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Auto 3D Tracking

Auto 3D Tracking

Setting Camera Properties for Automatic 3D Camera Tracking

 

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

Automatic Camera Tracking

You can perform automatic 3D tracking based on the camera properties of the device used to acquire the image sequence you want to track. You can specify these properties, or let the 3D tracker automatically detect the best solutions for the analysis. Even if you want to perform object tracking on specific moving areas of the scene, you should start with an analysis using camera tracking to create a properly tracked camera.

To create an automatic 3D camera track:

1. From the 3D Tracker option box, select Automatic, then select Camera Tracking to display the Camera Tracking menu.
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. Decide if you need to use a matte in the analysis. 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.

   Select:	To:
   Matte On	Use a matte to delimit the tracking results. White areas of the matte are considered for calculating the solution, and black areas are ignored.
   Matte Invert	Use an inverted matte to delimit the tracking results. Black areas of the matte are considered for calculating the solution, and white areas are ignored.
   Matte Off	Not use a matte.

4. If you are using a matte, specify which matte in the Matte Media field.
   NoteUse a matte made from real frames. Keyer or Gmask outputs do not work as a matte for 3D tracking. Alternatively, in Batch, you can use connected input and matte clips as the media to be tracked. In this case, tracking becomes a foreground process.
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. Set Camera and Film Back options. See Setting Camera Properties for Automatic 3D Camera Tracking.
7. If needed, adjust the scale of the trackers in the Scale field.

   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.

8. 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 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.

9. Click Track. You can see a progress indicator beside the Track button. You can interrupt the analysis and resume it by clicking Track again.

   
   

   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. In this case, tracking becomes a foreground process.

   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.

   
   

   Image courtesy of Behavior Communications Inc.

   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.

   NoteDo not manually modify the Camera_3dt_sync parameters before finalizing your auto tracking results by converting points to axes and resetting the tracker. These modifications will be lost, as Camera_3dt_sync is linked to the 3D tracker. If you reset the 3D tracker settings, the synchronized camera becomes a regular Action camera that you can modify.
10. 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.