"Yellow" first down marker

After watching MNF last night this question occured to me. I am sure that anyone watching American Football has noticed that there is now a superimposed first down marker that only the TV audience can see. It looks like someone with a big yellow crayon drew down the middle of my TV screen so we can all see where the ball has to cross to make a first down. So my question is; how is this done?

A LOT of effort goes into making that little yellow line Cheese.

Here is a brief summary:

Wow, Spit, you werent kidding. That is a lot of info!! Thanks

Try this page for the answer. It sounds like it’s mostly sensors to tell the camera where it’s pointing and then geometry to draw the line.


Oops. Here’s the page.

I don’t know if they’ve improved the technology in the past year or two, but the next time that Green Bay or Philadelphia is playing, watch the uniforms. The line gets superimposed over anything green, not just the field.

Maybe my memory is playing tricks on me, but it seems to me that the yellow line used to be more realistic-looking. In previous seasons it looked almost like it was actually painted on the field, but this year it’s a lot brighter and fake-looking. I wonder if that was done on purpose because they were getting tired of people thinking it was really there.