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AUGUST 06, 2003 AE6.0 Overview Part 3: Motion Tracking Even better than being able to stabilize a shot is the ability for After Effects 6.0 to track regions or points in a layer and apply that tracking information to another layer in your composition. With the tracking feature, it becomes a simple matter of making computer-generated graphics, effects, or even complex compositions follow a point in your video. The simplest type of motion tracking is to track a single point in a layer. As you may have guessed, this is very similar to tracking data for image stabilization that we covered in the last installment.[an error occurred while processing this directive]If you haven’t read parts one and Even if you didn’t read the last two installments, it is important to remember that the Anchor Point does not need to be located inside the Feature region box. The Anchor Point could be located outside the Feature region box because the area you want to place tracked layer could be a difficult area to get a solid lock. In this exercise, we’ll take some buttons created in Adobe Photoshop and track them to the tips of the subject’s fingers creating a futuristic/Minority Report-ish type interface. For this exercise, you can download the project files and project here. These are in .sit format and are quite large. Step 1: Create a new project (Option+command+N or Control+Alt+N) and import (Command+I or Alt+I) the video file and the button elements. The button elements are layered Photoshop files. Bring them in as separate layers.
Step 2: Create a new composition by clicking and dragging the trackpoint.mov clip to the Create New Composition icon in the Project window. If you look at the actor’s (i.e. ME) fingers closely, you will see red dots on the ends of the fingers. It is these dots that you will track the Photoshop buttons to. As a lucky twist of fate the actor’s fingers move so quickly at the beginning of the movement that the red dots are obscured until they reach the point where a button will be positioned. This saves us from having to digitally paint out the dots later on (although with the new Clone Tool this would be an easy fix).
Step 3: Scroll through the Timeline until the actor’s left hand is at a position where he appears to be clicking on a button (Command+G or Alt+G and enter 1:06 to Go To Time). Step 4: Position one of the interface buttons (in this case Purple Triangle Right) directly over the red dot on the actor’s finger. Make sure that the In point for the button layer is at the beginning of the Timeline, otherwise, the button will pop on screen.
For this exercise we’ll deal with just one button. Once you understand the tracking process, you can do the second track yourself.
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