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3-D software controls 1st down line on TV

Probably every football fan in the world wants to know how television creates the yellow 1st down line.

— Lou, Ashland

We're not sure how intricate of an answer you're seeking, Lou.  To spare readers any unnecessary trips down the tech rabbit hole, the short answer is "computers."

And now for the long answer.

The 1st & Ten computer graphics system by Sportvision and that now-common yellow line made its debut on Sunday, Sept. 27, 1998, when the Cincinnati Bengals-at-Baltimore Ravens game was boradcast on ESPN's Sunday Night Football.

Sportvision is a private company that develops and licenses various technologies enhancing televised sports. If you watch NASCAR, you've probably seen their work with those little flags above race cars identifying the driver, or if you're a baseball fan, you've seen their PITCHf/x system that tracks pitchers' speeds and trajectories during Major League Baseball games on Fox, TBS and MLB.com Game Day.

1st & Ten works with a model of the field's unique shape. No field is perfectly flat in order to facilitate drainage, but each one is different. The system works from a 3-D model of the field before the game. Three cameras, called "instrumented cameras," typically at the 50-yard line and one at each 20-yard line, feed information to the system from lens sensors running at 30 times per second with information such as camera angle, zoom, pan and tilt.

The 3-D model also includes a unique color palette.  Unless we're talking about the Boise State Broncos' stadium (you know, the blue field), the system is usually set to filter shades of green for the line image. 

For particularly snowy conditions, the system is capable of showing all boundaries of the field using information from the system's 3-D model of the field.

When the system was first rolled out in the 1990s, it required seven computers and a crew of four. New versions of the system only require four computers — one for each camera plus a shared computer for color filtering and other tasks — and only one crew member.

Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@mailtribune.com. To see a collection of columns, go to mailtribune.com/youasked. We’re sorry, but the volume of questions received prevents us from answering all of them.