[Shannon]

Do yourself a favor. Use as few point in your mask as possible. If you dont know how to manipulate the splines that make up the masks in AE, then read about all your options in help before you start.

Also, dont expect to use one mask for the hole thing. break it up. ie. one for her head, one for her torso, one for each arm. Sounds crazy but it will help keep it cleaner in the long run.

Others have given good advice when they mention keying the start and end frames first. What they mean is, make your masks perfect on frame one, then set a shape keyframe for them. Next go to the last frame and once again make perfection and set a key on shape. Now, go to the midway piont through the comp and see where AE has left your masks. Chances are the “head” mask is pretty close, but you’ll need to tweak others. Set a shape key. Now split up the first half and last half into quarters and do the same. Keep pairing down this way. This, as others have said, lets AE do a good portion of the work for you as it attempts to interpolate between keyframes.

Lastly, when placing the splines on your image, dither to just outside of the line of the subject to be masked, not on our inside the lines. Later you can contract and feather your masks a bit if needed.

You may be best off using the rotobezier splines which means just hitting that checkbox, and read help to learn how to control the hardness or angle on the points. Remember, USE ONLY AS MANY POINTS AS YOU NEED to describe your outlines.

With love, from a dude who lives the roto hell all day. Every day.