A vehicle navigation system is known, in which a current position is calculated by utilizing a GPS (Global Positioning System) positioning function, a gyroscope, a vehicle speed sensor, and the like, and a local vehicle position is synthesized with map information on roads and buildings around the vehicle position to be displayed on a display.
Moreover, in accordance with the improvement in performance of portable terminal devices such as a cell phone and a PDA (Personal Digital Assistant), a pedestrian navigation system that has the GPS positioning function is realized even in these portable terminal devices.
An attempt has been made to improve convenience for passengers by connecting the portable terminal device having the pedestrian navigation function and the in-vehicle device having the vehicle navigation system. For example, Patent document 1 discloses a technology in which navigation to a destination is continued even outside a vehicle by transmitting navigation information from the in-vehicle device to the portable terminal device when a passenger leaves the vehicle.
Patent document 1: Japanese Laid-open Patent Publication No. 2002-181555