In this walkthrough, we've shared how to rotoscope in After Effects, so you can transform live action video into gorgeous animations.
What is Rotoscoping?
At the most basic level, rotoscoping is isolating a subject from the background. With the advent of editing software like After Effects, artists have taken that simple concept and explored a variety of creative directions. With built-in After Effects tools like the Roto Brush, it's fairly easy to draw outlines around your subject and create a cartoon-like effect. This is what most people think of when they hear the term "rotoscoping", and it can be used to trace extremely detailed animations.
How to Rotoscope in After Effects
1. First, load your current After Effects project and choose a clip that you'd like to rotoscope. Then, select the Roto Brush by pressing Alt+W (or Option+W on Mac).
2. The Roto Brush works a lot like the Quick Selection tool in Photoshop, in that you can draw a rough outline around the image, and then After Effects will analyze that area and determine where the subject meets the background. Anything you draw with the Roto Brush appears in bright green, and then it disappears and is replaced with a thin pink outline around the selection.
3. As you continue to draw with the Roto Brush, the pink selection will expand until it isolates your entire subject. Next, you can train the Roto Brush to avoid selecting the background by holding the Alt key (Option on Mac) and drawing on those areas. While the Alt key is pressed, your Roto Brush strokes will be bright red.
4. As you start to play the clip frame-by-frame, you'll see that the Roto Brush outline moves in sync with your subject. It's a good practice to scrub through the clip before making any more adjustments to the project, just so you're certain that the selection stays consistent. At any point, you can pause on a particular frame and tweak it with the Roto Brush.
5. When you're happy with the Roto Brush selection throughout the clip, go back to the Composition view. The background should turn black, leaving only your selected subject. This may look a bit sharp or unflattering around the edges, but you can smooth it out by turning on "Refine Matte" under the Roto Brush settings. This adds subtle blending to your selection.
Now that you've isolated a subject using rotoscoping, you can apply all sorts of amazing effects, such as illustrating the subject, changing the background, and much more. Once you let After Effects take care of the technical details, you'll have more time to focus on the creative process.