Main Page → Trackables pane
The Trackables pane can be accessed under the View tab or by clicking the icon on the main toolbar.
The Trackable pane is used for creating and editing trackable models in Motive. In general, rigid body models are created for tracking rigid objects, and skeleton models are created for tracking human motions. This page goes over each option in the Trackables pane.
These trackable models, also called trackable assets, store marker placement information of the target object that will be tracked. Then these models are used to automatically apply a set of predefined labels to 3D points using the labeling algorithms. Once the 3D points are labeled, Motive can process the dataset to calculate the position and orientation of the corresponding rigid bodies or skeleton segments. Then, both rigid body and skeleton tracking data can be sent to other pipelines (e.g. animations and biomechanics) for extended applications.
The trackable models can be used to auto-label 3D points both in Live mode (real-time) and in the Edit mode (post-processing). If new skeletons or rigid bodies are created during post-processing, the Take will need to be auto-labeled again in order to apply the changes to the 3D data.
For creating rigid bodies, you need to select the rigid body option at the bottom of the Trackables pane and access the Create tab at the top. Here, you can create rigid body asset and track any markered-objects in the volume. In addition to standard rigid body assets, you can also create rigid body models for head-mounted displays (HMDs) and measurement probes as well.
Click Create to define a rigid body asset from the selected markers.
Other ways to create a rigid body. You can also define create the rigid body by doing the following actions while the markers are selected:
If the rigid bodies, or skeletons, are created in the Edit mode, the corresponding Take needs to be auto-labeled. Only then, the rigid body markers will be labeled using the rigid body asset and positions and orientations will be computed for each frame.
This feature can be used only with HMDs that have the OptiTrack Active HMD clips mounted.
For using OptiTrack system for VR applications, it is important that the pivot point of HMD rigid body gets placed at the appropriate location, which is at the root of the nose in between the eyes. When using the HMD clips, you can utilize the HMD creation tools in the Trackables pane to have Motive estimate this spot and place the pivot point accordingly. It utilizes known marker configurations on the clip to precisely place the pivot point set the desired orientation.
HMDs with passive markers can utilize the External Pivot Alignment tool to calibrate the pivot point.
Using the Trackables pane, you can also modify existing rigid body assets. For editing rigid bodies, select the rigid body option at the bottom of the Trackables pane and access the Edit tab at the top. This will bring up the options for editing a rigid body.
This feature is supported in Live Mode only.
Rigid body refinement tool improves the accuracy of rigid body calculation in Motive. When a rigid body asset is initially created, Motive references only a single frame for defining the rigid body definition. The rigid body refinement tool allows Motive to collect additional samples in the live mode for achieving more accurate tracking results. More specifically, this feature improves the calculation of expected marker locations of the rigid body as well as position and orientation of the rigid body itself.
The Probe Calibration feature under the rigid body edit options can be used to re-calibrate a pivot point of a measurement probe or a custom rigid body. This step is also completed as one of the calibration steps when first creating a measurement probe, but you can re-calibrate it under the Edit tab.
The Edit tab is used to apply translation or rotation to the pivot point of a selected rigid body. A pivot point of a rigid body represents both position (x,y,z) and orientation (pitch, roll, yaw) of the corresponding asset.
You can also use the Gizmo tools to quickly make modify the pivot point of a rigid body
The OptiTrack Clip Tool basically recalibrates HMDs with OptiTrack HMD Clips to position its pivot point at an appropriate location. The steps are basically the same as when first creating the HMD rigid body.
This tool can be can be used for HMD with passive markers.
For using OptiTrack system for VR applications, it is important that the pivot point of HMD rigid body gets placed at the appropriate location, which is at the root of the nose in between the eyes. External Pivot Alignment tool utilizes both the OptiTrack mocap system and the Oculus Tracker for precisely calculating the location of the pivot point of an Oculus HMD. When using this feature, both systems must be tracking the HMD simultaneously.
This feature is useful when tracking a spherical object (e.g. ball). It will assume that all of the markers on the selected rigid body are placed on a surface of a spherical object, and the pivot point will be calculated and re-positioned accordingly. Simply select a rigid body in Motive, open the Trackables pane to edit rigid body definitions, and then click Apply to place the pivot point at the center of the spherical object.
To create skeletons in Motive, you need to select the skeleton option at the bottom of the Trackables pane and access the Create tab at the top. Here, you select which skeleton markerset to use, choose the calibration post, and create the skeleton model.
In Edit Mode
If you are creating a skeleton in the post-processing of captured data, you will have to auto-label the Take to see the skeleton modeled and tracked in Motive.
Virtual Reality Markersets
Skeleton markersets for VR applications have slightly different setup steps. Please refer to the corresponding pages for more infromation:
Existing skeleton assets can be recalibrated using the existing skeleton information. Basically, the recalibration recreates the selected skeleton using the same skeleton markerset. This feature recalibrates the skeleton asset and refreshes expected marker locations on the assets.
To recalibrate skeletons, select all of the associated skeleton markers from the perspective view along with the corresponding skeleton model. Open the Trackables pane, and open the Edit tab while Skeleton option is selected at the bottom. Make sure the selected skeleton is in a calibration pose, and click Recalibrate. You can also recalibrate from the context menu in the Assets pane or in the 3D Viewport.
Skeleton recalibration do not work with skeleton templates with added markers.