem do be able to walk on top of it on TV, you know? As if the line isn’t just superimposed on top of the picture. I was imagining it might be something similar to blue screen technology; maybe they are painting the graphic on a certain range of a shade of green. If so, say if a player with a unifrom just the right shade of green stood on top of it - would he appear invisible? I gots ta know.

Laser, I think, though I can’t prove it.

And yes, so far as I know, anything in the way of the line gets it. So the ball does, for example, and the center’s hand(s).

Someone is going to come along a correct me on this but my basic understanding of this comes from a story I saw on it years ago. In the story they interviewed the guys who came up with this technology. Here’s what I remember, a very basic explanation:

There is a set amount of transmitters strategically positioned around the arena, or wherever you want this trick done (I’ve seen it done on a golf course, where they superimposed an add on the fairway, tacky as Hell). The camera they use has a reciever attached to it that recieves these signals. The info from the transmitters and variables like zoom degree are then sent to one monster of a processor. One of the functions of the processor is to triagulate the transmissions so as to find out where and what the camera is ‘looking’ at. Putting the graphic on the image is pretty easy and straightforward. Other techniques are used to hide the line when someone or something interferes with this graphic. If I recall correctly, that was the biggest hurdle the programmers faced.

On some NFL games, you’ll also notice an ad next to the goalposts. The camera moves all over the place, but the ad stays relative to its ‘set’ position. This is the same technology.

Sorry it’s so basic, but others have asked me this same question and have been satisfied with the answer. There’s any number of things I’m sure I left out, but, basically that’s it.

This has been covered in at least two other threads, but I’m too lazy to play with the search engine (sorry). So if I get this wrong, you have my permission to slap me.

CnoteChris is basically right, except I don’t think the transmitters are necessary. If you’ve surveyed the field and have an accurate 3d model, you can just tell the computer to draw a stripe down the 30 yard line and it’ll know where to put it.

To me, the most impressive bit is how well they can calibrate the camera and measure the zoom and direction of it well enough to know where to draw the stripe.

Why do I get the feeling we’ll be seeing this question at least a dozen times before January? Anyway, the hardware and software that go into making this line show up are both very complex.

In addition to a brief description of the process, there are some good links at that site.

I know a guy who works for marketing at SGI - he is quite ready to point to the screen and point out that it is done with SGI computers. Of course, SGI is in the dumper, and this is how they got there - concentrating on state-of-the-art applications rather than selling to the volume end of the market.

Raise your hand if you are happy that they no longer have that glowing puck thing on televised hockey games. Thank you!