The Tech Behind the Football’s Broadcast-Only First Down Line

• sports
• Super Bowl
• NFL
• football
• technology

Photo by Getty Images/Al Bello

“Didn’t he see the line?” That’s a question you might hear from a football neophyte at a Super Bowl party as you watch a running back fall to the ground just short of a first down on Sunday.

The yellow first-down line has become such a seamless part of football broadcasts like NBC’s that it’s sometimes hard to remember that it’s only there for the benefit of the fans at home. But there’s a tremendous amount of technology behind this seemingly simple innovation, and its origins can be traced back to, of all things, a failed experiment in NHL hockey.

In the mid-1990s, FOX Sports CEO David Hill and president Ed Goren came up with the idea of superimposing a line on the screen to show viewers just how far the offense needed to go for a first down. While this idea wasn’t as controversial as some of their earlier changes—the Fox Box score graphic prompted death threats—the execs quickly found out that implanting the first-down line wouldn’t be nearly as easy as it first seemed.

It turns out that there was a mountain of technical problems. The view from each camera was in constant flux, changing the perspective as it zoomed, panned and tilted. Adding to the complexity is the fact that the ball moved up and down the field in minute increments. Finally, the field itself isn’t completely flat, but gently crowned. It becomes easy to see how a simple telestrator-like line simply wouldn’t do.

“It sounded simple, but we tried to do it with the equipment we had, and we couldn’t do it,” Goren recalls. “We had to get the technology.”

The technology came from NHL hockey. FOX had just secured the rights to professional hockey, and in an attempt to make the game more accessible, Hill and Goren devised FOX Trax in conjunction with a small company called Silicon Graphics. The system consisted of array of infrared sensors and a battery buried inside an otherwise regulation hockey puck. The movement of the puck could then be captured by a series of infrared cameras around the arena. The data was fed to a network of computer processors so extensive that they took up a whole separate broadcast trailer. The result? The puck would glow blue, which made it somewhat easier to see, and would grow a comet-like tail when a shot exceeded 40 mph. The glowing puck outraged some hockey purists. While casual viewers did seem to appreciate the help, the technology had little impact on hockey ratings.

But this shotgun marriage between a live video feed and real-time computer graphics made the first-down line possible by 1996. The current system feeds data about the pan, tilt, zoom and focus of each camera over an audio channel to the graphics truck, where it’s decoded and overlaid on the video feed. The information is refreshed 60 times a second to keep up with the action. A series of color filters, with a technician watching to finesse the details, keeps the lines on the field, but not superimposed on the players, the ball or the referees. If a team had uniforms the exact color of AstroTurf, it would cause problems. While all this technology isn’t cheap—on FOX broadcast it exceeds $25,000 a game—the result is a line so realistic that it looks as though it were painted by a groundskeeper.

Adapted from The Billion Dollar Game: Behind the Scenes of the Greatest Day in American Sport—Super Bowl Sunday, By Allen St. John, published this month by Doubleday.

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