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RotoScoping Versus Masking

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Lou WilliamsRotoScoping Versus Masking
by on May 9, 2013 at 10:47:22 am

I have scene that I am working on. It's the interior of an airplane and I need to replace what is currently being seen outside the airplane window. In the scene passengers arms are in constant motion across the window. I am pretty sure I can use a mask and change the shape frame by frame, but I was thinking about rotoscoping since those tools seem to be able to create an outline pretty quick with just minor fixes between frames. However rotoscoping seems be for cutting out the outline area I need it to exclude that area. I am pretty new to AE and rotoscoping in general, so I am not sure this is correct way to use this tool. Is this a good approach? Any suggestions would be a help. Thanks.


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John CuevasRe: RotoScoping Versus Masking
by on May 9, 2013 at 12:58:40 pm

I find I get a little frustrated using masks to rotoscope and generally prefer the rotobrush to do this type of work. The rotobrush isn't that intuitive though and I'd suggest you take a look at some of the tutorials and information about it before you start. I think this one is really good:

AfterEffects CS5: RotoBrush

Take a look and if you have more questions get back to us.

Johnny Cuevas, Editor

"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.

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Dave LaRondeRe: RotoScoping Versus Masking
by on May 10, 2013 at 6:05:37 pm

I suppose this shot is in the can with no chance whatsoever of re-shooting. That's too bad.

You could have saved yourself a lot of trouble by putting a green screen background in those windows and using Keylight.

Now, it not quite as simple as it sounds because you must make sure the background is lit evenly, and is at hease two stops darker than portions of the shot assumed to be white.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA

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Lou WilliamsRe: RotoScoping Versus Masking
by on May 10, 2013 at 7:28:06 pm

Unfortunately can't reshoot and they did not use green screen. The shoot was done at night with a real airplane. So to get the cabin well lit they placed white material over the outside of the fuselage covering the windows along with a white back drop by the cabin door and backlit everything with massive flood lights. It diffused the light but the color is not pure white, so I can't key on it. I am thinking about using mocha pro, or may have to resign self to painful frame by frame masking.

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Robert HeadrickRe: RotoScoping Versus Masking
by on May 14, 2013 at 2:25:00 pm

If it's at least close to pure white, you might be able to treat it like a sky replacement and do it with track mattes. Duplicate the layer, convert to black-and-white, adjust contrast to blow out the window, mask out the rest of the shot (masking the window will be infinitely easier than masking the moving arm!), then use this layer as a track matte for the original clip.

That's off the top of my head; this may or may not actually be a good technique in this situation. I just got The After Effects Illusionist and was reading about channel effects, color correction, and track mattes the other day, so it's on my mind. :-)

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