Optical tracker system targets virtual reality

A FireWire-based system enables real-time, six-degrees-of-freedom motion tracking for virtual reality

Imagination Computer Services has developed a line of products using a reflective, IR LED strobed imaging system with FireWire-based camera modules.

To enable affordable, real-time, six-degrees-of-freedom (6-DOF) motion tracking for virtual reality (http://en.wikipedia.org/wiki/Virtual_reality), Imagination Computer Services (Vienna, Austria; www.iotracker.com) has developed a line of products using a reflective, IR LED strobed imaging system with FireWire-based camera module (watch the video below).

A typical iotracker system comprises four to eight Firefly MV 1394a camera modules from Point Grey Research (Richmond, BC, Canada; www.ptgrey.com), one synchronization unit, a PC workstation running iotracker software, and several rigid-body targets attached to various interaction devices.

The goal of the system is to calculate the exact pose (position and orientation) of a tool, object, or person within a predefined coordinate system. Optical motion trackers typically use multiple 2-D cameras to detect infrared-emitting or retro-reflective markers affixed to some interaction device. Based on the information received from multiple cameras, the system is able to calculate the location of every marker through geometric triangulation. When more than two markers are grouped together to form a rigid-body target, it becomes possible to determine the target's orientation, yielding a total of 6 degrees of freedom (6-DOF).


The iotracker cameras can be wall- or tripod-mounted. They are shutter-synchronized to a trigger-pulse signal sent out by the synchronization unit over a BNC coaxial cable. Every camera streams digital video to the tracking workstation via IEEE 1394a. The iotracker software running on the workstation computes the position and orientation of every rigid-body target in real time and transmits the resulting 6-DOF measurements to subscribed client machines over a TCP/IP Ethernet network.

Imagination Computer Services was found in 2005, when members of the Virtual Reality Research Group at Vienna University of Technology grew frustrated with the prohibitive prices and usability limitations of commercial motion-tracking technologies. The iotracker workflow is tailored to the needs of a virtual reality application developer. It includes a VRPN (Virtual Reality Peripheral Network) device server that enables developers to integrate the system with a large number of commercial and non-commercial third-party software packages.


-- Posted by Conard Holton, Vision Systems Design, www.vision-systems.com

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