First and ten: the technology behind the Super Bowl broadcast

The low-tech NFL? Steaming bodies in the snow. Bone-snapping tackles. The stiff-arm. These are the iconic images of pro football, and they're low-tech in the extreme. While the game itself remains a contest of brute strength, raw speed, and little red challenge beanbags, the entire transmission infrastructure that brings the games into our homes and plasters them on our televisions in HD is exactly the opposite: millions of dollars of the most complicated broadcast technology on the planet. With the Midwest basking in the unseasonal glow of the Super Bowl spotlight, it's a fitting time to take a closer look at the tech that will power this Sunday's contest. CBS, which is covering the game this year, has deployed a crew of hundreds to Miami to man the HD cameras, run the first-down line, and show you the slowest of slow-motion replays. Here's a rundown of the equipment that will bring the game home. First and ten Consider the humble yellow line, now a staple of football broadcasts in the US. Companies like Princeton Video Image and Sportvision have developed and marketed the technology so well that it has a 98 percent approval rating from fans, and it's hard to imagine football without it anymore. The line is overlaid on the field to show how far each team has to go for a first down. It's the kind of effect that is immediately intuitive to viewers, and it looks like the sort of thing that should be simple to generate. Just slap a graphic on the field and be done with it, right? After all, networks have doing fancy computer-generated graphics for years, so a line would seem to be well within their capabilities. But the tech is is actually quite advanced. For the line to function properly, computers in the production truck must know exactly where the various cameras are pointing, how far they are zoomed in, and whether they are tilted at all. To make things worse, football fields are not entirely level, and players are constantly running back and forth across the line. In addition, the computer model of the stadium needs to be so accurate that the line can be projected within a foot or two of the official sideline chains. Making the system work requires several hours of pregame setup. Sportvision, for instance, takes a laser surveying system out to the center of the field, then uses it to precisely map elevations and contours. This information is used to create a detailed stadium model that is then passed to computers in the production truck. The cameras on the field are equipped with specialized sensors that measure pan, tilt, and zoom data so that the line can be properly projected and kept in the correct perspective as the camera moves. (This last requirement is also the reason why many replay angles do not include the line; it only functions with sensor-equipped cameras.) Out in the truck, techs use color keying to paint the line only on the field, not on the players. One palette tells the system what colors it can paint on, while another palette includes skin tones and uniform colors that cannot be painted on. Another operator is responsible for manually entering the first down yard line number whenever it changes, and the digital model of the stadium is then used to draw the line in the right place. Cablecam While cameras have been omnipresent at NFL games for decades, the "flying" overhead camera is a recent twist that enables broadcasters to provide views directly from behind the quarterback or from the middle of the defense—a view long-familar to fans of EA's Madden and NCAA Football franchises. Suspending a camera on guy wires doesn't sound particularly difficult, but it's hard enough to require specialized winches, gimbals, software—and Linux? Cablecam is one of the best-known of these suspended camera systems, and the company has provided equipment for both CBS and Fox broadcasts. The system they offer for sports events is a 100-pound assembly with an HD camera, a gyroscopic assembly to keep the camera level, and a fiber optic connection back to the control booth. Two wires, arranged to form an X, are strung the length of the field and then doubled back to their origin, where they are connected to winches. The camera is controlled by an operator who "flies" the camera around the field with a joystick while another person controls the pan, zoom, and tilt of the camera. A recent TV Technology article identified the Super Bowl camera on the Cablecam as the Sony HDC-F950, a $115,000, 3-CCD monster used only by movie and TV pros (though a recent Panasonic statement announced that Cablecam had just purchased a new Panasonic AK-HC1500G for use with A-list sporting events). Cablecam also announced a recent move to RTLinux from FSMLabs, an OS designed for real-time, mission-critical applications. "RTLinux was chosen for its reliability," said Cablecam head Jim Rudnusky. "It keeps personnel safe and ensures that the camera keeps flying when the game is on the air. The deterministic timing available from RTLinux is crucial to achieving smooth motor motion at high torque. The Cablecam application could not be achieved by anything less than a hard real-time OS." The camera's position is updated 200 times each second by the Overdrive motion control software, which runs on RTLinux, and control information is fed to a set of winches outside the stadium. The winches are driven by 20hp motors that can spin up to 3,000rpm and can position the camera anywhere in the field of play by reeling in cable and playing it out. The system is now sophisticated enough that an operator can fly the camera behind the ball carrier on a kickoff and follow his return up the field, all the way to endzone if necessary (and with Devin Hester running back kicks for Chicago, it may be necessary). Content from:http://arstechnica.com/articles/culture/firstandten.ars