Jan 17, 2012

Head Tracking in Detail

Head tracking is one thing that should consider when implementing the interactive VR applications. It is needed to calibrate the users' head position and orientation.

  • Optical Tracking

In optical tracking it uses camera and video stream as the input. Then the video frames are enhanced by image processing techniques and identify the certain feature of the image using vision technology. So that this feature identification can be determine the head position and orientation.  This can be divided into two parts.

  1.  image feature based tracking

 Shape, color and organization of the organs in the face are considered as feature parameters in feature based tracking. Just to mention few examples are  Elliptical head tracking systems, example based head tracking system, color based head tracking systems using intensity gradients and color histograms.

  1.  Marker based tracking

Two or more cameras are using for 6DOF tracking.  Marker based tracking can be divided into two parts. They are active maker based tracking and passive marker based tracking. Both are using simple vision algorithms to calibrate head position and orientation. Active marker based tracking are accurate and fast and passive marker based tracking is simple and inexpensive. 

  • Wii remote tracking

Comparing with optical marker based tracking, Wii mote tracking is more accurate. And marker based tracking has certain limitation.
  1. Light condition may affected for accurate tracking
  2. Markers may got invisible.
  3. LED markers may be good but it is also confused with light illumination problems.
  4. Environment should not contain colors that related to markers 
Using four IR lights wii mote tracking can be done but dur to inability of identify IR lights separately can not get the orientation correctly.

  •  Head Tracking with Consumer Products 

  1. FAAST
FAAST is middleware to facilitate integration of full-body control with games and VR applications.  The toolkit relies on upon Microsoft Kinect sensors. includes a custom VRPN server to stream the user’s skeleton over a network, allowing VR applications to read the skeletal joints as trackers using any VRPN client. Additionally, the toolkit can also emulate keyboard input triggered by body posture and specific gestures. This allows the user add custom body-based control mechanisms to existing off-the-shelf games that do not provide official support for depth sensors.

FAAST is free to use and distribute for research and noncommercial purposes (for commercial uses, please contact us). If you use FAAST to support your research project, we request that any publications resulting from the use of this software include a reference to the toolkit .

  1.  Wii system
Nintendo completely redefined the nature of the competition with the release of its Wii system.  Comparing with xBox360 Nintendo's price is cheaper.

  • Sources
  1. J. D. Mulder, J. Jansen, and A. V. Rhijn, “An affordable optical  head  tracking  system  for  desktop  VR  /  AR systems,” in Proc.  workshop on Virtual environments 2003, pp. 215-223.

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