We also need something to apply the motion to. For this we'll be using what's called a Null Object. Basically an invisible object that can store information about position, rotation and scale. Rather like a Dummy in 3ds Max. To add one, right click an empty spot on the time line, choose New and Null Object (Fig.30).
With the Null in place, right-click the pyramid layer and choose Track Motion. A panel named Tracker Controls will appear on the lower right of your screen (Fig.31).
For this scene we need to track both Position, Rotation and Scale, so make sure all three boxes are checked. As it's hard to track rotation and scale with only one Track Point, an additional point will appear once you check them
Click the button called Edit Target and make sure it is set to our Null Object. This will make sure the motion data will be transferred to the Null Object when tracking is finished (Fig.33).
Now we need to decide whether we are going to track forwards or backwards. In our case, the tracking points (pyramids) are actually out of frame at the beginning of the clip, so we'll track backwards. That means scrubbing the time slider to the last frame (Fig.34).
Having chosen a frame, we need to align the Track Points with the pyramids. Click and drag one to the lowest corner of each pyramid. We're choosing the lowest points as they are the last parts of the pyramids to exit the frame before they disappear completely, which gives us another couple of frames of tracking (Fig.35).
Now press the Analyze Backwards button and watch After Effects tracking the scene. As you can see, the pyramids disappear after a while, making the Track Points stop, but after that point we don't see the horizon anymore and as the point here is to track the sky, that's perfectly acceptable (Fig.36 & Fig.37).
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