Just a couple weeks before the Superbowl, here’s a video that breaks down the technology behind the yellow first-down line on TV broadcasts for American football.
It’s a live compositing system that reads live camera position data from each camera on the field and draws the line over the video feed through some color filtering which masks out the players. I was struck by the simplicity of the engineering, using a spare audio channel from each camera to carry camera position data.
