2017

3 From the Object Motion box, make a selection about the object you are tracking in relation to the
camera.
To:Select:
Track an object moving independently from the camera.Free 3D Motion
Track an object rotating around the camera, or far away from the camera.Orbit Around Cam
Automatically detect the motion type of the object and track accordingly. For
small objects, Auto Detect may not be able to establish the proper motion.
In this case, select Free 3D Motion or Orbit Around Cam.
Auto Detect Motion
4 Set any needed constraints:
■ Use the Matte Media box to select whether to use the Action matte for object tracking. If you select
to track inside the matte, white areas of the matte are considered for calculating the solution, and
black areas are ignored (vice-versa for tracking outside the matte).
■ Use the GMask Option box to select whether to track inside or outside of an attached GMask node.
This option is only available if a GMask node is attached to Analyzer tree. If you used a GMask
constraint while camera tracking, the opposite option is automatically selected for object tracking.
The GMask Option box is unavailable on Smoke, unless a setup is loaded in Action with an existing
Action Gmask node.
The tracking analysis uses an intersection of the constraints, so you may choose to hide or disconnect
gmasks if you want to perform a separate object track for each one.
5 In the Object Tracking section, enable Forward and Backward to track the image sequence backward
after the forward tracking has completed. This option takes longer, but you may get better results.
6 Set the size of the automatic trackers in the size field.
664 | Chapter 15 Compositing in 3D Space with Action