Spring 2013 TEMPO - Tampa Preparatory School

29alumni newsFall Convocation Addresskathryn johnson koehler ’91Thank you for your introduction and askingme to speak this morning.How many of you know about thatyellow line on the field when you watch afootball game on TV? Do any of youwant to hazard a guess as to how it’sdone?You wouldn’t believe the answers I getto that question. Some people think it is alaser built into the field. Others think wehave a magic pen and draw it on thecamera before each play.I’ll let you in on the real story.The yellow line is essentially one ofthe earliest forms of augmented reality.First, we determine where the camera ispositioned relative to the field. This isaccomplished by aiming the camera atthe field, feeding the video through oursoftware and clicking on the yard linesand other markers to record their position.With that information, we are ableto construct a virtual field in our system.Second, we determine where the camerais pointing. On the camera, we have adevice to measure pan, tilt and zoom orptz—the movements performed duringfilming. Using ptz measurements, thedigital field model and some fancy math,we can derive where the line should bedrawn and place it in the broadcaststream. Before each play, our line operatorssimply punch in down and distanceinformation. Our software does the rest.Finally, we use chroma keying, a techniquethat alters an image based on colorhue, to distinguish between what is grassand what is a player. The goal is to createa realistic illusion that “chalk” is actuallyon the field. That way we don’t get funkylayering and wind up breaking the illusion.This is the same technique you use inyour green room but unlike the constantsolid green color, grass is tougher to distinguish.It can be white, green, brown,depending on surface type, time of dayand weather conditions. To address this,our operator determines what colors tomask throughout the game by selectingsamples of the field on video. Oh, and allof this happens live, of course! Pretty cool.The yellow line and a host of otherwell-known sports broadcast effects arewhat drew me to Sportvision. I am ahuge sports fan and it’s a nice perk to beable to work your passions. I spend themajority of my time managing the developmentof Web and mobile applications.We’ve partnered with nascar to producereal time products. What I mean by realtimeis that we have instrumented everyracecar with military grade gps (GlobalPositioning System) and imu (InertialMeasurement Unit) systems. Thesedevices deliver 3Dimensional positioningdata for all 43 cars, 5 times a second withan accuracy of +/- 2 cm. Not only do weknow position, from that data, we canderive mph, braking rate, time off leader,pit stop information, left jack, right jack,etc. It is mindboggling. We then renderthe positional information in a virtualworld both on the Web, and on mobiledevices and tablets using a 3D gamingengine. Imagine watching any car in therace from any camera angle at any pointin time, live.continued on page 31Convocation speaker Kathryn Johnson ’91and Mr. Shepley