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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. Its primary focus is head tracking with uses in virtual reality, simulation, video games, 3D modeling, computer aided design and general hands-free computing to improve computer accessibility. Tracking can be made sensitive enough that only small head movements are required so that the user's eyes never leave the screen. A camera is positioned to observe a rigid point model worn by the user, the points of which need to be isolated from background light by means of physical and software filtering. Motion is tracked with up to six degrees of freedom (6DOF), specifically; yaw, pitch, roll, left/right, up/down and forward/back. Windows compatible video devices like webcams are supported, as well as special support for the Nintendo Wii Remote camera and NaturalPoint cameras (TrackIR, SmartNav and OptiTrack). FreeTrack can output head tracking data to programs directly using its own open interface, as well as TrackIR, SimConnect and FSUIPC interfaces. Programs that support these interfaces are regarded as being FreeTrack-compatible. FreeTrack can also emulate mouse, keyboard, and joystick (via PPJoy) if a program does not support a direct interface. FreeTrack is coded in Delphi 7 and uses DirectShow and DirectX. Head tracking is achieved using implementations of DeMenthon's four point iterative pose estimation algorithm (POSIT) and Alter's three point geometric algorithm. ==Software== FreeTrack uses a camera to collect real-time information on the point model worn by the user. Specifically the image coordinates of the model points, which are either received directly from the camera or extracted from a video stream. These coordinates are used to generate an estimate of the real head pose, which can be transformed by the user in a number of ways to create a virtual pose. One of the most fundamental transformations involves amplifying rotation so that only small head movements are required. Finally, the virtual pose is sent to the user's choice of outputs. This is all done in the background, with tracking status displayed in the system tray. A 3D preview is available that shows the virtual head position and orientation for a given real head pose and can be viewed from multiple perspectives, including first-person. This greatly assists with testing and makes it easier to experiment with different settings. Each degree of freedom (axis) has a response curve that can be modified to change the way the virtual head moves for a given real head movement. This is commonly used to create a central deadzone region so that the user’s head can be more relaxed there. Keyboard, mouse and joystick buttons can be used to toggle tracking settings, including the virtual centre location (like adjusting the seat position in a car) and individually toggle axes and outputs. For NaturalPoint cameras, FreeTrack can provide advanced features and a level of customization that is not available with official software. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「FreeTrack」の詳細全文を読む スポンサード リンク
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