Abstract: In a map database apparatus in which a road is expressed by using a plurality of sets of data related to links each of which links has nodes at a front end and at a rear end, data related to a plurality of links provided separately for maps at different scales are respectively stored as roadmap data from a highest order level at a smallest scale through a lowest order level at a largest scale, a map area at a high order level is divided into a plurality of M small areas, each of sets of detail information corresponding to the M small areas is stored as a set of roadmap data of a map area at a low order level, and M sets of roadmap data are stored at the low order level: correspondence information between nodes at different levels when the low order level is viewed from the high order level is provided as level correspondence data that express corresponding relationships between roadmap data at the high order level at the small scale and roadmap data at the low order level at the large scale.

Abstract: A map display apparatus according to the present invention has a control circuit which divides a display screen of a display device into a plurality of regions, and processes a bird's-eye view data for each region and convert them into map image data. The control circuit then prepares vehicle information image data for displaying marks indicating current position and destination of the vehicle. In this step, mark data are prepared so that the mark is displayed at a display position corresponding to the destination when the destination is within a display range, and so that the mark is displayed at a display position that lies in the direction of the destination and is closest to the destination when the destination is not within the display range. Upon completion of preparation of the map image data and vehicle information image data, the control circuit displays these data on the display device, and then detects the current vehicle position again.

Abstract: A route search apparatus according to the present invention comprises: a storage device that stores link positional information of individual links and link connection information between the links, a minimum unit of road on a map being referred to as a link; a departure point specification device that specifies a point of departure on the map; a destination specification device that specifies a destination on the map; and a control device that selects a start point link that is to constitute a start point of a route search based upon the point of departure specified by the departure point specification device and the link positional information, selects an end point link that is to constitute an end point of the route search based upon the destination specified by the destination specification device and the link positional information, and performs a route search between the start point link and the end point link based upon the link connection information.

Abstract: A navigation system for vehicles comprises a read device that reads planar map data from a recording medium which stores in memory planimetric map data of a road map, a current position detection device that detects the current position of the vehicle, a storage circuit that stores in memory function tables for converting positional coordinates of nodes included in a road map area around the detected current position to positional coordinates of nodes on a bird's-eye-view map obtained by looking down upon the road map in a specific direction, at a specific look-down angle and a specific aspect angle from a viewpoint set above the vicinity of the detected current position and a bird's-eye-view map display data preparation circuit that reads out data related to coordinate positions of nodes on the bird's-eye-view map by operating the conversion table with the coordinate positions of nodes on the road map and prepares bird's-eye-view map display data for displaying the bird's-eye-view map on the monitor based up

Abstract: A navigation system according to the present invention comprises a database apparatus provided with map display data constituted of data representing road positions and physical forms provided in separate sets to correspond to different scales and route search data constituted of data representing connection states of one road connecting with another road provided in separate sets to correspond to different scales; and a control apparatus that, when displaying recommended route data obtained by performing a search using the route search data at a specific first scale superimposed upon a roadmap that is displayed on a monitor based upon map display data at a second scale that is larger than the first scale, reads out physical form data of the recommended route data obtained by performing the search using the route search data at the first scale based upon the map display data at the second scale and displays the physical form data superimposed upon the roadmap on the monitor.

Abstract: A microprocessor 24 detects turn start and turn finish of a vehicle on the basis of outputs of various sensors 11, 12 and 13, and during this operation, the microprocessor 24 successively sets a current position to a middle point of a next link every time a predetermined condition is satisfied. While the current position is shifted from the middle point of a link to the middle point of a next link, the vehicle travel azimuth output from the sensor is corrected to approach to the azimuth of the link by an amount corresponding to the difference between the link azimuth of the just-previous middle point and the vehicle travel azimuth, and the current position is displayed on the basis of the corrected travel azimuth and the travel distance. Information on each link is obtained form a road map which is stored in a CD-ROM 15 and in which roads are expressed by an assembly of links.

Abstract: A road on a map is expressed as link string data constituted with a plurality of links which represent minimum units of the road and nodes on a start point and an end point of the plurality of links. A map database apparatus is provided with a first storage device which stores in memory node information constituted with identifying information for identifying a plurality of links and position information of a node shared by adjacent links as map display data, and a second storage device which stores in memory home node information on an identical node, which is belonging to one link string data, with position information identical to that of a node of another link string data and adjacent node information which represents a node adjacent to the identical node in a link of another link string data to be connected to the identical node as route search information.

