Electronic map apparatus and electronic map display method

Abstract

In an electronic map apparatus, an electronic map is displayed in accordance with map data read out from a DVD-ROM. Then, distance display circles which have a common center located at a point on the electronic map and each interconnect points on the electronic map at equal geographical distances from the point are drawn. As a result, it is possible to know an approximate geographical distance to a destination intuitively and easily in the electronic map apparatus which is typically used for car navigation.

1 . An electronic map apparatus comprising:
 data fetching means for fetching map data from media for storing said map data to be displayed as a map;   a display device for displaying said map in accordance with said map data; and   a microcomputer for processing, to display said map in a perspective view, data of a circle or an arc which has a center at a specified point on said map and links points on said map at equal geographical distances from said center.   
   
   
       2 . An electronic map apparatus comprising:
 data fetching means for fetching map data from media for storing said map data to be displayed as a map;   a display device for displaying said map in accordance with said map data; and   a microcomputer for processing data of a circle or an arc which has a center at a specified point on said map and links points on said map at equal geographical distances from said center,   wherein said circle or said arc is displayed on said map displayed on said display device in a perspective view in accordance with said data processed by said microcomputer when said map is displayed on said display device.   
   
   
       3 . An electronic map apparatus according to  claim 2 , wherein said microcomputer processes data of a plurality of said circles or said arcs representing different geographical distances from said center and said circles or said arcs are each superposed on said map displayed in a perspective view. 
   
   
       4 . An electronic map apparatus according to  claim 3 , wherein said microcomputer outputs numbers each indicating a geographical distance from said center to one of said circles or said arcs and displays each of said numbers at a location in close proximity to the circumference of said circle or said arc with a geographical distance thereof indicated by said number. 
   
   
       5 . An electronic map apparatus according to  claim 3 , wherein said microcomputer changes contraction of a map displayed on said display device in a perspective view and modifies said geographical distances from said center to said circles or said arcs and the number of said circles or said arcs in accordance with a degree of contraction of said map. 
   
   
       6 . An electronic map apparatus according to  claim 2 , wherein: said electronic map apparatus is a navigation apparatus mounted on a vehicle; said specified point is the position of said vehicle; map data of a map including said position of said vehicle is read out from said media; and said map is displayed in a perspective view in accordance with said map data read out from said media. 
   
   
       7 . An electronic map apparatus according to  claim 2 , wherein said specified point is a point on a map specified by a user. 
   
   
       8 . An electronic map apparatus according to  claim 1 , wherein said map is displayed in a perspective view, and a character or a symbol representing a direction is displayed at said specified point. 
   
   
       9 . An electronic map display method comprising the steps of:
 fetching map data from predetermined media for storing said map data to be displayed as a map;   displaying said map on a display device in a perspective view in accordance with said map data; and   displaying a circle or an arc, which has a center at a specified point on said map and links points on said map at equal geographical distances from said center, on said map displayed on a display device in a perspective view.   
   
   
       10 . An electronic map display method according to  claim 9 , wherein a plurality of said circles or said arcs representing different geographical distances from said center each displayed on said map displayed in a perspective view. 
   
   
       11 . An electronic map display method according to  claim 10 , wherein numbers each indicating a geographical distance from said center to one of said circles or said arcs are displayed at a location in close proximity to the circumference of said circle or said arc. 
   
   
       12 . An electronic map display method according to  claim 10 , wherein said geographical distances from said center to said circles or said arcs and the number of said circles or said arcs are changed in accordance with a degree of contraction of said map. 
   
   
       13 . An electronic map display method according to  claim 9 , wherein: the position of a vehicle on which a navigation apparatus is mounted is specified as said specified point; map data of a map including said position of said vehicle is read out from said media; and said map is displayed in a perspective view in accordance with said map data read out from said media. 
   
   
       14 . An electronic map display method according to  claim 9 , wherein a point on a map is specified by a user as said specified point. 
   
   
       15 . An electronic map display method according to  claim 9 , wherein said map is displayed in a perspective view, and a character or a symbol representing a direction is displayed at said specified point.