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. Since you perform camera tracking first, you can use the camera data generated from the camera tracking analysis. For example, you can perform a camera tracking analysis on the complete scene, then use masks or mattes to perform multiple object tracking passes focusing on various moving objects in the scene. Each result can be converted to separate point clouds or axes, but all results conform to the FBX camera synced to the original camera tracking.
To create an 3D track analysis based on object properties:
Select: | To: |
---|---|
Free 3D Motion | Track an object moving independently from the camera. |
Orbit Around Cam | Track an object rotating around the camera, or far away from the camera. |
Auto Detect Motion | 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. |
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.
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.
Use the Filter settings to delete lower quality trackers and the Trackers settings manually add and link trackers.
To fine-tune the track analysis:
Trackers of lower quality may hinder the accuracy of the camera tracking.
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.
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.
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 a point cloud or axes.
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:
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.
Converting Object Tracking Results
When you are satisfied with the results of the 3D object tracking analysis, you can convert the selected reconstructed points to a point cloud object or actual axes in your scene. The point cloud object is useful because you can easily snap objects to the point cloud.
To create a point cloud object or axes from the 3D object tracking results:
Selected point are converted to a point cloud object with a parent axis. Double-click the newly created point cloud object to access its menu, where you can change display settings and enable snapping. See xxx.
Selected points are converted to axes with a parent axis. The axes synchronize to the results of your 3D camera tracking, and any further changes you make to the 3D track are reflected in these axes.
You can attach objects such as surfaces, 3D text, and 3D models to the new point cloud or axes to help position them in 3D space. See Using the Point Cloud Object.