How Does the Magic Yellow First-Down Line Work?

Sportvision
Sportvision

If you attend a Super Bowl party on Sunday, you’ll probably hear at least one casual football viewer ask, “How do they get that yellow first-down line on the field?” While “magic” is a fine answer in its own right, the real explanation is a bit more technologically intense. Let’s have a look at the background and mechanics behind every football fan’s shining beacon: the yellow first-down line.

According to Allen St. John’s 2009 book The Billion Dollar Game: Behind the Scenes of the Greatest Day in American Sport - Super Bowl Sunday, the first-down line actually emerged from the ashes of one of sports broadcasting’s bigger debacles: the FoxTrax system for hockey, which was designed by a company called Sportvision. FoxTrax—which hockey fans no doubt remember as the much-maligned “technopuck” that debuted in 1996—employed a system of cameras and sensors around a hockey rink to place a little blue halo around the puck.

FoxTrax wasn't a great fit for NHL broadcasts: Hockey purists hated the intrusion into their game, and casual fans didn’t flock to hockey just because the puck was suddenly easier to follow. However, the system inspired producers to think of new ways to insert computerized images into live sports broadcasts.

The idea of using a line to mark the first down in football was a natural extension, and Sportvision debuted its 1st and Ten system during ESPN’s broadcast of a Bengals-Ravens tilt on September 27, 1998. A couple of months later, rival company Princeton Video Image unveiled its Yellow Down Line system during a Steelers-Lions broadcast on CBS. (Sportvision is still kicking, and ESPN acquired all of PVI’s intellectual property in December 2010.)

BUT HOW DOES IT WORK?

It takes lots of computers, sensors, and smart technicians to make this little yellow line happen. Long before the game begins, technicians make a digital 3D model of the field, including all of the yard lines. While a football field may look flat to the naked eye, it’s actually subtly curved with a crown in the middle to help rainwater flow away. Each field has its own unique contours, so before the season begins, broadcasters need to get a 3D model of each stadium’s field.

These models of the field help sidestep the rest of the technological challenges inherent to putting a line on the field. On game day, each camera used in the broadcast contains sensors that record its location, tilt, pan, and zoom and transmit this data to the network’s graphics truck in the stadium’s parking lot. These readings allow the computers in the truck to process exactly where each camera is within the 3D model and the perspective of each camera. (According to How Stuff Works, the computers recalculate the perspective 30 times per second as the camera moves.)

After they get their hands on all of this information, the folks in the graphics truck know where to put the first-down line, but that’s only part of the task. When you watch a football game on television, you’ll notice that the first-down line appears to actually be painted on the field; if a player or official crosses the line, he doesn’t turn yellow. Instead, it looks like the player’s cleat is positioned on top of an actual painted line. This effect is fairly straightforward, but it’s difficult to achieve.

To integrate the line onto the field of play, the technicians and their computers put together two separate color palettes before each game. One palette contains the colors—usually greens and browns—that naturally occur on the field’s turf. These colors will automatically be converted into yellow when the line is drawn on to the field.

All of the other colors that could show up on the field—things like uniforms, shoes, footballs, and penalty flags—go into a separate palette. Colors that appear on this second palette are never converted into yellow when the first-down line is drawn. Thus, if a player’s foot is situated “on” the line, everything around his cleat will turn yellow, but the cleat itself will remain black. According to How Stuff Works, this drawing/colorizing process refreshes 60 times per second.

All this technology—and the people needed to run it—wasn’t cheap at first. It could cost broadcasters anywhere from $25,000 to $30,000 per game to put the yellow line on the field. Sportvision had to deploy a truck and a four-man crew with five racks of equipment. The cost has come down since then, and the process is now less labor-intensive. One technician using one or two computers can run the system, according to Sportvision, and some games can even be done without anyone actually at the venue.

Now you can explain it to everyone at your Super Bowl party during one of the less-exciting $5 million commercials.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This post originally appeared in 2011.

Does the Full Moon Really Make People Act Crazy?

iStock.com/voraorn
iStock.com/voraorn

Along with Mercury in retrograde, the full moon is a pretty popular scapegoat for bad luck and bizarre behavior. Encounter someone acting strangely? Blame it on the lunar phases! It's said that crime rates increase and emergency rooms are much busier during the full moon (though a 2004 study debunked this claim). Plus, there's that whole werewolf thing. Why would this be? The reasoning is that the Moon, which affects the ocean's tides, probably exerts a similar effect on us, because the human body is made mostly of water.

