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Tracking position using perspective corner pinning (PB only)


    When you track position using perspective corner pinning, you are simultaneously tracking four points in a motion footage layer with four corners in a second layer. As the four points move, the layer is distorted to simulate perspective. The Tracker/Stabilizer applies the Corner Pin effect to the second layer, generating keyframes for the layer and Corner Pin-effect keyframes for each corner.

    As with affine corner pinning, you can place the track points for perspective corner pinning anywhere in the motion footage layer; they do not need to be in the center or in the corner of the feature regions. For example, if you are replacing a sign on the side of a moving bus, the edges of the sign may be partially obscured because of shadows or objects; but a window on the bus may be visible throughout the footage. You can first define four feature regions that are distinct and easy to track, and then move the track points to the four corners of the sign. When the new image appears in the sign, the Tracker/Stabilizer calculates the relative movement between the feature regions and track points to create the correct perspective.

    When you choose perspective corner pinning, the default positions of the track points form a rectangle in the center of the motion footage layer (left). Moving each feature region extends the rectangle in the direction of motion (center). You can place the track points anywhere in the motion footage layer (right).
    When you choose perspective corner pinning, the default positions of the track points form a rectangle in the center of the motion footage layer (left). Moving each feature region extends the rectangle in the direction of motion (center). You can place the track points anywhere in the motion footage layer (right).

    Fine-tune the motion of the individual corner pins within the Layer window by dragging the feature regions and noting the changes in the corresponding tracking coordinates. See Working with the Tracker/Stabilizer Controls (PB only) for details on tracking coordinates.

To define tracking regions for perspective corner pinning:

  1. Size feature and search regions on separate areas that you want to track in the motion footage layer. All four feature regions should lie in a single plane in the real world (for example, on the side of a bus, on the same wall, or on the floor). The four track points must also lie in a single plane, but not necessarily the same plane as the feature region.
  2. Place the four track points at the locations where you want to attach the four corners of the second layer. You can place the track points in the center, in the corner, or outside the feature regions.