TrackIR is an optical motion tracking device that used an infrared (IR) camera to track head motion manufactured by NaturalPoint. The user wears a hat or other rigid structure on the head with dots that reflect infrared light. These are used as reference points to generate motion data for the software. With the correct configuration the TrackIR can give fully six degrees of freedom and smooth, precise head tracking.
Image credit: By ShijarnocDreams (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
TrackIR started life not at a video game motion tracker, but as a device designed for accessibility. Disabled users could move a pointer with head movements if they lacked the mobility to use a mouse and keyboard.
It soon became apparent that the TrackIR had potential as a video game controller as well, specifically games that needed to simulate independent head movement.
In most 3D video games your viewpoint and the forward direction of the virtual body are locked together. In other words, you have to turn the entire body to change your field of vision. Something that’s been humorously referred to as a “bat-turn”, referring to actors that have played the DC character Batman. Their costumes often have stiff necks, preventing them from simply turning their heads to look at something.
This is fine in first-person shooters where the player isn’t really aware of their in-game body, but in games that simulate sitting in a cockpit things are a little different. In such simulators it’s necessary to independently steer the vehicle and look around within the cockpit.
Traditionally this function has been relegated to the “hat” switch of computer flight sticks, but this adds to the already complex control schemes of flight simulators. With head tracking the player can steer the craft with the flight stick and turn their in-game field of view by turning their own heads.
TrackIR has been available for purchase since 2001, so clearly it predates the modern virtual reality revolution. There is no head-mounted display, just the computer monitor. As such, most implementations of TrackIR do not use 1-to-1 motion tracking, but exaggerate the motions of the user’s head. Otherwise, if the user looked to the side for example, they wouldn’t see the screen.
The TrackIR has had many iterations since its debut and the proprietary TrackIR software standard still remains a major force in simulation software to this day. The TrackIR is certainly a pioneer of a technology which is integral to many modern virtual reality systems. The Playstation VR, for example, combines camera tracking with other internal inertial sensors to enable head-tracking.
TrackIR remains an industry leader in consumer head tracking, but it remains to be seen if it can keep this position in the face of virtual reality devices.