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

College football

College football refers to American football played by teams of student athletes fielded by American universities, colleges, and military academies, or Canadian football played by teams of student athletes fielded by Canadian universities...

 or professional American football

American football

American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...

 or Canadian football

Canadian football

Canadian football is a form of gridiron football played exclusively in Canada in which two teams of 12 players each compete for territorial control of a field of play long and wide attempting to advance a pointed prolate spheroid ball into the opposing team's scoring area...

 game A competing system that performs the same task using different technology is called L-VIS

PVI Virtual Media Services

PVI Virtual Media Services is one of the companies behind the virtual yellow-down-line shown on television broadcasts of American football games in the USA and Canada...

 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

Line of scrimmage

In American and Canadian football a line of scrimmage is an imaginary transverse line beyond which a team cannot cross until the next play has begun...

.

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

Chroma key

Chroma key compositing is a technique for compositing two images together. A color range in the top layer is made transparent, revealing another image behind. The chroma keying technique is commonly used in video production and post-production...

 or "green screen" technology.

Conception

The idea of creating an on-field marker to help TV viewers identify 1st down distances was conceived and demonstrated in 1976 by David W. Crain, but the broadcast industry was not ready to use his invention. In 1998, ESPN

ESPN

Entertainment and Sports Programming Network, commonly known as ESPN, is an American global cable television network focusing on sports-related programming including live and pre-taped event telecasts, sports talk shows, and other original programming....

 Programmer Gary Morgenstern

Gary Morgenstern

Gary Morgenstern is an American broadcast executive. He revived the idea of the first and ten mark, first conceived by David Crain, that appears on television to help viewers recognize the distance needed to achieve a first down. At the time he revived the virtual 1st and 10 line idea, he was...

 and others, revived the idea. ESPN's NFL

National Football League

The National Football League is the highest level of professional American football in the United States, and is considered the top professional American football league in the world. It was formed by eleven teams in 1920 as the American Professional Football Association, with the league changing...

 Coordinating Producer, Fred Gaudelli was tasked with overseeing an implementation for their network. The 1st & Ten line was first broadcast by Sportvision

Sportvision

Sportvision is a private company that provides various television viewing enhancements to a number of different professional sporting events. They work with NFL, NBA, NASCAR, NHL, MLB, PGA and college football broadcasts....

, 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 Virtual Media Services

PVI Virtual Media Services is one of the companies behind the virtual yellow-down-line shown on television broadcasts of American football games in the USA and Canada...

 (PVI) aired their version of the virtual yellow down line on a CBS broadcast of a Pittsburgh Steelers

Pittsburgh Steelers

The Pittsburgh Steelers are a professional football team based in Pittsburgh, Pennsylvania. The team currently belongs to the North Division of the American Football Conference in the National Football League . Founded in , the Steelers are the oldest franchise in the AFC...

 - Detroit Lions

Detroit Lions

The Detroit Lions are a professional American football team based in Detroit, Michigan. They are members of the North Division of the National Football Conference in the National Football League , and play their home games at Ford Field in Downtown Detroit.Originally based in Portsmouth, Ohio and...

 game. Four years later, SportsMEDIA introduced a third version during NBC coverage of a Notre Dame game.

The rivalry between PVI

PVI Virtual Media Services

PVI Virtual Media Services is one of the companies behind the virtual yellow-down-line shown on television broadcasts of American football games in the USA and Canada...

 and Sportvision began with a collaboration. In July 1995 PVI had successfully used their L-VIS

PVI Virtual Media Services

PVI Virtual Media Services is one of the companies behind the virtual yellow-down-line shown on television broadcasts of American football games in the USA and Canada...

 (Live Video Insertion System) match moving

Match moving

In cinematography, match moving is a visual-effects, cinematic techniques that allows the insertion of computer graphics into live-action footage with correct position, scale, orientation, and motion relative to the photographed objects in the shot...

 technology to broadcast virtual advertising behind the home plate on a local broadcast of a Trenton Thunder

Trenton Thunder

The Trenton Thunder are an American Minor League Baseball team and are the Double-A affiliate of the New York Yankees. The Thunder play in the Eastern Division of the Eastern League, and are the two-time defending league champions...

 baseball game in Trenton

Trenton, New Jersey

Trenton is the capital of the U.S. state of New Jersey and the county seat of Mercer County. As of the 2010 United States Census, Trenton had a population of 84,913...

 , NJ

Nj

Nj or NJ may stand for:*New Jersey*Nanojoule , an International System of Units unit of energy equal to 10−9 joules*Nj *Narva-Jõesuu, Estonia*Nordjyske Jernbaner, a Danish railway...

