Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Digital imaging: first down line in football

  1. Sep 27, 2010 #1
    I was asked how the artifical colored line now used in pro football games to mark the first down line is placed behind players and other images. And could not.

    In other words, print overlays, say with team names and scores, block the underlying field images...but somehow the artifical first down line is placed behind regular screen images ...so when a player runs over the artifical first down line, for example "painted" on the field, the leg of the player remains visible as he passes over the first down line image...How do they accomplish this "3 D" sort of overlay??
  2. jcsd
  3. Sep 27, 2010 #2


    User Avatar

    Staff: Mentor

    The field is green - the technology is the same as a greenscreen.
  4. Sep 27, 2010 #3
    I've always wondered, what about the Packers? They're green too. How come they don't become the first down line?
  5. Sep 27, 2010 #4
    Russ...what is greenscan??...never heard of it...no hit in wikipedia...
  6. Sep 27, 2010 #5


    User Avatar
    Science Advisor
    Gold Member

    It's greenscreen not greenscan.

    http://en.wikipedia.org/wiki/Chroma_key" [Broken]
    Last edited by a moderator: May 4, 2017
  7. Sep 28, 2010 #6
    Don thanks....
    odd that the Wikipedia search engine can't suggest 'greenscreen' for 'greenscan'....a 'greenscreen' search entry immediately turns up your refrenced page.....
    Last edited: Sep 28, 2010
  8. Sep 28, 2010 #7


    User Avatar
    Gold Member

    Does your local weatherman have active radar displays, updated temperatures and wind speeds, etc on maps behind him? Same technology.
  9. Sep 28, 2010 #8


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Weird that the initial work on picturing inlaying on TV used to use a blue screen. They suddenly appeared to change the switching colour. Why was this? Could it have been because of the need to work out of doors for large scenes?
  10. Sep 30, 2010 #9


    User Avatar
    Science Advisor
    Gold Member

    For what it's worth, it's common to see a team with similar colors in their unforms that the line will show up on.

    What's interesting to me is that the line stays in the correct spot even if the camera is randomly panning or zooming after a player. I've always wondered how they do that...
  11. Sep 30, 2010 #10


    User Avatar
    Science Advisor
    Gold Member

    Ask, and you shall receive:


    Last edited by a moderator: Apr 25, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook