Chapter7.Rotoscoping and Paint


Chapter 7. Rotoscoping and Paint

It's a small world, but I wouldn't want to paint it.

Steven Wright

So, you've gritted your teeth, girded your loins, and opened up the rotoscoping chapter. There's no way to paint an utterly pretty picture, so to speak, of the task you face: Rotoscoping and paint tools are generally a last resort, employed when there is no other way to fix your matte. Rotoscoping is the art of fixing a shot frame by frame, generally using masks. Cloning and filling using paint tools are variations on this task.

To compound matters, After Effects did not gain its fame as a rotoscoping tool. You can get good results with the program, but its interface and tools aren't set up expecting rotoscoping to be your main task, as they are in such dedicated programs as Curious gFx Pro or the no-longer-updated Pinnacle Commotion.

Although sometimes you just can't get around having to clean up footage by hand in After Effects, it's often not as bad as you think if you follow a few basic guidelines:

  • Ascertain that rotoscoping is definitely necessary. Novices and even pros sometimes will bite the bullet too quickly and assume it's time for frame-by-frame work without looking at other ways to break down the problem at hand. Specifically, make sure that these other tools won't help at least part of your problem:

    • Keying. See Chapter 6, "Color Keying," for more on using luma mattes (including matting footage with itself), color keys, and difference mattes.

    • Tracking. See Chapter 8, "Effective Motion Tracking," for more on the many ways to track in selections. Paint, by the way, is fully trackable.

  • Keep it simple. This is the number one piece of advice for any rotoscoping the world over. If you're articulating a mask, do it with as few points as possible. When keyframing that mask, use as few keyframes as possible.

  • Paint is a last resort. It is very hard to re-create realism with paint tools, and they will always be slower than masks. Assume that paint is an option only when you can't achieve a similar result with a mask. There are, of course, exceptions, such as cases in which you can easily track a paint stroke, and cases in which you're rapidly painting holes in an alpha channel.

  • Review constantly at full speed. Don't waste time heading down the wrong road. Carefully assess your footage via a RAM preview every few frames, and determine if your approach is working. If it's not, be prepared to switch tactics.

  • Combine strategies. Effective rotoscoping may employ a mixture of keying (whether color keying or a hi-con matte), tracking, animated masks, and paint. Start with the one that protects the most crucial edges, and work your way down to the cruder stuff.

A hi-con, or high-contrast matte, is created by taking luminance data from an imagetypically one or all of its color channelsand raising the contrast to create a luminance matte, typically to hold out areas of the same image. Chapter 6 explores this process in greater depth.


With these guidelines in mind and a solid grasp of the fundamentals of creating selections (remember Chapter 3, "Selections: The Key to Compositing"), you're ready to consider some rotoscoping specifics.



Adobe After Effects 6. 5 Studio Techniques
Adobe After Effects 6.5 Studio Techniques
ISBN: 0321316207
EAN: 2147483647
Year: 2006
Pages: 156

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