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On major film productions greenscreen have white dots?

Discussion in 'Fan Films, Fan Audio & SciFi 3D' started by Lukemax, Jun 18, 2008.

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  1. Lukemax

    Lukemax Jedi Youngling star 1

    Registered:
    Aug 1, 2007
    Hi all, On major film productions, you sometimes see the greenscreens they use have white small dots on?

    Why is that?, somekind of marking i assume?

    Lukemax
     
  2. darthviper107

    darthviper107 Jedi Master star 4

    Registered:
    Jun 26, 2003
    Camera tracking. They need reference points to track the movement of the camera so that any CG environment will be matching the camera motion.
     
  3. erus_multus2

    erus_multus2 Jedi Youngling star 3

    Registered:
    Nov 11, 2005
    Yeah, my sister saw me working on some greenscreen footage the other day and asked me that. I tried explaining it to her, but she just did not understand.

    Maybe I was just explaining it badly.

    But yeah, they're there as a fixed point relative to the camera so that you can track their motion as the camera moves.
     
  4. bobaandy123

    bobaandy123 Jedi Master star 3

    Registered:
    Jan 21, 2005
    Interdimensional beings, actually.
     
  5. Penitio

    Penitio Jedi Master star 3

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    May 11, 2002
    I've done some greenscreen work without those markers. It's insanely difficult to match camera movement without those markers. They shook the camera like an explosion hit, and I was like "GRRR". Put the damn tennis balls/dots/black and white squares up. TWO at the very least. The more the better.
     
  6. Lukemax

    Lukemax Jedi Youngling star 1

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    Aug 1, 2007
    Hmm interesting, I would like to read on thoe, is there anywhere tutorials wise or maybe somewhere that explains it better?
     
  7. Vidina

    Vidina Jedi Master star 4

    Registered:
    Jan 11, 2006
    My Greenscreen tutorial explains it a bit.
    In short, the points around the screen is for motion tracking. This means that if the camera should move during the shot, you have reference points to match the movement from. Example: your own background is just an image. However, during the shot, the camera moved slightly, meaning your actors would move on the new background, without the background moving at all. 'twould look weird.
    The points are for your application's motion tracking system. You select the point with a tracker, and the tracker does it's job. After that, you apply the tracking data to a null object, and set your background(the one to replace the green screen with) as a child to that layer. Alternatively, you could use expressions(explained in detail in the tutorial).

    Hope that cleared up things a bit more.

    -Tom.
     
  8. Lukemax

    Lukemax Jedi Youngling star 1

    Registered:
    Aug 1, 2007
    As soon as i saw Vidina had replyed, i knew i had my answer, Thank you!
     
  9. Vidina

    Vidina Jedi Master star 4

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    Jan 11, 2006
    Hah.
     
  10. maul2

    maul2 Jedi Master star 2

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    Aug 1, 2005
    Alright this is one thing that has kinda confused me. Won't the white dots not get keyed out?? I mean they arn't green (or blue or whatever color you use) so won't there be like all these random floating dots in your shot. re they just so small that they get wiped out and the camera doesn't se them? Or do you have to go in and mask them out??
     
  11. NateCaauwe

    NateCaauwe Jedi Grand Master star 4

    Registered:
    May 30, 2005
    Generally you have to take time to remove them. However, using yellow tracking markers sometimes helps, as it contains green and can be keyed out easier. But for the actual tracking you just use the red channel. Yellow is half red, green has no red, so you essentially get white markers on a black screen. In any case you should be garbage matting around your actors anyway, so you'll just have to worry about the markers that get close to them.
     
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