New features including the following were added to Vicon Tracker 3.

Filtering and smoothing

• Location: Resources pane > System tab > Local Vicon System > Properties pane > Object Tracking section.

  

Vicon Tracker 3.0 offers new filtering options to detect static objects and minimize jitter caused by marker occlusion.

In the Properties pane for Local Vicon System, the new Object Tracking section contains the System-wide Object Filter dropdown list.

To apply a filter to all objects, choose one of the options:

• None: No filtering of any objects, unless object-specific filtering is applied: see Choose different smoothing options for each object.
• Motion Model: Enables Tracker to detect static objects. When selected, Tracker outputs a constant position and orientation for an object from the time it is detected as not moving to the time it resumes motion. Use this option to clamp the position of an unmoving object to its previous known position.
• Bias Tracking: Applies a smoothing filter that tracks systematic errors in the camera measurements to minimize motion jitter when markers become occluded in the camera views.

Choose different smoothing options for each object

• Location: Resources pane > Objects tab > Filter Mode Preset section

Vicon Tracker 3.0 enables you to apply a One Euro low-pass smoothing filter to a selected object. Where you have multiple objects, you can apply different filtration settings to each object, enabling you to tailor the amount of filtration to the motion of the specific object.

To assist you in setting appropriate filtration for your objects, Tracker 3.0 provides the following commonly used filter mode presets:

• None: Apply no object-specific filtering to the selected object.
• HMD: Apply settings normally appropriate for head-mounted devices.
• InteractionDevice: Apply settings normally appropriate for ViconApex devices.
• General: Use as a general-purpose filtration type.

If none of the supplied filter mode presets is suitable for your application, you can also create and save your own custom filter mode presets, so that you can quickly and accurately apply them to other objects, as required.

To apply filtering to a selected object:

1. In the Objects tree at the top of the Objects tab, ensure that the object to which you want to apply the filter is selected.

2. Depending on whether you want to use an existing filtration type or create your own, do one of the following:

   • If you want to use one of the existing filter types, in the Filter Mode Preset section, select the required filter from the dropdown list and save the object as described in step 5.
   • If the required filtration type does not exist, in the Filter Mode Preset section, click Manage Presets and in the Filter Presets dialog box, enter a name in the Create New Preset box and then click Add .

3. In the Filter Presets section, ensure the new preset is selected, then in the Smoothing section, change the Translation and Rotation properties as required:

   1. With Translation Beta set to zero, change the value of Translation Min Cut-Off to eliminate jitter during very slow movements.

      Note that decreasing the value of Translation Min Cut-Off reduces jitter but increases lag.

   2. When you have finished adjusting the Translation Min Cut-Off value, increase the value of Translation Beta by very small increments to eliminate lag during faster movement.

      Note that 0 = filtering on all translation motion; 1 = filtering on very slow translation motion only.

   3. Follow the same procedure for adjusting the Rotation Min Cut-Off and Rotation Beta.

      For detailed information on the One Euro filter and how to adjust these settings, visit www.lifl.fr/~casiez/1euro/.

   4. When you have finished adjusting the properties, click Close.

4. On the Objects tab, make sure that in the Filter Mode Preset section, the required filter is displayed for the selected object.

   Tip: To apply a filter to an Apex device, select the device and in the General section of the Properties pane, from the Filtering Type list, select the required filtering type.

5. Save the object by right-clicking it the Objects list and selecting Save Object from the context menu.

Tracker saves the contents of the object in a .vsk file in the Objects folder.

Jitter reduction

• Location: Resources pane > System tab > Local Vicon System > Properties pane > System section > Low Jitter option.

  

To enable you to minimize jitter in marker positions while tracking objects, a new Low Jitter option is now available in System properties.

This option sets the Grayscale Mode for all cameras to Only (this is necessary to enable jitter reduction to work), and applies Tracker's jitter reduction algorithms to the current data. This reduces noise in the data by using advanced centroid fitting and other jitter reduction measures.

Improved processing

Vicon Tracker 3.0 has been re-engineered to significantly reduce processing latency and improve processing frame rate, even with high numbers of tracking objects and cameras, by making full use of modern multiple-core CPUs.

Improvements in processing rate mean that end-to-end latency may also be reduced by increasing the Vicon camera frame rate.

Access Tracker data from Simulink

See Accessing Vicon Tracker data from Simulink.

Other enhancements in Vicon Tracker 3.0

Further enhancements and updates including the following have been made in Tracker 3.

Calibration error displayed in millimeters

• Location: Resources pane > Calibration tab > Camera Calibration Feedback section > World Error column

  

In Tracker 3.0, the World Error column in the Camera Calibration Feedback section displays the calibration error in millimeters, giving you a sense of how much the errors in the camera contribute to the reconstruction of object pose error.

World error is calculated per camera from the Image Error in pixels and the distance of the camera to the center of the volume. Cameras further away display a higher World Error than cameras closer to the center of the volume with the same image error.

