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Roto-scoping wine bottle spinning on a lazy susan
Hello,
So I filmed a wine bottle against a green background so that I could key out the green and keep the wine bottle, but because the green was reflected against the glass of the bottle, it took away green from the bottle leaving what looks like a noisy image.
So, I decided to just rotoscope it out. The wine bottle is spinning in what should be the same place, so I figured it was one of the easier items to roto out.
My main problem now: There is a green line to show which frames are calculated/figured out (I think anyways), but I can’t get that green line to continue to generate. What do I do? See the picture attached.
Also, would you do this some totally different way? Fairly new to the professional side of video editing, and am eager to find out how to do things right first, and fast second.
Thanks a lot guys!
Paul Boone
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3 Replies
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I might use mocha to track the bottle’s movement and apply it to a mask. Better yet, simply create a bottle-shaped mask (using the pen tool) which is slightly smaller than the bottle, so you’ll mask away any green that becomes exposed during the rotation.
As for the right way to do it: any way you get it done is the right way! A lazy Susan is useful (unless Susan is your employee) but it’s hard to get the object on the precise axis of rotation. For a symmetrical object (in the y-plane) like yours, I might use a shaft attached to the bottle then connected to two supports (imagine an axle with a wheel that is actually the bottle). This is used in action films for flying, rotating arrows, bullets, spears, etc. and gets a perfect rotation. The support frame can be a sturdy cardboard box. The hard part is connecting the axle perfectly to the center of rotation of the bottle. Ideally, the actual body of the bottle can be used as the axle (not as illustrated here) then composite the shot.
Lowell Niles
Creative Director, Sunword Studios
https://sunword.com -
You really should be able to get a decent key off that image – I managed to get a nice clean one even off that JPEG (admittedly using a keyer I built myself). What are you using to try and key it?
Roto is not going to look good in a situation like this which is completely unforgiving of any inaccuracies.
Simon Ubsdell
tokyo-uk.com -
You could try to Auto-Trace the bottle, copy the mask onto a solid, and then use the solid as a track matte. If the bottle isn’t too far off the center axis, this could work.
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