If the image sequence you are tracking has multiple moving objects, you can perform object tracking to track these objects relative to the same camera. You can select the camera to which the object tracking results conform, or use the camera generated from previous camera tracking analysis. For example, you can perform a camera tracking analysis on the complete scene, then use mattes to perform multiple object tracking passes focusing on various moving objects in the scene. Each result can be converted to separate axes, but all results conform to the camera created by the original camera tracking.

To create an automatic 3D track based on object properties:

1. From the 3D Tracker option box, select Automatic, then click Object Tracking.

   
   

2. Click New Object Track.
3. If previous tracking data exists, a message appears indicating that the data will be discarded. After you confirm, the Track Media field and Conform To Camera box are automatically set to match the previous 3D track data. You can change these settings.
4. Select either to use a matte or matte invert, and specify the Matte media. If you are performing multiple object tracking passes, it is a good idea to use a matte to exclude the objects to be tracked next.

   White areas of the matte are considered for calculating the solution; black areas are ignored (or vice-versa for Matte Invert).

5. Enable Backward to track the image sequence backward after the forward tracking has completed. This option takes longer, but you may get better results.
6. From the Object Motion box, make a selection about the object you are tracking in relation to the camera.

   Select:	To:
   Free 3D Motion	Track an object moving independantly from the camera.
   Orbit Around Cam	Track an object rotating around the camera, or far away from the camera.
   Auto Detect	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.

7. From the Icons section, select tracker display options.

   
   

   Enable:	To display:
   Trackers	2D tracks. Use the colour pot to select the colour of the tracks.
   Points	3D points. Use the colour pot to select the colour of the points. The points option is also available in the Display section of the Setup menu (or with the hotkey Alt+D), so that you can enable the display of 3D points while working in other Action menus. 3D points are viewable in 3D in all Camera views in Action (Side, Front, Top, or Camera) to help you position objects in the reconstructed scene.

   You can also adjust the transparency of the trackers and points, and the size of the points in your image.

   Use the Grid box to display a grid so that you can position objects in the scene more accurately. The same Grid box is available in the Display section of the Setup menu.

8. Click Track.

   
   

   Most of the time, tracking occurs in the background, allowing you to continue working while tracking. In Batch, you can use connected input and matte clips as the media to be tracked. If this case, tracking becomes a foreground process.

   You can see a progress indicator beside the Track button. You can interrupt the analysis and resume it by clicking Track again. After tracking has completed and you press Confirm, the Track button changes to Calibrate, and you can see the 2D tracks and 3D points in your image.

9. Set the name and scale of the track in the Object Properties section.

   
   

   Name fieldDisplays the name to be given to the parent axis after you convert the analysis into axes. You can rename it to a better name to reflect which object you are tracking.

   Scale fieldDisplays the scale of the tracked object. After tracking has occurred, you can set the scale of the tracked object. Since you are tracking a specific object as part of an image, setting the relative scale of the object in relation to the image helps you to position objects in the reconstructed scene when you convert the 3D points into axes.

   NoteAfter creating axes, if the tracker is not reset, the axes stay in sync with the 3D tracker. Therefore, changing the scale value also has an impact on the created axes.
10. If you are satisfied with the results of the tracking analysis, proceed to Converting the 3D Auto Tracking Results. If you want to tweak your track results, see Fine-tuning the 3D Auto Track.