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Motion tracking for live action questions
I understand the concept of motion tracking and I’ve got AE CS5 and obviously Mocha to work with as well. What I need help with is the live action portion.
The concept we’re doing is someone walking with the camera (similar to the HP spots except the camera is moving backwards, talent walking in front maintaining equal distance) with an iPad facing the camera and the talent swiping through the screen. Their finger will move across the screen. My assumption is to use a rectangular green object with tracking points on it then track and key in the iPad.
Here are my questions, should I use an actual iPad instead? Do I need to use tracking points? If I do use an iPad, can I just put up a green image with tracking points or do I need to tape off the screen with chroma key green tape?
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4 Replies
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A JVC HM-700 with a standard ENG lens attached to a Varizoom Navigator.
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The great thing about Mocha is that you don’t need tracking points. It tracks planes, not points.
Check out this tutorial:
https://www.imagineersystems.com/videos/mochaimport-corner-pin-tutorial-for-after-effects-part1/view
Joey Foreman
Editor/Compositor/VFX Artist -
My camera shoots in a 4:2:0 color space. I’ve used it for key work before and the result was actually decent. Not incredibly perfect, but passable.
I tried using a prop. I took a piece of cardboard, painted it chroma key green, placed tracking points on it but when I tracked it in mocha, the tracking plane did not stay with the shape. The top X’s and corner of the board stayed in place but the bottom corners kept growing outward and made some odd shape.
I’ve done the search for motion tracking tutorials and tips, but all I keep finding are videos or articles that pertain to software, not how to set up the live action portion.
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I came across this tutorial and it did help me so I wanted to share it: https://www.imagineersystems.com/videos/how-to-shoot-for-planar-tracking/view
While it doesn’t cover everything, it does give a lot of information. Now it’s just a matter of trial and error and testing out different ways of doing this. When I find one that works well, I’ll be certain to share it.
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