Buzz
If you're at a Super Bowl party this Sunday, you might hear someone casually ask, 'How do they put that yellow first-down line on the field?' While 'magic' could work as an answer, the true explanation is much more grounded in technology. Let’s dive into the story and the tech behind the shining yellow line that every football fan knows well.
As noted in Allen St. John’s 2009 book The Billion Dollar Game: Behind the Scenes of the Greatest Day in American Sport - Super Bowl Sunday, the yellow first-down line emerged from the ashes of a significant failure in sports broadcasting: the FoxTrax system for hockey, created by a company called Sportvision. FoxTrax—which hockey fans might recall as the infamous 'technopuck' from 1996—used cameras and sensors around the rink to put a small blue halo around the puck.
FoxTrax wasn't well-suited for NHL broadcasts: die-hard hockey fans despised the disruption to the game, and casual viewers didn’t suddenly flock to hockey just because they could track the puck more easily. Still, the technology sparked new ideas for how producers could integrate computerized visuals into live sports broadcasts.
The concept of using a line to indicate the first down in football was a natural progression, and Sportvision launched its 1st and Ten system during an ESPN broadcast of a Bengals-Ravens game on September 27, 1998. A few months later, competing company Princeton Video Image revealed its Yellow Down Line system during a Steelers-Lions game on CBS. (Sportvision is still operational, and in December 2010, ESPN acquired all of PVI’s intellectual property.)
BUT HOW DOES IT FUNCTION?
Creating the yellow first-down line requires a combination of numerous computers, sensors, and skilled technicians. Before the game even starts, technicians create a digital 3D model of the field, including the yard lines. While a football field might seem flat to the eye, it actually has a subtle curve with a crown in the center to help rainwater drain off. Each stadium has its unique terrain, so broadcasters need to have a 3D model of each field before the season kicks off.
These 3D field models help solve many of the technical difficulties in placing a line on the field. On game day, every camera used in the broadcast is equipped with sensors that track its position, tilt, pan, and zoom, sending this data back to the network’s graphics truck parked at the stadium. These readings enable the computers in the truck to determine exactly where each camera is within the 3D model and the angle of each shot. (According to How Stuff Works, the computers adjust the perspective 30 times per second as the camera moves.)
Once the graphics truck has all the data, the team knows precisely where to place the first-down line, but that’s just part of the challenge. When you watch the game, the first-down line appears to be physically painted on the field; even if a player or official crosses it, they don’t turn yellow. It seems as though the player’s cleat is stepping over a real painted line. This illusion is relatively simple to create, but achieving it is far from easy.
To project the line onto the field, technicians and their computers prepare two distinct color palettes before each game. One palette consists of the colors—mainly greens and browns—that are naturally found on the turf. These colors will automatically transform into yellow when the first-down line is generated on the field.
The other palette contains all potential colors that could appear on the field—such as those from uniforms, shoes, footballs, and penalty flags. Colors from this second palette will never turn yellow when the first-down line is drawn. As a result, if a player’s foot is positioned 'on' the line, everything around their cleat will turn yellow, while the cleat itself stays black. According to How Stuff Works, this coloring process refreshes 60 times every second.
All this cutting-edge technology—and the people required to operate it—was quite costly at the start. Initially, broadcasters had to pay between $25,000 and $30,000 per game to add the yellow line to the field. Sportvision needed a truck and a four-person crew with five racks of equipment. Since then, the cost has decreased, and the process is much less labor-intensive. Now, a single technician with one or two computers can run the system, according to Sportvision, and some games can even be done without anyone on-site.
Now you’re ready to impress everyone at your Super Bowl party with this trivia during one of those less-exciting $5 million commercials.
This post originally appeared in 2011.
