FreeTrack is a general-purpose optical motion tracking application for Microsoft Windows, released under the GNU General Public License, that can be used with common inexpensive cameras.

Specifically the image coordinates of the model points, which are either received directly from the camera or extracted from a video stream.

The Wii utilizes a low-resolution 128×96 sensor, which is found by some to produce jittery tracking and may require smoothing to improve stability at the cost of decreased responsiveness.

To put this into perspective, a human’s reaction time to visual stimulus (finger reflex) is typically around 200 ms; 30 ms can be regarded as a competitive ping in online reflex-based games, and an LCD monitor refresh rate is typically 17 ms. Higher responsiveness gives a greater feeling of control, but since virtual head motion is amplified, it can also cause it to move unrealistically fast.

FreeTrack requires the tracking points to be isolated from all other light; this is best done using infrared LEDs and a visible-light blocking filter in front of the camera.

All video devices like webcams have a built-in infrared-blocking filter, which can be removed to improve sensitivity to infrared light, allowing better point isolation and the possibility of retroreflective tracking.

Common LEDs, like those found in remote controls, have a narrow, highly focused beam which is not suitable for optical motion tracking.

Alternatively, wide angle LEDs can be purchased from specialist electronics retailers, like the infrared Siemens/Osram SFH485P, with a half-angle of 40 degrees.

This configuration doesn’t require wires or batteries connected to the user but is more susceptible to interference by background light.

FreeTrack has a simple interface that can be freely used by third party programs such as Eyeware Beam to access 6DOF tracking data, both real raw measurements and virtual.

[17] FreeTrack is compatible with the unencrypted version of NaturalPoint's head tracking TrackIR interface that has widespread support in simulation games.

[18] The developers of the first game affected, DCS: Black Shark,[19] tried to release their own head tracking interface but soon after canceled it at NaturalPoint's request.

[21] TIRViews.dll is a dynamic-link library file distributed with TrackIR software that provides tailored support for a small number of mostly older games, using special interfaces or memory hacks to facilitate view control.