1st & Ten ( graphics system ) 1st & Ten is the name for a computer system that generates and displays one version of the yellow first down line that a TV viewer sees during a live broadcast of a college or professional American football or Canadian football game A competing system that performs the same task using different technology is called L - VIS for Live Video Insertion System . The line , which is not physically present on the field and is seen only by the television audience , spans the width of the football field and indicates the location of the first down marker . The purpose of the line is to make it easier for television viewers to follow play on the field . Some television football broadcasts change the color of the line from yellow to red on 4th down , or show a second computer - generated line ( usually blue in color ) that marks the line of scrimmage . The system makes use of a combination of motion sensors mounted on the broadcast cameras to record what they are viewing , and / or the use of match moving computer graphics technology and an enhanced version of chroma key or " green screen " technology . Conception . The idea of creating an on - field marker to help TV viewers identify 1st down distances was conceived and patented in 1978 by David W . Crain , who presented the concept to Roone Arledge and Roger Goodman of ABC News and Sports and to the CBS Technology Center . At the time , both decided the broadcast industry was not ready to use Crain ' s invention . In 1998 , ESPN Programmer Gary Morgenstern and others , revived the idea . ESPN ' s NFL Coordinating Producer , Fred Gaudelli was tasked with overseeing an implementation for their network . The 1st & Ten line was first broadcast by Sportvision , a private company , during ESPN ' s coverage of a Bengals - Ravens game on September 27 , 1998 . A few weeks later , on Thanksgiving Day , 1998 ( October 12 ) , Princeton Video Image ( PVI ) aired their version of the virtual yellow down line on a CBS broadcast of a Pittsburgh Steelers - Detroit Lions game . Four years later , SportsMEDIA introduced a third version during NBC coverage of a Notre Dame game . The rivalry between PVI and Sportvision began with a collaboration . In July 1995 PVI had successfully used their L - VIS ( Live Video Insertion System ) match moving technology to broadcast virtual advertising behind the home plate on a local broadcast of a Trenton Thunder baseball game in Trenton , NJ . In January 1996 , Roy Rosser , Director of Special Projects at PVI saw SportsVision ' s FoxTrax puck on the broadcast of the 1996 NHL All - Star Game and realized that a combination of L - VIS and FoxTrax would allow virtual insertions in a wider range of situations than either could do on their own , given the then power of affordable computers . He contacted Stan Honey , CTO at Sportsvision , and the two companies undertook a joint demonstration of their combined technologies during the 1996 World Series between the Atlanta Braves and the New York Yankees at the Atlanta Fulton County Stadium . The test was not a success and the two companies parted ways , each developing complementary systems that were eventually used to broadcast Sportsvision ’ s “ First and Ten ” line and PVI ’ s “ Yellow Down Line ” . In October 1999 , SportVision sued PVI alleging that PVI ' s virtual signage , first down line , and other products infringed Fox / Sportvision patents . In August 2001 , PVI counterclaimed against Sportvision in the Federal Court action , alleging that Sportvision ' s virtual strike zone and virtual signage products infringed a PVI patent . In 2002 , the companies settled the law suits out of court through a cross - licensing deal . Before the game . Each football field has a unique crown and contour and is not perfectly flat , so a 3D model is made of the field prior to the game . Due to the low amount of change throughout a football season , this 3D model is usually only generated once a season at most . It also has a unique color palette , typically various shades of green , depending on the type of surface ( i . e . real or artificial grass ) and the weather ( e . g . bright , shady or even snowing ) . In addition , after cameras are set up , the position of the camera relative to the field is established to be used in conjunction with the previously created 3D model of the field . Cameras . There are usually a number of cameras shooting the field , but typically only three main cameras are used for an American football broadcast ( one on the fifty - yard line , and one on each twenty - yard line ) . The cameras with video that will be used with the graphics system have electronic encoders within parts of the camera assembly ( in the lens and the moving platform the camera sits on , sometimes called a " panhead " ) that monitor how the camera is used during the game ( pan , tilt , zoom , focus and extender ) . The encoders transmit that info live 30 or more times per second to the broadcaster ' s production truck , where it is processed by Sportvision computers ( typically one for each camera ) . A camera with this type of extra hardware is usually called an " instrumented " camera . This information helps keep the yellow 1st & ten line in the proper place without being distorted whenever the camera follows the players or the ball . In the larger productions , several other cameras can be " instrumented " to work with the graphics system , but these are usually restricted to following additional types : a camera usually placed in a high