It is likely that at some point, scrolling through a social network like Instagram or TikTok; you have come across a video in which a person was performing an interesting choreography, while around them, there was a kind of animated silhouette drawn that matched the person's movements. To learn how to replicate that effect professionally, you must understand how some After Effects tools and panels work.

Do you know how to activate the Brushes tool and how to set up its respective panel? If so, you already have the necessary basics to make a frame-by-frame animation. If not, don't worry. We will show you how to use them to animate the silhouette of a video character in After Effects.

How to set up a brush to make frame-by-frame animations on imported videos

To animate someone's silhouette, you first need to import the video you will be working on into After Effects. To do so, click Ctrl + I or Cmd + I and select the footage. 

Once you have the video you want to animate in your workspace, drag it to the layers below the Project Panel. This step is essential; otherwise, you will not be able to activate the Brush tool.

Once you activate the Brush tool (Ctrl + B or Cmd + B), adjust its properties in the Brushes panel (Ctrl + 9 or Cmd + 9):

1. Set your brush stroke by increasing or decreasing the pixels of the Diameter feature. Remember that the lower the value, the thinner the brush stroke. 

2. Define the color of your stroke by clicking Ctrl + 8 or Cmd + 8. This shortcut will open the Paint panel. Next, choose the color of your brush by selecting the shade in the main square next to the Opacity feature.

3. In the same box, there is a tab called Duration. Expand it and select Single Frame.

Outlining silhouettes in a single stroke for frame-by-frame animations in After Effects

After you have set the thickness, color, and duration of your brush, comes the fun part: choosing the frame you want to animate. To do this:

1. Go to the Timeline and hover over the exact scene of your footage.
   
2. When you have it ready, ensure your Brush tool is active.
   
3. Hold the click and outline the edge of the subject in a single brush stroke.

4. Switch frames by clicking Ctrl or Cmd + right arrow key and repeat the outline, but this time more separate from the character's figure. This trick will make it look like you are expanding a halo.

5. Continue changing the frame and making outlines more expansive and further away from the character, as in step 4, until you reach the end of the total area.

6. When you have finished drawing the lines, place the Time Indicator at the beginning of the Timeline and play the animation by clicking the space bar. And that's it! 

For more precise results, we recommend using a tablet and other After Effects tools, such as Zoom in and Zoom out, as you go through the steps. Remember that the more detailed the strokes are, the better the animated outline effect will look.