That little yellow line challenges everything I know about television production! How does it work???
In a newscast, for example, an image that doesn’t really exist can easily be shown on the screen. It’s called a keyed graphic and often takes the form of a lower third (e.g., those words on the bottom of the screen giving the reporter’s name and location). So we can easily have two images: one real, and one existing only on viewing screens.
Well and good, but the yellow line ain’t that!
During a newscast, the keyed graphic is added to the scene the camera is shooting, so it covers up the live shot. But during a football game, the opposite happens - the live shot (the players) cover the yellow line as if it were physically on the field!
Now, a keyed graphic can be made semi-transparent so that both it and the real scene show through, but that is definitely not what’s happening with the yellow line. There’s not even a faint ghost image of it going through the players, as there would be if it were simply a semi-transparent keyed graphic.
I realize stuff like this happens all the time in movies. It’s the bedrock of cool special effects. But effects like these take thousands of hours of postproduction time; the football game is shown live.
So how does Princeton Video do it in real time???
~ Complacency is far more dangerous than outrage ~