While simulating flight on personal computers, head tracking represents an obvious advantage when compared to other available methods of controlling the view: using the keyboard or the POV hat on the joystick. This is achieved in an almost natural way: by moving one's head the user controls rotation, translation and the zoom of the view, while the user's eyes must remain pointed at the display screen, which imposes certain limitations. Working principle of head tracking systems boils down to analyzing the image recorded by the sensor pointed at the user's head and sending the coordinates to the software that needs such coordinates. Actualization differs with different systems:
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Some systems use an IR point model attached to the head of the user, while the camera is supplied with the visible light filter, which provides for reliable head tracking at home with the CPU load necessary for head tracking kept at relatively low levels. Perhaps the fact that the system Schel- 3UM, used on some Russian fighters such as the MiG- 29 and the Su- 27, which is based on a similar principle may be found interesting, the difference being that passive diodes are attached to the pilot's helmet, while rotating IR lamps situated below the HUD emit the IR radiation. Ambiental light filtering is performed on the basis of the IR pulse frequency dictated by the speed of the rotation of the lamps;
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Where IR cameras equipped with emitting IR diodes are used, tracking points on the point model can be covered with IR reflecting material, thus eliminating the need to fit IR emitting diodes on the point model itself. This solution can be considered convenient from the standpoint of saving energy, since only the camera will need electric current, but on the other hand, and as a consequence of lower intensity of reflected radiation that reaches the cam, problems with filtering out the ambiental radiation will increase;
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In some instances, the image of the user's face is analyzed and no point model is used. CPU load required for head tracking is the highest in such cases;
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RUCAP head tracking system, which will be discussed in more detail on a separate page, has a different working principle. Reportedly, emission of ultra- sound is performed, which probably eliminates problems having to do with filtering out the ambiental radiation for the most part.
Aside from the use it found in simulating flight, head tracking is also used with car racing games, tactical simulations and first person shooters, but it can also be used as a substitute for usual control devices, such as a mouse or a trackball, by physically challenged people. Freetrack represents, perhaps, the most widely known free head tracking software, for successful use of which the user will need, aside from an off the shelf webcam, a point model which will be worn on the head and the position of which the camera will record. The reason for existence of this website is, among other things, offering
built point models for purchase to those who don't wish to bother themselves with building their own models.