AUGUST 04, 2003
AE6 Overview Part 1: Tracking and Stabilizing Motion
One of the things that can plague even the best of videographers is a shaky camera shot. I always try to stress the importance of using a tripod when shooting, but because of the nature of the shoot (or people ignoring good advice) not using a tripod could be a necessity. This could lead to a great take ruined by a wobbling camera. Time and budget may not allow the production crew to go back for a reshoot, so what do you do when the producer is screaming for a nice stable shot?
The Tracking and Stabilization features have been a staple in the After Effects Production Bundle for some time, but it wasnít until 6.0 that improvements to the system have made working with this feature a snap.[an error occurred while processing this directive]Before we get too far into the improvements, I probably should discuss the difference between motion tracking and image stabilization. On the most basic level, both processes acquire the necessary data by tracking pixels or areas in the target footage. While the tracking procedure is similar for both, what each does with the data is quite different.
If you need to stabilize footage, Adobe After Effects uses the resulting data to adjust anchor and rotation positions.
For example, if the region you are tracking moves to the left 10 pixels in one frame, After Effects moves the anchor point (position data) for that one frame to the right 10 pixels. In the next frame the tracked region moves up 5 pixels, and Adobe After Effects adjusts the anchor point by moving the frame down an equal amount. This process continues frame after frame until the end of the clip. The result is that every single frame of the video layer will have a new anchor point keyframe.
When the feature for motion tracking, After Effects takes the tracked data and applies the information to other layers in the Timeline. Motion tracking can use a single tracking point that could be applied to allow a CG butterfly to follow the movement of a practical flower. After Effects 6.0 can also motion track using three or four points to properly corner pin an image to the side of a building.
The Motion Tracker and Stabilization feature can only be accessed once a clip is in the timeline. Once there, there are a couple of different ways to gain access to the feature.
One way is to Control+Click (right click) on the layer in the Timeline and select Track Motion or Stabilize Motion. The other way you can access the tracker or stabilizer is from the Animation menu.
Once you have selected one of the methods, the clip will open in itís own Layer Window and the Tracker Controls Palette will appear.
Regardless of whether or not you are tracking data or stabilizing footage, the core functions of Motion Tracking and Stabilization are the same.
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