Abstract: A difference map distribution server wirelessly distributes update information contained in map data to a navigation apparatus that stores map data representing a road network using multiple links and nodes. Specifically, a difference information database stores difference data items to be categorized into multiple types of update information that enable update information about the same link or node occurred during the same period to be categorized into different types. A difference data extraction portion extracts a difference data item categorized into a type of update information to be distributed to a targeted navigation apparatus from the difference data items categorized into the multiple types of update information stored in the difference information database. A distribution controller wirelessly distributes the difference data item categorized into the extracted type of update information to the navigation apparatus via a network interface.

Abstract: A map difference data delivery apparatus generates map difference data, upon receiving a map update instruction for updating map elements in a map database. To generate the map difference data, the apparatus divides the map elements into multiple groups based on a user preference, such as travel frequency, road attributes, road shape, or road type. The generated map difference data thus includes the map elements exclusively accommodating and matching with the user preference.

Abstract: A guiding spot display apparatus displays a number of guiding spots for providing various guiding information on a road map. The apparatus includes a storage medium for storing a plurality of guiding spot data each being assigned a plurality of priorities and corresponding to one of a plurality of guiding classifications, a display selecting device for generating a display signal indicative of the classification of the guiding spots to be displayed, a control unit responsive to the selection signal to successively input from the storage medium the corresponding guiding spot data starting from the one having the highest priority and generate a display signal for displaying the data, and a display responsive to the display signal to display the selected guiding spots on the road map. Thus, the degree of the freedom in the display of guiding spots is improved and the apparatus is well suited for use in a wide range of guiding information application.