US Patent 7656395 Methods and apparatuses for compound tracking systems

A method, apparatus, and system for tracking movement of a device are described. The method includes steps of implementing a first tracking subsystem for tracking positions of a device against a surface, determining whether to implement a second tracking subsystem for tracking positions of the device against the surface, capturing data corresponding to a location on the surface, and determining a position of the device against the surface based on the captured data. The position of the device can then be transmitted to a host computer and used in an application program. The first and second tracking subsystems may be a relative and an absolute tracking subsystem respectively.