This belief that the Moon influences behavior is so widely held—reportedly, even 80 percent of nurses and 64 percent of doctors think it's true, according to a 1987 paper published in the Journal of Emergency Medicine [PDF]—that in 2012 a team of researchers at Université Laval's School of Psychology in Canada decided to find out if mental illness and the phases of the Moon are linked [PDF].

To test the theory, the researchers evaluated 771 patients who visited emergency rooms at two hospitals in Montreal between March 2005 and April 2008. The patients chosen complained of chest pains, which doctors could not determine a medical cause for the pains. Many of the patients suffered from panic attacks, anxiety and mood disorders, or suicidal thoughts.

When the researchers compared the time of the visits to the phases of the Moon, they found that there was no link between the incidence of psychological problems and the four lunar phases, with one exception—in the last lunar quarter, anxiety disorders were 32 percent less frequent. "This may be coincidental or due to factors we did not take into account," Dr. Geneviève Belleville, who directed the team of researchers, said. "But one thing is certain: we observed no full-moon or new-moon effect on psychological problems."

So rest easy (or maybe not): If people seem to act crazy during the full Moon, their behavior is likely pretty similar during the rest of the lunar cycle as well.

This story was updated in 2019.

What's the Difference Between a Rabbit and a Hare?

iStock.com/Carmen Romero
iStock.com/Carmen Romero

Hippity, hoppity, Easter's on its way—and so is the eponymous Easter bunny. But aside from being a magical, candy-carrying creature, what exactly is Peter Cottontail: bunny, rabbit, or hare? Or are they all just synonyms for the same adorable animal?

In case you've been getting your fluffy, long-eared mammals mixed up, we've traveled down the rabbit hole to set the record straight. Although rabbits and hares belong to the same grass-munching family—called Leporidae—they're entirely different species with unique characteristics. It would be like comparing sheep and goats, geneticist Steven Lukefahr of Texas A&M University told National Geographic.

If you aren't sure which animal has been hopping around and helping themselves to the goodies in your vegetable garden, take a closer look at their ears. In general, hares have longer ears and larger bodies than rabbits. Rabbits also tend to be more social creatures, while hares prefer to keep to themselves.

As for the baby animals, they go by different names as well. Baby hares are called leverets, while newborn rabbits are called kittens or kits. So where exactly do bunnies fit into this narrative? Originally, the word bunny was used as a term of endearment for a young girl, but its meaning has evolved over time. Bunny is now a cutesy, childlike way to refer to both rabbits and hares—although it's more commonly associated with rabbits these days. With that said, the Easter bunny is usually depicted as a rabbit, but the tradition is thought to have originated with German immigrants who brought their legend of an egg-laying hare called "Osterhase" to America.

In other ambiguous animal news, the case of Bugs Bunny is a little more complicated. According to scientist and YouTuber Nick Uhas, the character's long ears, fast speed, and solitary nature seem to suggest he's a hare. However, in the cartoon, Bugs is shown burrowing underground, which doesn't jive with the fact that hares—unlike most rabbits—live aboveground. "We can draw the conclusion that Bugs may be a rabbit with hare-like behavior or a hare with rabbit nesting habits," Uhas says.

The conversation gets even more confusing when you throw jackrabbits into the mix, which aren't actually rabbits at all. Jackrabbits are various species of large hare that are native to western North America; the name itself is a shortened version of "jackass rabbit," which refers to the fact that the animal's ears look a little like a donkey's.

A jackrabbit
Connor Mah, Flickr // CC BY-SA 2.0

As Mark Twain once famously wrote about the creature, "He is just like any other rabbit, except that he is from one-third to twice as large, has longer legs in proportion to his size, and has the most preposterous ears that ever were mounted on any creature but the jackass." (Fun fact: Black-tailed jackrabbits' extra-long ears actually help them stay cool in the desert. The blood vessels in their ears enlarge when it gets hot, causing blood to flow to their ears and ridding their bodies of excess heat.)

Rabbits, hares, and jackrabbits all have one thing in common, though: They love a good salad. So if you happen across one of these hopping creatures, give them some grass or weeds—and skip the carrots. Bugs Bunny may have loved the orange vegetable, but most hares and rabbits would prefer leafy greens.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

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