As a football fan (OK huge GreenBay Packers fan) and one who has been in the creative, computer and entertainment space for some time I am sometimes asked how do they put that yellow line on the football field to show where the 1st down is? 

As if my limited knowledge of computer graphics would know – which it doesn’t.

In fact, this actually has baffled me for some time and it seemed much more complicated than simply ‘keying’ the color as they do during a weather cast with a map.

Well, it is much more complicated. I just read this article which tells the many components and steps it takes to present the “1st and 10” line.

Check out the full story here… http://entertainment.howstuffworks.com/first-down-line.htm