. In January 1996, Roy Rosser, Director of Special Projects at PVI saw SportsVision's FoxTrax

FoxTrax

FoxTrax was a specialized ice hockey puck with internal electronics that allowed its position to be tracked designed for NHL telecasts on the Fox television network...

 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

1996 World Series

-Game 1:Sunday, October 20, 1996 at Yankee Stadium in Bronx, New YorkGame 1 and Game 2 were originally scheduled for Saturday, October 19 and Sunday, October 20, respectively. Rain on October 19, however, washed out Game 1. The schedule was moved up one day, with Game 1 and Game 2 rescheduled for...

 between the Atlanta Braves

Atlanta Braves

The Atlanta Braves are a professional baseball club based in Atlanta, Georgia. The Braves are a member of the Eastern Division of Major League Baseball's National League. The Braves have played in Turner Field since 1997....

 and the New York Yankees

New York Yankees

The New York Yankees are a professional baseball team based in the The Bronx, New York. They compete in Major League Baseball in the American League's East Division...

 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

Artificial turf

Artificial turf is a surface manufactured from synthetic fibers made to look like natural grass. It is most often used in arenas for sports that were originally or are normally played on grass. However, it is now being used on residential lawns and commercial applications as well...

 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

Panning (camera)

In photography, panning refers to the horizontal movement or rotation of a still or video camera, or the scanning of a subject horizontally on video or a display device...

, tilt

Tilt (camera)

Tilting is a cinematographic technique in which the camera is stationary and rotates in a vertical plane . A rotation in a horizontal plane is known as panning...

, zoom

Digital zoom

Digital zoom is a method of decreasing the apparent angle of view of a digital photographic or video image. Digital zoom is accomplished by cropping an image down to a centered area with the same aspect ratio as the original, and usually also interpolating the result back up to the pixel...

, focus

Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...

 and extender

Extender

Extender may refer to:*Ascender or descender, in typography and graphonomics*DOS extender, a technology for bypassing the limitations of the DOS operating systems family*KC-10 Extender, an air-to-air tanker aircraft*Meat extenders*Media 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

Skycam

Skycam is the trademarked brandname of a patented, computer-controlled, stabilized, cable-suspended camera system. The system, similar to Steadicam, but maneuvered through three dimensions in the open space over a playing area of a stadium or arena by computer-controlled cable-drive system, is...

 (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 and will not be addressed in this article.

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

KVM switch

A KVM switch is a hardware device that allows a user to control multiple computers from a single keyboard, video monitor and mouse. Although multiple computers are connected to the KVM, typically a smaller number of computers can be controlled at any given time...

 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 & 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'

Green Bay Packers

The Green Bay Packers are an American football team based in Green Bay, Wisconsin. They are members of the North Division of the National Football Conference in the National Football League . The Packers are the current NFL champions...

 jersey on a bright, sunny day). 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

NFL on FOX

NFL on Fox is the brand name of the Fox Broadcasting Company's coverage of the National Football League's National Football Conference games, produced by Fox Sports...

 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

CBS

CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...

, ESPN

ESPN

Entertainment and Sports Programming Network, commonly known as ESPN, is an American global cable television network focusing on sports-related programming including live and pre-taped event telecasts, sports talk shows, and other original programming....

, Fox

Fox Broadcasting Company

Fox Broadcasting Company, commonly referred to as Fox Network or simply Fox , is an American commercial broadcasting television network owned by Fox Entertainment Group, part of Rupert Murdoch's News Corporation. Launched on October 9, 1986, Fox was the highest-rated broadcast network in the...

, NBC

NBC

The National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...

, NFL Network

NFL Network

NFL Network is an American television specialty channel owned and operated by the National Football League . It was launched November 4, 2003, only eight months after the league's 32 team owners voted unanimously to approve its formation...

, RDS

Réseau des sports

Réseau des sports , is a Canadian French language Category C specialty channel showing sports and sport-related shows. It is available in 2.5 million homes, and is owned by CTV Specialty Television Inc....

, TSN

The Sports Network

The Sports Network, commonly abbreviated as TSN, is a Canadian English language Category C specialty channel and is Canada's leading English language sports TV channel. TSN premiered in 1984, in the first group of Canadian specialty cable channels...

, and TNT

Turner Network Television

Turner Network Television is an American cable television channel created by media mogul Ted Turner and currently owned by the Turner Broadcasting System division of Time Warner...

.

External links

• http://www.sportvision.com/ SportVision
• http://www.pvi.tv/pvi PVI Virtual Media Services
• http://www.smartcomputing.com/articles/2001/s1212/17s12/17s12.pdf Computing Basics - How Did They Do That? Thin Yellow Line