The history and technology behind the Virtual Yellow Line
I love good technology, especially when it makes our life better and not more complex. One of the areas technology has made a huge impact is watching American Football.
In my opinion, football is one of those sports that is best watched on TV than in person. With the recent developments in broadcasting football, the game has become even easier and more entertaining to watch.
I've always been fascinated in the yellow line and additional changes made to live football broadcasts. At this point, it is becoming more and more akin to Madden Football game, and this is a good thing!
As you likely already know, the yellow line represents the first down marker. This is drawn in real time and adjusted as the first down target moves. There is an additional line called the line of scrimmage marked in blue, this uses the same technology (which I will go into shortly) as the yellow line and marks the starting point for the ball each down.
Depending on the network, there are additional overlays used throughout the game like the yardage marker you see in the picture above and sometimes even a field goal target line (not shown).
History of the yellow line technology
A company named SportsVision made a product for Basketball that shows how high players jump. They also had an overlay for Hockey that showed a glowing area around the puck so viewers could follow the game better. Neither of these technologies were popular and ended up being canceled fairly quickly.
It was in 1998 when the technology was first used on ESPN without previous announcement. The change was extremely popular and even won SportsVision an Emmy for Technology. It wasn't long before every broadcasting station was using SportsVision technology. At the time, the technology cost the network $25,000 per game.
A few years later Fox tried to reduce it's expenses by removing the yellow line technology from their broadcasts which was met with a lot of frustration. SportsVision started a survey and a website (LoveTheLine.com) and found 92% of people wanted the technology back. Less than 30 days later they received a sponsorship from Intel and the line returned.
There are now three companies providing the technology behind the magic yellow line.
How does the technology work?
The magic behind the yellow line is generating a computer model of the playing field before each game. This is done using sensors and cameras feeding into a network of computers to build a computer representation of the playing field. The pan, tilt, and zoom of cameras are all synchronized with this data.
Once a model of the field is made, color samples are taken from the field to create an accurate color palette for the field. This takes in account lighting, grass coverage, and other factors. These colors are safe colors for the line and other overlays to cover during the broadcast.
Based on which teams are playing, the jersey colors are then added as a suppression palette. Additional colors are added to this palette for cleats, penalty flags, and the football. These colors will never be covered during a broadcast. This works amazingly well except for during really bad weather. During snow games is usually the only time you will see the yellow and blue line covering a player.
All this data is fed to a truck in the parking lot and integrated into the broadcast with a refresh rate of 60 frames per second. This high refresh rate minimizes glitches and jittering.
During snow games the technology is used to overlay line numbers when the real ones are covered. More and more uses for this technology is being thought of as they make the broadcasts more interactive in real time.
In the past the NFL required the yellow line to be turned off when the refs were measuring, the technology has become so accurate this is no longer required.