Tracking a Mask

You can track a mask in your scene from the GMask object's Tracking tab. You can track the mask vertices using the Tracker, or track shapes using the GMask object's own shape tracker.

To apply shape tracking to a mask:

1. Select the mask you want to track.
2. Open the Tracking tab.
3. Under Shape Tracking, set the Use Media field to assign the front and matte clip.
4. Under Tracking, adjust the fields as needed.
5. Select an option from the Track Direction box to determine if the frames before or after the current frame will be used for analysis.
   TipWhen tracking a shape that cuts off during analysis (for example, a person walking into or out of the frame), begin shape tracking when the whole shape is apparent, and track in the direction of the frames at which the shape begins to disappear.
6. Click the Shape Track button to perform the shape tracking analysis.
7. To perform additional analysis in a different direction from the first frame of the analysis, toggle the Forward and Backward box and click Shape Track again.