Sunday, November 13, 2011

Apple #558: Aerial Cable Cameras

This topic seems like bad timing, given the recent news about the Sandusky/Penn State nightmare. But I was asked to find out about how skycams work before that whole story broke, and in spite of my horror and disgust at that news, I discovered over the weekend that I do still like to watch football. Probably many of you out there do too. So I'm going ahead with this.

Specifically, longtime Daily Apple reader Demarcus wanted to know, how does the camera that flies over the football field work? He said at the last football game he attended, he'd noticed wires coming from each of the four corners of the stadium, and that the camera hung from the nexus of those four wires. Beyond that, he couldn't really figure out how it works.


The Skycam travels along cables over a football field to provide aerial images of the game in action.
(Photo from Wired)


This video below shows examples of the kinds of shots that are possible with these aerial cameras. In this gane, the camera used is called a SpiderCam.



  • These aerial cameras are typically referred to by the brand name Skycam, but there are lots of brands and manufacturers who make aerial cameras. Another common one is Cablecam.
  • [side note: Skycams are not to be confused with SkyCams which are stationary cameras mounted on tall buildings and other various key locations around the country and which are used to photograph weather events.]
  • Whether it's a Skycam or a Cablecam or some other aerial cam, they're set up in essentially the same way, with three major components.
  • Component 1. The wires or cables. The cables are made of very sturdy braided Kevlar. There are four of them, as Demarcus correctly noticed, and the camera hangs where the four reels intersect. The cables extend to each corner of the stadium, runs through a pulley and down to a reel and winch. Because of the cables, the camera systems are sometimes called cable cameras.
  • Component 2. The camera itself and the on-board motor and controls. The most recent version of hte Skycam uses a Panasonic AK-HC900 2/3" IT CCD camera, which is an HD camera that, in 2004, cost around $35,000.
  • Above the camera is a box that includes motors that allow the camera to pan and tilt, various electronics, and Steadicam stabilization sensors. A fiber optic cable carries the signal from the camera up to the central control (component 3). The camera and the black box together are sometimes known as the mobile spar.
  • The mobile spar is three feet tall and weighs somewhere between 25 and 45 pounds. It can whiz along the cables at speeds up to 40 mph.


A Skycam, as of 2006. Inventor Garrett Brown was awarded an Oscar for making this.
(Photo from GizmoWatch)



On the Cablecam, the box with the motor in it is flatter and more rectangular than the Skycam. This Cablecam also has a microphone attached to the bottom of the camera.
(Photo from Sports Video Group)


  • Component 3. The rest of the system is up in the booth, or somewhere remote from the camera. This is the computer which tells the camera what to do, and may be referred to as central control. Most of this system runs on Linux, or a version of it (specifics about the operating system have continued to change as the technology improves, but this is still generally true).
  • Two people control the system. One person operates a computer which directs the camera itself, adjusting the lens, its tilt and focus. Another person, the pilot, directs the reels to tighten or loosen the cables as necessary, thus moving the camera system over the field. The pilot watches a rendering of what the camera is doing on a computer screen and directs the reels using a mouse.
  • Initially, the system was controlled using a joystick.
  • [side note two: I find the use of the joystick pretty interesting, since the idea to use the above-the-field-camera in football came from video games. One guy who pilots the camera for his job says, "it's tricky. . . . It's like a video game."]
  • [side note three: the superimposed on-screen yellow first down stripe is another idea that came from video games. I agree with my dad, that this is one of the best improvements to television coverage of football games maybe ever.]





I really wanted to find a diagram of the black box where the camera motor is housed so I could see how those innards work. The best I could find was this schematic from Cablecam, which describes lots of pieces of the system, but in a fairly general way. It's hard to see much of the detail at this size, but you can see it better at this larger size, which especially helps in reading about how the winches and reels work.
(Diagram from Cablecam, hosted at Free Image Hosting)




A reel and winch controlling the cables in a Skycam system.
(Photo from Digital Producer Magazine)


  • The systems have multiple built-in back-up plans so that if a reel does snap, another one is there to catch the camera or a program is in place to move the camera out of the way.
  • But on at least one occasion that I know of, the Skycam actually did malfunction and drop to the field. This happened during a Saints-Seahawks game in 2007. Play was stopped and the network looped a whole bunch of commercials until someone got the camera fixed.


Skycam way too close to the field in this football game in 2007.
(Photo from Awful Announcing)


  • The whole system is constructed so that neither the spar nor the reels should interfere with play. But the aerial camera does sometimes make its appearance in shots of the field taken by other cameras, which some viewers find annoying.
  • It also happens sometimes that players will look up at the aerial camera and smile and wave or otherwise play up to it.
  • The guy who invented Cablecam and who was often on the field before the game helping with set-up, said that during warm-up, kickers often try to kick the ball so that it will hit the camera.
  • That was in 2005, and I don't know if anyone's succeeded in hitting the camera yet. I hope someone does, as that would be an achievement with major bragging rights.
  • As of 2005, it cost about $40,000 to $50,000 to use an aerial camera per game. Costs may have come down a bit since then, but man. That's a lot of money for one camera in one game.
  • The aerial cable camera was invented in the 1980s, but its uses were limited due to limitations in the computer software. In the 1990s, it was used more often and in more applications. In the SuperBowl in January 2001, it entered the world of football as EyeVision. The aerial cable camera's fortunes have only gone up from there.
  • Its use has spread to other sports and other venues. It's now been used in tennis, hockey, boxing, soccer, Major League Baseball, the Olympics, X-games, ice skating, swimming, bowling, even the Running of the Bulls in Pamplona. Lots of film crews have also used aerial cable cameras to help them get a specific shot, in movies, TV shows, and commercials. It's even been used at the Academy Awards.
  • Today, Cablecams and Skycams are used in about 200 events each year.


Photographer Emanuel Schwermer using a cable cam to film a car for a commercial.
(Photo from Emanuel Maximilian Schwermer's site)



More resources:

Two-page spread detailing all the types of cameras used in a professional football game.

Photo showing how the cables are attached to the roof of a stadium.

How the yellow, superimposed first-down line is done.


Sources
Henry Fountain, "A Chance to Peek Over the Quarterback's Shoulder,"
The New York Times, January 6, 2005
Eric Gwinn, "Working the angles,"
Chicago Tribune, November 11, 2004
Monday Night Football: Behind the Scenes, Digital Producer Magazine, December 3, 2004
Michael Hiestand, "Suspension sends Irvin Message," USA Today, December 1, 2005
Greg Wyshynski, "Chatting with NBC Sports Executive Producer Sam Flood about Winter Classic," Yahoo! Sports, December 21, 2010
Cablecam, What We Do
Skycam, skycam in action

3 comments:

  1. OK, but it still doesn't assuage my fears about the cable flying through the stands and decapitating me!

    ReplyDelete
  2. That is so awesome, I'm an avid photographer, so this is one of the coolest things I've read about. Though I'm with Jarred, I'd still be nervous about snapping cables (at least the really long ones!)

    ReplyDelete
  3. Good effort.It help me a lot in understanding Spidercam.thanks!!

    ReplyDelete

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