Tracking

Interaction » Tracking

The tracking module is responsible for connecting an external tracking system to VRED by communicating to one or more VRPN (Virtual Reality Peripheral Network) servers. VRPN is an open source standard library for accessing many different tracking systems with a unified approach.

Devices (tab)

The first and most important tab of the tracking module within VRED is dedicated to the tracking devices and their sensors. Each tracking device represents a complete tracking system consisting of a tracking space, a coordinate system and one or more sensors. This tab allows you to define VPRN devices. VRPN provides the connection support between the application and all kinds of devices using the appropriate class-of-service for each type of device sharing this link. These devices may be tracker, button devices, haptic devices, analog inputs, or sound.

Context Menu

Add device

Adds a VRPN device. Type in a resource in URI notation.

Remove device

Removes the selected VRPN device.

Reset device

Resets the selected device to its initial state.

Edit calibration

Edits the calibration matrix of the selected device. The calibration matrix is a measurement mapping of the real space to the virtual space. The following options appear:

• Clear Translations: Clears any translation (offset) in the matrix.
• Lock Rotation 90°: Lock the rotation angle in 90° steps.
• Matrix Transformation mode:

  Reset: Resets the matrix to its initial state.

  Z-Up to Y-Up: Retransforms the matrix so that Y-axis not represents the up-vector.

  Y-Up to Z-Up: Retransforms the matrix so that the Z-axis now represents the up-vector.

  Rotation: Sets the rotation of the projection for X, Y, and Z-axis.

Reset calibration

Resets the calibration data to standard values.

Calibrate

Calibrates the selected device.

Clear Config

Clears the complete configuration.

All presets are deleted.

Load Config

Loads configuration data from an .xml-file.

Save Config

Saves configuration data to an .xml-file.

You can add a tracking system using the context menu in the device list. After you enter the name (in the form trackername@computername) a connection to that VRPN server is established. To start or stop the complete tracking process is possible by clicking the checkbox Enable Tracking left of the device list. Use the last two columns in the device list to rotate the coordinate system (Z-Up) and enable or disable the complete device (On). You can also calibrate the coordinate system can also calibrate. A calibration needs one sensor that describes the new coordinate systems, both its new origin and its new orientation. Editing the calibration matrix directly is possible, but it is discouraged to use this method. When a device is created and selected, sensors can be added to the device. Unfortunately, VRPN does not tell which sensors are connected, therefore it is necessary to enter them manually in the sensor list. You can also name each sensor for accessing these using Python-scripts. The name has no other function. The following sensor types are supported using the context menu:

Add Body

Bodies probably are the most interesting sensor, as they are the only sensors that have a position and orientation in space. Thus they are also the only sensors that can be calibrated or connected to a node. Connecting a body to a node is an important task that updates a transform nodes matrix with the values coming from the corresponding sensor.

Add Button

Buttons are simple trigger buttons that have a unique identifier and target. You do not need to calibrate buttons.

Add Dial

This type of sensor can detect states on rotary dials such as a volume control on a stereo system.

Add Analog

Analogs are analog pointing devices, such as joysticks. Each movement axis must be mapped by adding an analog sensor.

Other functions available on context menu

Remove Sensor

Removes the currently selected sensor.

Reset Sensor

Resets the currently selected sensor.

Edit Calibration

Lets you change the values got from the calibration procedure by numerical input.

Reset Calibration

Resets calibration values for the selected sensor.

Calibrate

Receives position and orientation from the tracking system.

Servers (tab)

The second tab of the tracking module contains a list of VRPN servers that the cluster service controls. You can add new servers by using the context menu and entering their network address. All servers in this list can be started and stopped using the context menu. The cluster service must be running on the remote machine to be useable with this list. Right click in the window to see submenu:

Add server

Adds a tracking device.

Remove server

Removes the selected tracking server.

Start server

Starts the selected tracking server

Stop server

Stops the selected tracking server.

Refresh servers

Refreshes all tracking servers defined.

Navigation

Requires the availability of a flystick (ART).

Navigation Type

• None: No navigation type is selected.
• Scene Move: Moves the scene when moving the tracking body as long as you press the button.
• Point Fly: Flies forward/backward according to flystick orientation, or lets you rotate around flystick axis.
• Calibrated Cart: This is used in the special automotive Sitzkisten scenario.

Navigation Configuration

• Navigation Tracker: Select a navigation tracker device.
• Navigation Button: Select a navigation button device.
• Horizontal Analog: Select a sensor for the horizontal navigation tracker device. These sensors can be defined using the Devices tab.
• Vertical Analog: Select a sensor for the vertical analog navigation tracker device. These sensors can be defined using the Devices tab.

Cart Calibration

Calibration Tracker

Select the Calibration Tracker from the drop-down menu.

Offset Transform Node

Sets the offset transform node.

Use Cart Calibration

Check whether you want to use cart calibration or not.