Data structure of digital map file

A terminal device for reading a cartographic file from a storage device in which cartographic files are stored as digital data generated for individual units formed by dividing a map into a plurality of areas, wherein

• each of the cartographic files stored in the storage device is provided with a file name uniquely corresponding to the map area represented by itself;
• said terminal device comprising:
• an input device responsive to an operation by a user for generating information specifying a map area;
• a data processing portion for specifying a record region where a necessary cartographic file is recorded on the basis of the information generated by said input device;
• and
• a read control portion for reading the cartographic file from the storage device on the basis of the record region specified by said data processing portion.

A terminal device for reading a cartographic file from a storage device in which cartographic files are stored as digital data generated for individual units formed by dividing a map into a plurality of areas, wherein:

• each of the unit contains a background which is divided into objects each capable of being drawn with one stroke, the plurality of objects being grouped so that ones having the same attribute are contained in the same group;
• and
• the cartographic file contains background records in which information about the objects is recorded for each group;
• said terminal device comprising:
• an input device responsive to an operation by a user for generating information specifying a map area;
• a data processing portion for specifying a record region where a necessary cartographic file is stored on the basis of the information generated by said input device;
• a read control portion for reading the cartographic file from the storage device on the basis of the record region specified by said data processing portion;
• and
• an output device;
• wherein said data processing portion causes said output device to display the background on the basis of the background records contained in the cartographic file read by said read control portion.

A recording medium in which cartographic files are recorded as digital data generated for individual units formed by dividing a map into a plurality of areas, the cartographic files having a predetermined data structure for reading by a computer device, said recording medium comprising:

• node records generated for respective nodes which form a road network in the unit in each cartographic file;
• and
• link records generated for respective links which form the road network in the unit in each said cartographic file;
• said node records each containing information about a non-neighboring node which represents an intersection on the road network, or coordinate information showing coordinates of a neighboring node which defines a connection of roads between a unit and a unit adjoining said unit;
• wherein said recording medium allows the computer device to:
• generating area information specifying a map area in response to an operation by a user;
• specify a record region where a required cartographic file is recorded on the basis of the generated area information;
• read the cartographic file on the basis of the specified record region;
• and
• while searching for a route by using the node records and the link records recorded in the read cartographic file, trace a connection from a road in one unit to a road in another neighboring unit on the basis of the coordinate information about the neighboring nodes of the one unit and the neighboring another unit.

A recording medium in which predetermined data is recorded for reading by a computer device, and in which cartographic files are recorded as digital data generated for individual units formed by dividing a map into a plurality of areas, having a structure, said recording medium comprising:

• the cartographic files as digital data generated for the individual units formed by dividing the map into a plurality of areas;
• and
• management information for managing record regions where said cartographic files are recorded, where said cartographic files are provided with names represented in a tree structure;
• wherein said recording medium allows the computer device to:
• when area information specifying a map area is entered from outside, specify the name of a necessary cartographic file on the basis of the input area information;
• and
• reading the cartographic file from the record region uniquely corresponding to the name of the specified cartographic file by referring to said management information.

A recording medium in which cartographic files are recorded as digital data generated for individual units formed by dividing a map into a plurality of areas, said cartographic files having a predetermined data structure for reading by a computer device, wherein:

• each of the unit containing backgrounds, each background being divided into objects each capable of being drawn with one stroke;
• wherein said recording medium comprises:
• information which show attributes of the backgrounds;
• and
• object records which contain information required to draw the objects;
• wherein said information showing the attributes of the backgrounds and said object records of the objects are successively recorded so that the plurality of objects are grouped according to their respective attributes;
• and
• wherein said recording medium allows said computer device to draw a map on the basis of said attribute information about the backgrounds and said object records contained in the cartographic file.

A terminal device for reading a cartographic file from a storage device in which cartographic files are stored as digital data generated for individual units formed by dividing a plurality of maps on different scales each into a plurality of areas, wherein:

• the plurality of cartographic files have a hierarchical structure based on the scales, each unit containing a road network represented by nodes and links, each cartographic file at least containing node records which are generated for respective nodes and contain coordinate information about nodes, and link records which are generated for respective links;
• and
• in each cartographic file, the node records are recorded in an ascending or descending order of the coordinate information about the nodes;
• said terminal device comprising:
• an input device for generating information specifying a map area;
• a data processing portion for specifying a record region where a necessary cartographic file is recorded on the basis of the information generated by said input device;
• and
• a read control portion for reading the cartographic file from the storage device on the basis of the record region specified by said data processing portion;
• wherein said data processing portion searches for a node in a unit at a higher level which corresponds to a node contained in a unit at a lower level on the basis of the coordinate information recorded in the cartographic file read by said read control portion.

A system in which a center station provides a cartographic file to a terminal device through a transmission path, said system comprising:

• said center station which comprises:
• a first storage device containing the cartographic file, the cartographic file representing a map of a predetermined area;
• a read control portion for reading, as cartographic data, part or all of the cartographic file from said first storage device;
• a packet assembler for assembling packets in a form appropriate for the transmission path by using the cartographic data read by said read control portion;
• and
• a transmitting portion for transmitting the packets assembled by said packet assembler to said terminal device through the transmission path;
• said terminal device which comprises:
• a receiving portion for receiving the packets transmitted by said transmitting portion through the transmission path;
• a data processing portion for disassembling the packets received by said receiving portion and restoring the cartographic data;
• and
• a second storage device having an internal storage medium for storing a cartographic file;
• wherein when a cartographic file related to the cartographic data restored this time is already stored in said second storage device, said data processing portion reads that cartographic file from said second storage device, and said data processing portion performs the process of adding the restored cartographic data to the second cartographic file thus read and stores the cartographic file in said second storage device.