Adobe After Effects boasts one feature that we cannot live without: the Motion Tracker tool. Applicable to a range of needs, we’re going to use it to stabilize footage, one of the easiest ways to add a professional touch to your work.
What Is the Motion Tracker in After Effects?
The Motion Tracker offers two functions at first glance: it can track the motion of the camera or the motion of an object within the frame.
This information is then used in one of several ways. The program may follow the tracker as it roves the scene with the help of a chosen anchor. Alternately, it may digitalize the path of the camera itself, allowing you to seamlessly trail off into a digitally-composited space.
Most commonly, the Motion Tracker tool is used to stabilize the footage ingested, either straight-up or through the use of the Warp Stabilizer feature, much like the one found in Premiere Pro. Here, we will focus on the former.
Choosing a Tracking Point in After Effects
The distinctive landmark in the video used to show the program what went down on set can be anything, as long as it pops from the background. It also shouldn’t disappear or fall out of frame at any time, even if only for the span of time that you need it for.
When tracking motion with the intent to anchor something digital into the scene, the pros anticipate the need for something that stands out readily. This is why they will often affix the source of the motion with some sort of marker.
You may want to block out the corners of a screen that you wish to eventually replace with brightly colored tape. Or, perhaps you’ll ask your actor to toss a neon tennis ball that’s standing in for something more exotic, like a terrifying ball of fire.
How to Use Motion Tracking in After Effects to Stabilize a Shot
To begin: fire up the program and pull in your footage. Create a new composition by hitting Ctrl + N. Drag your shot into the timeline.
With no layer selected, the entire panel will be ghosted. Don’t panic. Just select the footage in the timeline.
Bring the playhead to where you would like the program to begin its work; it can be at any point in the shot—you do not have to start at the beginning.
Hit Stabilize Motion. You’ll be given a Track Point to assign to some part of the shot, often called the Attachment Point.
We’ll go with the white tag on our friend’s forehead; it does not move from this spot and contrasts nicely with his terracotta complexion.
Pulling out the corners of the single “point” will actually reveal the fact that there are two boxes to contend with. Why is this so?
The inner box, called the Feature Region, should be scaled around the Attachment Point itself—in this case, the white tag. This defines your anchor point clearly to the program, helping it find the tracking element easily in each consecutive frame of the video.
The outer box, also known as the Search Region, limits the area that the program will use to search for the object defined in the Feature Region.
Making this area smaller will allow the program to render your results more quickly. A larger area of interest will make the process more thorough.
This is helpful for cases where the Attachment Point is not as distinct or is falling in and out of focus—not ideal, but it works in a pinch. If you know that you would like to use this tool, try your best to capture this element clearly and deliberately.
Analyzing Footage With the Motion Tracker Tool
Now, depending on whether the segment of footage that you need to stabilize falls before or after the playhead (you can do it either way), hit Analyze Forward or Analyze Backward.
Hands off the keyboard—the doctor is working. Let the program make its rounds, hitting the Stop button only when it has seen all that you wish to use.
You’ll be left with what initially looks like a string of keyframes. Impressive, but we’re not done yet. With your footage selected, hit Apply.
In this case, we want to take both the X and the Y axes into consideration. Select what you need and hit OK.
Closer inspection will reveal the keyframes addressing the issue.
Sometimes, you’ll have a wild hair here or there. Scrubbing through to the frame (or frames) in question will allow you to either adjust or delete anything that deviates wildly from what you’re after.
If smoothing out your footage proves to be challenging, pulling the keyframes up in the Graph Editor with Shift + F3 will give you a clearer view of the situation.
Here, we seem to be in pretty good shape. Any unusual peaks or valleys will become readily apparent and easier to manage.
You’ve Got It All at Your Fingertips With After Effects
The Motion Tracker tool ensures that you’ll never be left without the keystone shot that your film deserves. With a bit of creative footwork, minor technical setbacks like this become hiccups that are dealt with in no time.