Abstract: The present invention is applied to a map database apparatus, where: a road is represented as a link string in which a plurality of links, each of which has nodes at both ends thereof, are connected; and a plurality of link string data, each of which includes node information relating to the node and is respectively provided for each of levels which correspond to different scale maps with regard to an identical link string, are stored. And a link of a lower level which has a larger scale, the link being common to a link of a upper level which has a smaller scale, has a link identifying data which is common to a link identifying data of the common link of the upper level.

Abstract: A navigation apparatus for displaying most appropriately information such as character strings, routes, etc., when a map is displayed by bird's-eye view display. The navigation apparatus includes a portion for calculating the present position on the basis of information from sensors, a portion for executing perspective conversion operation for displaying a map by bird's-eye view display, a portion for disposing the present position or the present position and a position representing a destination at the most suitable positions, a portion for controlling so that overlap of character strings can be eliminated, a portion for controlling the same character strings, a portion for displaying most appropriately a background such as lines and planes, a portion for controlling marks to be displayed, and a portion for executing graphic plotting by using the resulting map data.

Abstract: A current position calculation system is provided for adequately correcting a distance factor which is used for obtaining a travelled distance by utilizing various information at the time when a vehicle turns left or right. According to an output from a headed direction detecting device, an output from a travelled distance calculating device and road data of a road map, at the time when the vehicle turns left or right from a first road to a second road, there is obtained a distance error amount d which is an error in an output from the travelled distance calculating device with respect to an actual value it should be. The distance error amount d is corrected so as to be reduced.

Abstract: A map display apparatus according to the present invention has a display device capable of displaying a road map in different map forms in a base screen region and a window screen region. A control circuit determines whether the window screen is provided or not on the basis of input information entered through an input device, and determines which one of a planimetric map and a bird's-eye view is displayed in the base screen and the window screen. Either of the planimetric map and the bird's-eye view are displayed using road map data as a common map data base stored in a map storage memory, which eventually reduces the cost of the apparatus. When the window screen is displayed, a range of the road map including at least a range of the road map displayed in the base screen is displayed in the window screen, and an indication representing the range of the road map displayed in the base screen is displayed in the window screen.

Abstract: A map display apparatus for a motor vehicle comprising: road map storage device which stores road map data relating to a road map; a display device capable of displaying the road map; bird's-eye view data converting circuit which converts the road map data into bird's-eye view data so that a bird's-eye view taken by obliquely looking down the road map from above is displayed on the display device; and display control circuit which displays a plurality of grid lines such that the grid lines are superposed on the bird's-eye view.

Abstract: A reckoning system capable of determining a current location with reliability higher than a desired level by employing both the radio reckoning and the self reckoning which compensate for each other. Vehicle-speed sensor and gyroscope provide a first provisional current location of a vehicle. A second provisional current location is provided by correcting the first provisional current location in comparison with road map information stored in a CD-ROM. A third provisional current location is obtained on the basis of information from a GPS receiver. If the second and third provisional current locations are close with each other within a predetermined distance, then the second provisional current location is selected as a conclusive current location. If not, speed and heading of the vehicle derived from the GPS receiver are compared with those derived from the vehicle-speed sensor and the gyroscope, respectively.

Abstract: A navigation system in which a more preferable path can be quickly searched for by using map data in a form easy of maintenance, and which is well suited for installation on a vehicle. A map data memory unit stores therein the road data of roads which belong to management areas, for each of the management areas of predetermined extent and shape and for each of hierarchies corresponding to sorts of the roads. A path search/guidance control unit searches for the path which extends from a current point decided by a positioning unit, to a destination point set by a set input unit.

Abstract: In a case where a flag delivered from a self-contained navigation processor indicates that a position measured by the self-contained navigation processor lies on or in the vicinity of a road contained in road map information, a position correction processor selects and delivers the measured position of the self-contained navigation processor as an output current position. In any other case, the position correction processor calculates the distance between a position measured by a radio navigation processor and the position measured by the self-contained navigation processor. On condition that the distance between the coordinates of the two positions has, at least, a predetermined value, the position correction processor decides the measured position of the radio navigation processor as a current position, and it corrects to the current position a drive starting coordinate point which is managed by the self-contained navigation processor.