Easier setup of Apex devices

• Location: Resources pane > System tab> Devices node > Apex device node > Properties pane > General section

  

In the Properties pane for the selected device, the General section enables you to select from the following orientation options for the device coordinate system:

To facilitate the setting up of Apex devices within a virtual environment, Vicon Tracker incorporates options for the device axes.

• Y-Back Z-Up
• Y-Forward Z-Up
• X-Back Z-Up
• X-Forward Z-Up

This property is saved in the .system file.

The General section also contains the new Filtering Type field, where you can specify the filtering type for the selected Apex device. For more information on filtering types, see Choose different smoothing options for each object.

New hotkey/Tracker shortcut

A new hotkey (CTRL+E) creates a named object from selected markers.

This provides the same functionality as pressing the Create button in the Create Object section of the Objects tab.

Auto-naming of new objects

• Location: Resources pane > Objects tab > Create Object section

When you enter a name in the Create Object text box and click Create, the name is automatically incremented by 1, so that, to create another object with the default name of ObjectName_n, you can just select the required markers and click Create.

Additional VRPN output

• Location: Resources pane > System tab > Local Vicon System > Properties pane (to see all options, click Show Advanced) > VRPN Stream section

  

If you are rendering the same object to different display types (for example, to both a large screen and an immersive environment such as a head-mounted display), to obtain smooth visualization on both display types, you are likely to need to apply different amounts of filtration for each.

To enable you to do this, Tracker 3.0 provides a second set of VRPN Trackers, which are output with the existing ones. For easy identification, the names of this second set of VRPN Trackers are suffixed with _2.

The second set of VRPN Trackers includes customizable One Euro filtering. (For information on adjusting the filtering parameters, see Choose different smoothing options for each object.)

Easier upgrading

To make data migration easier between Tracker upgrades, you are given the option of migrating and updating shared user data stored in the old location (ProgramData\Vicon\Tracker) into the new location (C:\Users\Public\Documents\Vicon\Tracker3.x).

Improved analysis and troubleshooting for captured data

• Location: Resources pane > Recording tab

For each trial recorded, at least three files are saved: .x2d, .system, and .xcp files. With Vicon Tracker 3.0, an .x2d file containing the latest calibration data, of the format LatestCalibration yyyymmddnnnnnn.x2d, is also saved in the same location as the .x2d containing the recorded trial data.

The file that contains the calibration data can be useful for data analysis and troubleshooting. When you have captured a trial, you can find the calibration .x2d in the same location as the .x2d of the recorded trial.

New Track mode minimizes output latency

• Location: Resources pane > Objects tab> Object Tracking Mode section> Track mode button.

  

To minimize output latency, the new Track mode prevents the display of unlabeled markers in the 3D Perspective view. Because viewing unlabeled reconstructions requires additional processing, for lowest output latency, when you have finished creating objects, click the Track button to change to Track mode.

To turn off the display of unlabeled reconstructions:

• In the Resources pane, click the Objects tab and ensure that in the Object Tracking Mode section at the bottom of the tab, Track mode is selected.

  When Track mode is selected, the Track button is green. This mode switches off the display of unlabeled reconstructions in 3D Perspective view.

Set Camera view background to Threshold value

• Location: Options dialog box > General View Options section> Threshold option

To help you to determine the most effective threshold setting for grayscale blobs, you can set the background color of the Camera view to the value of the Threshold control in the Centroid Fitting section of the Properties pane. To do this:

1. Open the Options dialog box (F7), and in the General View Options, select Threshold.
2. On the System tab, select the camera and ensure that the view pane is displaying a Camera view.
3. For each camera, in the Properties pane:
   1. In the Settings section, ensure Grayscale Mode is set to All.
   2. In the Centroid Fitting section, adjust the camera's Threshold settings to obtain the clearest possible view of the blobs, with minimal flickering in the Camera view.

Automatic selection of cameras and view for masking and calibration

• Location: Resources pane > Calibrate tab > Create Camera Masks and Calibrate Cameras sections > Start button

A new time-saving feature of Tracker 3.0 improves the process of masking and calibration.

When you begin masking or calibration by clicking the Start button in the Create Camera Masks or Calibrate Cameras sections, the cameras are automatically selected and the view pane displays Camera views of all the selected cameras.

Change in Shared data locations

In Vicon Tracker 3, data is saved in the following folders:

• Shared files are saved in the appropriate sub-folder in: C:\Users\Public\Documents\Vicon\Tracker3.x\
• Private files are saved in the appropriate sub-folder in: C:\Users\UserName\AppData\Roaming\Vicon\Tracker3.x\

Change in default Minimum Cameras to Start Trajectory

• Location: Resources pane > System tab> Local Vicon System node > Properties pane > Reconstruction section

The Local Vicon System property Minimum Cameras to Start Trajectory specifies the number of cameras that must see the same marker to create a new reconstruction and potentially form a new trajectory.

In Tracker 3.0, the default value for this property is 3 (ie three cameras), so if you are using a two-camera system, ensure you change the value to two before starting to work with Tracker.