3D Compositing with Action > Action: Analyzer > Camera Tracking >
Fine Tuning the Analysis

If the initial camera track analysis does not give desired results, you can use some or all of the Fine Tuning options to calibrate and refine your track analysis. These procedures are not necessarily required, but depending on your image and the initial tracking, may give better tracking results.

Performing Lens Correction

The Lens Correction settings in the Fine Tuning tab are the same settings that appear in the Analysis tab. You can apply lens correction before or after your initial analysis. If you make any changes after analysis, you'll need to calibrate or refine the track.

Setting the Orientation

Although it is not mandatory to define a ground plane in your image, it helps orient the reconstruction of the cameras.

To define the camera track ground plane:

1. In the Plane section of the Fine Tuning tab, enable Define.
   NoteIf you selected Pan and Tilt as the camera type (or if the Auto Detect switched to Pan and Tilt) the Plane Define button is not available. The rest of the settings in this group are still available, but only for orientation purposes.
2. Select a minimum of three points in the image that represent the plane of the X/Z axes, such as the ground, a table, or any flat surface.

   The selected points appear as red squares with white crosses.

   TipYou may want to disable the tracker temporarily and point display options (or raise the transparency level) to help you find and select the plane points.
3. Use the Position and Rotation controls to define the orientation of the ground plane.
4. Use the Scale field to specify the scale of the scene.
5. Disable Define.

Filtering and Adding Trackers

Use the Filter settings to delete lower quality trackers and the Trackers settings manually add and link trackers.

To fine-tune the track analysis:

1. Use the Quality slider to adjust the number of good trackers kept. The higher the quality setting, more low quality trackers are selected, such as trackers that drift off their initial reference point. Click Delete to delete the selected trackers.

   Trackers of lower quality may hinder the accuracy of the camera tracking.

   NoteAfter you have made a change that requires the 3D tracking analysis to be refined or calibrated, notice that the LED next to the Refine and Calibrate buttons turns yellow. This signifies that a Refine or Calibrate is required, but you do not have to perform it until you have completed your tracker selections.
2. Adjust the Short slider to select short duration trackers, that is, trackers that only track a feature for a few frames. Click Delete to delete the selected trackers, leaving the longer duration trackers intact.
3. You can manually select and delete trackers from the image that you feel are not tracking properly. Do one of the following:
   - To select an individual tracker, click the tracker, and then click Delete.
   - To select multiple trackers in the same area, Ctrl-drag a selection box over a series of trackers, and then click Delete.
   - To add another tracker to a multiple selection, Shift-click the tracker, and the click Delete.
   - With Delete mode selected in the Edit Mode box, select trackers in the image.
4. If you want to add a tracker manually, enable Add and click an area of the image to track from this area automatically.

   A tracker may or may not be added, depending on the ability of the track analysis algorithm to find an appropriate feature to track in this area.

5. If the analysis creates different trackers that refer to the same feature in the image, you can link these trackers. Press Shift and select two or more trackers from the image, and then click Link.

   For example, an element leaving the scene at frame 28 and returning at frame 50 may result in two different trackers attached to the same element in the image. In this case, select the trackers and click Link to teach the algorithm that these trackers are related to the same feature in the scene.

Refining or Calibrating the Track

Once you are satisfied with your fine tuning changes, you can refine or calibrate your Analyzer.

To refine or calibrate the 3D track:

1. Depending on the changes you have made, you can choose to refine or calibrate the 3D track. Do one or both of the following:
   - Click Refine.

   The track analysis uses the current results as a starting point, and refines from this point.

   Click Refine again to stop the process once an acceptable pixel error value is reached. The pixel error value is a representation of the distance of the 2D tracks from the computed 3D points.

   TipThe refine process is footage-dependant, so your acceptable pixel error value may change depending on what is tracking. Since the refine process continues until you stop it, as a general rule, if the pixel error value does not change for a length of time (for example, 30 seconds), you can stop the refine process. The lower the pixel error value, the more accurate the reconstructed track is.
   - Click Calibrate.
   NoteThe calibrate operation deletes all previous 3D points and starts over based on the new information. Depending on your footage, and how many trackers you added, deleted, or linked, multiple calibrations may yield different results.