Adobe AFTER EFFECTS 7.0 - Page 351

ADOBE AFTER EFFECTS 7.0
User Guide
345
See also
“Corner Pin effect (Pro only)” on page 423
To track motion using either parallel or perspective corner pinning (Pro only)
To track motion using either parallel or perspective corner pinning, you select the layer and adjust settings in the
Tracker Controls panel. When you track motion using either parallel or perspective corner pinning, After Effects
scales and skews the target layer as necessary to fit the dimensions defined by the feature regions.
1 Select the layer you want to track in the Timeline panel.
Note: The selected layer must include motion or changing frames, such as video source footage, for Track Motion to be
available in the Animation menu. If you want to track motion in still images or a sequence, first pre-compose the layer
by choosing Layer > Pre-compose.
2 Choose Animation > Track Motion or click Track Motion in the Tracker Controls panel. After Effects then
performs the following actions:
• Displays the Tracker Controls panel with the selected layer listed for Motion Source.
• Adds a track point for the motion source in the Layer panel.
• Adds the new track to the Motion Trackers section of the motion source layer in the Timeline.
3 Click Edit Target in the Tracker Controls panel and choose the Motion Target layer from the Layer pop-up menu.
4 Choose either Parallel Corner Pinning or Perspective Corner Pinning from the Track Type menu. Four track
points appear in the Layer panel. (For Parallel Corner Pinning, one point is inactive.)
5 If you want to track a range of frames, define the work area you want to track in the Layer panel for the source
footage.
6 In the Layer panel, move the current-time indicator to the frame from which tracking should begin.
7 For parallel corner pinning only: To change which point is inactive, Alt-click (Windows) or Option-click (Mac
OS) the feature region of the point you want inactive. (One point must remain inactive to keep the lines parallel.)
8 Using the Selection tool, place and resize the feature and search regions over the areas you want to track. The
featureregionsshouldlieinasingleplaneintherealworld—forexample,onthesideofabus,onthesamewall,or
on the floor.
Note: The search region needs to be only big enough to accommodate the frame-to-frame position change of the feature.
9 Placetheattachpointsatthelocationswhereyouwanttoattachthecornersofthetargetlayer.Theattachpoints
should also all lie in a single plane, but not necessarily the same plane as the feature regions.
10 In the Tracker Controls panel, click either the Forward Analyze or Backward Analyze button to begin tracking.
Watch the tracking to make sure that it is accurate. If not, click the stop button to stop tracking, and then correct the
problem as described in “Correcting a drifting feature region (Pro only)” on page 346.
11 When you are satisfied with the position of the feature regions throughout the footage, click the Apply button to
apply the corner pinning track to the specified target. After Effects creates Corner Pin effect keyframes for each
corner and copies them to the target layer.
See also
“To set a work area” on page 121