Autodesk 62205-051408-9001 User Guide - Page 709

Tracking Combinations of Position, Scaling, and Rotation ❚❘❘ To track changes in rotation only: 1. Determine a good reference frame and position the clip at that frame. 2. Select the object to which you want to apply the rotational changes. Make sure the pivot point for the object is where you want it to be. 3. In the Tracker panel, select the Source of the reference feature. 4. Click Rotate. Two Trackers appear. The first Tracker appears over the pivot point of the object and the second appears to its lower right. 5. Position the reference box of the first Tracker over the pivot point of the rotation you want to track. 6. Position the reference box of the second Tracker over the area which describes the arc of the rotation you want to apply to the object. 7. Adjust the settings for each Tracker as necessary. 8. In the Tracker panel, click Select All Trackers, and then click one of the Analyze controls to start the analysis. The object rotates at its pivot point at each frame to reflect the rotation defined by the motion of the two reference features. 9. Pause the analysis, make adjustments, and restart the analysis as necessary until the analysis is complete. See Advanced Tracking Techniques. 10.Save the Tracker data if necessary. 11.Click the Off button in the Tracker panel when tracking is complete. Tracking Combinations of Position, Scaling, and Rotation It is also possible to track any combination of position, scaling, and rotation. To do so, you always work with two Trackers. As you combine tracking operations, you add to what each Tracker is tracking. If you want to track position, rotation, and scaling simultaneously, the first reference box tracks position. The second reference box tracks rotation. The distance between the centers of the two reference boxes is used to track scaling. Tracking Multiple Points When you track multiple control points, you apply the motion of each reference feature to control points on the foreground object. The shape and content of the object changes to reflect the motion of the reference features it is tracking. For this reason, a precision track is required, as even small drifts will cause any lettering or graphics on the front clip to "swim" or "crawl". For example, you can put a new label on a pair of jeans. You create a new label, then have each control point on the new label track one of the reference features of the old label. The shape of the new label changes with the shape changes of the original. This example is similar to the example for tracking position (see Tracking Position) except that the new label is a layer instead of a Paint object, and the four corners of the label are tracked for more precision. To track multiple control points: 1. Play the clip a few times to evaluate what reference feature you want to use and if there are any foreseeable problems for the tracking. See Finding a Good Reference Feature. 2. Determine a good reference frame and position the clip at that frame. 693