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Green Screen/ Compositing

edited April 2011 in iStopMotion for Mac
Has anyone here had any luck using this? We have had several attempts, each time ending in frustration and failure. We have tried different lighting setups, and different coloured backgrounds, each time trying to get the most tonally even background, but we have never succeeded in adjusting the colour sensitivity so that all the background is successfully selected, without some parts of the foreground figures also disappearing into the background.

Is there some trick we are missing, or is this just too difficult for a hobbyist filmmaker without a big professional lighting rig, or is this just a software problem, that is to say, it just does not work?

Comments

  • Hi James,

    I am sorry to hear that you have troubles with our chroma keyer. Indeed, Green Screening is not easy.

    My guess is that what you see is that the object reflects part of the background. Here are a couple of tips:

    1) Put the green screen as far back as possible.
    2) Use far less light on the green screen background than you do on the foreground object. It is not important that the green screen is especially bright just that it is evenly lit just enough.
    3) Use a special green screen cloth or green screen paint. There is a special color that works best for green screen.
    4) Avoid colors in the foreground object that are close to the green.

    You might also want to do the green screening in a post production software such as iMovie after you've captured the clip. The chroma keyers in those packages may produce better results. We designed iStopMotion so that it preserves the original shot without the key applied (we just add an alpha channel) so you can use the built-in chroma key to get a preview while shooting and use the post production tool to do the final compositing.
  • thank u its very helpful
  • Oliver,
    Thank you for this forum. I enjoy several Boinx products.

    Re. compositing: has anyone perfected the "image key" concept where, instead of a constant chroma, the background is a complex image which is the key to creating the alpha channel? Apple toys with the concept in their PhotoBooth and iChat apps but doesn't work very well.
  • Thank you very much for your tips Oliver. We will have another go.
  • @dcrellen: We looked into the image key concept. But it is tough to do since even tiny movements in the camera can screw it up significantly.
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