position to see all the field , typically called the " all 22 " camera , and a camera shooting from above one end - zone , called an " end - zone camera " , or in the industry often just " camera 4 " . The Skycam ( or moving camera attached to cables above the field ) can also be used to draw a yellow line over its video , but the mechanism has some major differences from the typical " instrumented " camera . Crew . For the initial implementation , there were seven computers in total and a crew of four . Recent implementations require around four computers , one computer per camera plus a shared computer for chroma - keying and other tasks , that can be run by a single operator ( although two is optimal ) . The primary operator usually uses a KVM to switch between camera computers and has an extra monitor , keyboard , and mouse setup for the chroma - keying computer . Of the original four - member crew , two members , one inside the stadium and one in front of a computer , communicated the position of the real first down line to make sure everything was working . The third crew member was a troubleshooter . The last crew member monitored the various colors that make up the color palette onto which the line is drawn . In recent setups only a single operator is required for all cameras . The operator clicks on the ball in the video to set the line of scrimmage and right - clicks where the first down line should be ( or presses a button to automatically position it 10 yards in the direction of play ) . If lighting conditions don ' t change that much , the primary operator can also monitor chroma - key settings , but often a secondary operator is used when conditions get too variable . Data . Each set of camera encoders on a camera transmits position data to an aggregator box that translates the digital information into modulated audio where it is sent down to the corresponding camera computer in the truck . This data is synchronized with the video from that camera . At the camera computer the camera position data is demodulated back to digital data for use by the program that draws the " yellow line " over the video . Separately , the chroma - keying computer is told what colors of the field are okay to draw over ( basically grass ) and that information is sent to the camera computers . The old way . The first computer in the truck gathers all the separate readings from the cameras and transmits a single , consolidated data stream to the central computer . The central computer takes these readings , the 3D field model and color palette , the knowledge of which camera is on the air , and together using a geometrical calculation determines which pixels in the video frame would make up the first down line . All pixels that are obstructed by a player , a referee , the ball or any other object are identified and not included in the calculation . This will ensure that the 1st & Ten line will be projected only onto the field . The PVI Virtual Media system relies on a signal on a single spotter to relay the down and distance , and a single operator at the studio as their vision system does not need camera data to perform the insertion . The primary operator of the Sportvision system does the spotting by merely clicking on the video to place the line . Technology errors . The only pixels that should change are the ones that are the same color as the field , typically several shades of green . As a result , there are a few situations that are difficult . One is when the player ' s uniform color nearly matches that of the field ( for example , the Green Bay Packers ' jersey on a bright , sunny day , or for Boise , Idaho ' s Bronco Stadium , where the field and the home team uniform share the same blue shade ) . The other is when the field itself changes , like during a rain / snow storm or if the grass field becomes very muddy . In those cases , the field ' s color palette would need to include brown and / or white shades . The most difficult situations are when the shade of the field is constantly changing as in situations where moving clouds are shadowing the field on some spots , but not others , but continue to move across the field . The data collection and computation also requires time . The audio feed goes to an audio delay to be synchronized with the delayed video . The total delay for the viewer from the live feed ends up being about 2 / 3 of a second . Final result . After the camera computer has determined which pixels represent the 1st & Ten line , it takes that pixel information and draws the yellow line in video format at around 60 times per second ( depends on video refresh frequency ) . In recent years the system has been upgraded to add more features . During Fox broadcasts , the Sportvision system also generates an arrow - like graphic on the field with down and distance text information inside of an arrow pointing in the direction of play . Competitors have also added this feature in recent years . Additionally , the Sportvision system can also place virtual graphics that have another embedded video feed inside them like a video picture frame . This is sometimes called " video - in - perspective " . This technology is also the basis for showing ads where they may not appear ( i . e . behind home plate in baseball during national broadcasts ) , and Race F / X in which images can be displayed on the race track , and info can follow a specific car , no matter what the camera does . This technology is used by CBS , ESPN , Fox , NBC , NFL Network , RDS , TSN , and TNT .