To operate properly, Freetrack needs markers in order to represent the position of your head in space.
Depending on the selected mode , Freetrack will need 1 (Single Point mode), 3 (3 Points Clip mode, 3 Points Cap) or 4 (4 Points Cap mode) markers.
These markers, located on a support (usually a cap for Single Point and 4 Points Cap modes, or a clip fastened on your headset for 3 Points Clip mode) are in fact Light Emitting Diodes (LEDs). Detected by your webcam, they allow the Freetrack software to convert your head movements in data flow which can be used by your game/simulator.
In order to use Freetrack day or night, choice of IR (Infrared) LEDs is advised. Thus, your webcam (equiped with an infrared filter) will only detect the markers and will not be affected by other light sources.
The vast majority of webcams are appropriate for Freetrack use.
The main advantage of this system, is his low cost (less than about ten euros), assuming you already own a webcam. In the other case, you'll have to count a webcam's price in the Grand total.
As an infra-red filter, a good tip is to use two or three dark photograph negatives (or better, not exposed) superimposed and installed in front of the cam lens.
Caution : There is no need for an "Infrared webcam” !!! The plain usual webcam works fine !
Most answers to questions about Freetrack use, system building, LED choice, ..., are included in the complete handbook, written by Babasior, and available here . Moreover, you can obtain some help in the Forum.