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Preparing to Track

Action: 3D Camera Tracking

Setting Camera Properties for 3D Auto Tracking

 

3D Compositing with Action > Action: 3D Camera Tracking > 

Auto 3D Tracking

The first step in 3D auto tracking is to perform your initial tracking. Depending on the result, you can also fine-tune the track.

To create a 3D auto track:

1. From the 3D Tracker option box, select Auto.
2. In the Track Media field, specify the media number of the front clip you want to track. A value of 0 indicates that the Back clip is tracked.

   
   

3. Enable Use Matte and specify the Matte media if you want to use a matte to delimit the tracking results. For example, in an image sequence of a busy street, you can create a matte of moving elements (such as cars and people) to isolate this area from the analysis.

   White areas of the matte are considered for calculating the solution; black areas are ignored (unless you selected Matte Invert from the Matte Clip box).

   NoteUse a matte made from real frames. Keyer or Gmask outputs do not work as a matte for 3D tracking.
4. If needed, set Camera and Film Back options. See Setting Camera Properties for 3D Auto Tracking.
5. If needed, select Analysis options.

   Enable:	To:
   Zoom	Calculate the zoom value of the reconstructed camera for each frame (assuming the camera that shot the tracked clip has a variable zoom value). By default, Zoom is disabled (that is, the track analyses with a fixed zoom).
   Backward	Track the image sequence backward after the forward tracking has completed. This option takes longer, but you may get better results.

6. If needed, adjust the scale of the trackers.

   Smaller trackers can speed up the calculation, while larger trackers make the analysis more robust with regard to image noise and variations. A general rule is to increase the scale of the trackers when tracking high-resolution footage (2K or larger) that contains more noise or less sharpness.

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 hot key Alt+D), so that you can enable the display of 3D points while you are 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. Tracking occurs in the background, allowing you to continue working while tracking.

   
   

   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 (the blue squares in the following example) and 3D points (green crosses) in your image, if you chose to display them.

   A camera called Camera_3dt_sync is also generated when an analysis is performed. This camera synchronizes to the results of your auto 3D tracking, and any further changes you make to the 3D track are reflected in this camera.

   NoteIf you reset the 3D tracker settings, the synchronized camera becomes a regular Action camera.

   
   

   Image courtesy of Behavior Communications Inc.

9. If you are satisfied with the results of the tracking analysis, proceed to Defining the Auto Track Ground Plane and Converting the 3D Auto Tracking Results. If you want to tweak your track results, see Fine-tuning the 3D Auto Track.