4-Point Tracking			Correcting Errors
Chapter 25, Tracking and Stabilizing

Topics on this Page:

Positioning the Tracker Box Manually

Tweaking the Tolerance Value

This section provides different strategies that you can use to track difficult shots.

Positioning the Tracker Box Manually

When the reference point is temporarily covered by another object, position the tracker manually.

1. Click the Analyze Forward button to stop the analysis.

2. Advance the clip to the frame where the reference point becomes visible again, and reposition the tracker box over the reference point.

3. Click Analyze to restart the analysis at this frame. Since the X and Y shifts are recorded as keyframes in channels, the translation values for the frames in which the reference point was covered are calculated. The final result will be a smooth motion.

Tweaking the Tolerance Value

The Tolerance value determines how exact a match the Stabilizer requires when identifying the reference point. With a tolerance of 100%, the Stabilizer accepts anything as a match. With a tolerance of 0%, the feature being tracked must be exactly the same as the reference point. If a match is not found, a keyframe is not set, and the position of the reference point is interpolated between the previous keyframe and the next keyframe.

If the reference point is temporarily hidden by another object, you can use the Tolerance value to make the tracker ignore the reference point in parts of the clip where it is hidden, then continue tracking it normally when it reappears. This can prevent or reduce the need to manually reposition the tracker box during an analysis.

1. Analyze the footage with full (100%) tolerance.

2. The tracker loses the reference point when it is hidden. Press Backspace to delete keyframes and go back to the last bad keyframe. Lower the Tolerance value until the cross hair disappears from the tracker box. The keyframe at that frame is deleted. The cross hair indicates that a frame has a keyframe.

3. Click Analyze to continue the analysis. Further analysis automatically discards the undesirable keyframes, and the position of the reference point is interpolated until the reference point reappears.