Map display device, navigation device and map display method

• US 6,169,552 B1
• Filed: 04/15/1997
• Issued: 01/02/2001
• Est. Priority Date: 04/16/1996
• Status: Expired due to Term

• Current Assignee: Clarion Co., Ltd. (Faurecia SA)
• Original Assignee: Xanavi Informatics Corporation (Hitachi, Ltd.)
• Inventors: Endo, Yoshinori, Okude, Mariko
• Primary Examiner(s): Zimmerman, Mark
• Assistant Examiner(s): Nguyen, Kimbinh T.
• Application Number:
  US08/839,611
• Time in Patent Office: 1,358 Days
• Field of Search: 345/133, 345/139, 345/419, 345/421, 345/425, 345/427, 701/200
• US Class Current: 345/427
• CPC Class Codes: G01C 21/3638 including 3D objects and buildings three dimensional [3D] modelling, e.g. data description of 3D objects G06T17/00; geographic models G06T17/05
• CPC Class Codes: G01C 21/3848 Data obtained from both position sensors and additional sensors
• CPC Class Codes: G01C 21/3852 Data derived from aerial or satellite images
• CPC Class Codes: G01C 21/3867 Geometry of map features, e.g. shape points, polygons or for simplified maps
• CPC Class Codes: G08G 1/0967 Systems involving transmission of highway information, e.g. weather, speed limits transmission of navigation instructions to the vehicle G08G1/0968
• CPC Class Codes: G08G 1/0969 having a display in the form of a map

Abstract

There is provided a map display device and a navigation device for displaying a three-dimensional map in which information which is originally hidden can be displayed on a display frame (screen). The map display device (navigation device) includes a map storing unit for storing three-dimensional data of each map constituent, and a map display unit for forming a three-dimensional bird'"'"'s-eye view map which is obtained by projecting onto the plane from a desired view point each map constituent which is specified by the three-dimensional data stored in the map storing unit, and displaying the three-dimensional bird'"'"'s-eye view map thus formed on a display frame (screen). When information which is requested to be displayed by a user is hidden by another map constituent located in front of the information and thus is not originally displayed on the three-dimensional bird'"'"'s-eye view map, the map display unit changes a projection mode for projecting the information or the other map constituent on the plane so that the information is displayed on the display frame.

Claims

1. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed;

a view point determining unit for determining a view point on the basis of the position of the vehicle detected by the vehicle position detecting unit; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from the view point determined by the view point determining unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes;

a hiding determining means for determining whether, in three dimensional space, the mark is hidden by a map constituent located nearer the viewpoint than the mark so that there is no direct line of sight between the view point and the mark and the mark is not normally displayed on the three-dimensional bird'"'"'s-eye view map; and

a projection mode changing means for automatically changing a projection mode of the mark or the map constituent so that the mark is displayed on the display frame even though the mark is not in a direct line of sight from the view point,

wherein the projection mode is automatically changed only if the hiding determining means determines that the mark is hidden by the map constituent.

2. The navigation device as claimed in claim 1, further comprising a navigation information setting unit for setting, on a first map constituent, navigation information such as a landmark, a destination point, or a route to the destination point,

wherein said hiding determining means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and said projection mode changing means changes a projection mode of the first map constituent or the second map constituent so that the first map constituent is displayed on the display frame when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

3. The navigation device as claimed in claim 2, wherein said projection mode changing means performs a-blending processing between the first map constituent and the second map constituent to display the first map constituent while the second map constituent is seen through, when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

4. The navigation device as claimed in claim 3, wherein said projection mode changing means changes the projection mode of the first map constituent so that the first map constituent is displayed in front of the second map constituents when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

5. The navigation device as claimed in claim 4, wherein said projection mode changing means changes a display attribute of a part of the first map constituent so that the part of the first map constituent is displayed with a predetermined pattern, color or line type, when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

6. The navigation device as claimed in claim 2, wherein said projection mode changing means changes the projection mode of the second map constituent so that the second map constituent is not projected onto the plane, when the hiding determining means determines that the first map constituent is hidden by the second map constitutent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

7. The navigation device as claimed in claim 6, wherein said projection mode changing means projects onto the plane an area occupied by the second map constituent on the ground plane in place of the projection of the second map constituent, when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

8. The navigation device as claimed in claim 6, wherein said projection mode changing means displays a name of the second map constituent on the three-dimensional bird'"'"'s-eye view map in place of the second map constituent, when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

9. The navigation device as claimed in claim 2, wherein said projection mode changing means changes the projection mode of the first map constituent or the second map constituent so that the first map constituent is displayed on the display frame, when the hiding determining means determines that the first map constituent is hidden by the second map constituent and a ratio of an area of a part of the first map constituent hidden by the second map constituent to a whole area of the first map constituent is lager than a predetermined value.

10. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the thee-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed;

a view point determining unit for determining a first view point on the basis of the position of the vehicle detected by the vehicle position detecting unit; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from the first view point determined by the view point determining unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes;

a hiding determining means for determining whether. in three dimensional space, the mark is hidden by a map constituent located nearer the first view point than the mark so that there is no direct line of sight between the view point and the mark and the mark is not displayed on the three-dimensional bird'"'"'s-eye view map; and

a view point changing means for automatically switching from the first view point to a second view point which has a direct line of sight to the mark so that the mark is displayed on the three-dimensional bird'"'"'s-eye view map,

wherein the automatic switching takes place only if the hiding determining means determines that the mark is hidden by the map constituent.

11. The navigation device as claimed in claim 10, further comprising a navigation information setting unit for setting, on a first map constitutent, navigation information such as a landmark, a destination point, or a route to the destination point, wherein said hiding determining means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and said view point changing means changes a position of the view-point to a position where the first map constituent is displayed on the three-dimensional bird'"'"'s-eye view map when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

12. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed;

a view point determining unit for determining a view point on the basis of the position of the vehicle detected by the vehicle position detecting unit; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from the view point determined by the view point determining unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame, wherein said map display unit includes;

a hiding determining means for determining whether, in three dimensional space, the mark is hidden by a map constituent located nearer the view point than the mark so that there is no direct line of sight between the view point and the mark and the mark is not displayed on the three-dimensional bird'"'"'s-eye view map; and

a two-dimensional map display means for automatically forming a two-dimensional map on the basis of the two-dimensional data of each map constituent and automatically displaying the two-dimensional map with the mark on the display frame in place of the three-dimensional bird'"'"'s-eye view map,

wherein the two-dimensional map is automatically formed and displayed only if the hiding determining means determines that the mark is hidden by the map constituent.

13. The navigation device as claimed in claim 12, further comprising a navigation information setting unit for setting navigation information with regard to a first map constituent, such as a landmark, a destination point, or a route to the destination point,

wherein said hiding determining means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and said two-dimensional map display means forms a two-dimensional map on the basis of the two-dimensional data of each map constituent to display the two-dimensional map on the display frame in place of the three-dimensional bird'"'"'s-eye view map when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

14. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed;

a view point determining unit for determining a view point on the basis of the position of the vehicle detected by the vehicle position detecting unit; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from the view point determined by the view point determining unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes;

a hiding determining means for determining whether, in three dimensional space, the mark is hidden by a map constituent located nearer the view point than the mark so that there is no direct line of sight between the view point and the mark and the mark is not displayed on the three-dimensional bird'"'"'s-eye view map; and

a two-dimensional bird'"'"'s-eye view map display means for automatically forming on the basis of the two-dimensional data of each map constituent, a two-dimensional bird'"'"'s-eye view map obtained by viewing a two-dimensional map from the view point, and automatically displaying the two-dimensional bird'"'"'s-eye view map with the mark on the display frame in place of the three-dimensional bird'"'"'s-eye view map,

wherein the two-dimensional bird'"'"'s eye view map is automatically formed and displayed only if the hiding determining means determines that the mark is hidden by the map constituent.

15. The navigation device as claimed in claim 14, further comprising a navigation information setting unit for setting, on a first map constituent, navigation information such as a landmark, a destination point, or a road to the destination point, wherein said hiding determining means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and said two-dimensional bird'"'"'s-eye view map display means forms on the basis of the two-dimensional data of each map constituent, a two-dimensional bird'"'"'s-eye view map obtained by viewing a two-dimensional map from the view point, to display the two-dimensional bird'"'"'s-eye view map on the display frame in place of the three-dimensional bird'"'"'s-eye view map when the hiding determining means determines that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

16. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from a view point, which is determined on the basis of the position of the vehicle detected by the vehicle position detecting unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes a duplicative display means for deciding whether or not the mark is hidden by a map constituent located nearer the view point than the mark so that the mark is not displayed on the three-dimensional bird'"'"'s-eye view map, and for forming a two-dimensional map on the basis of the two-dimensional data of each map constituent to display the two-dimensional map with the mark on the display frame together with the three-dimensional bird'"'"'s-eye view map when it is determined that the mark is hidden by the map constituent and thus the mark is not displayed on the three-dimensional bird'"'"'s-eye view map.

17. The navigation device as claimed in claim 16, further comprising a navigation information setting unit for setting navigation information indicating a first map constituent such as a landmark, a destination point, or a road to the destination point,

wherein said duplicative display means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and forms a two-dimensional map on the basis of the two-dimensional data of each map constituent to display the two-dimensional map on the display frame together with the three-dimensional bird'"'"'s-eye view map when it is determined that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

18. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from a view point, which is determined on the basis of the position of the vehicle detected by the vehicle position detecting unit, to form a three-dimensional bird'"'"'s-eye view map, and displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes a duplicative display means for determining whether or not the mark is hidden by a map constituent located nearer the view point than the mark so that the mark is not displayed on the three-dimensional bird'"'"'s-eye view map, and for forming on the basis of the two-dimensional data of each map constituent, a two-dimensional bird'"'"'s-eye view map obtained by viewing a two-dimensional map from the view point, to display the two-dimensional bird'"'"'s-eye view map with the mark on the display frame together with the three-dimensional bird'"'"'s-eye view map when it is determined that the mark is hidden by the map constituent and thus the mark is not displayed on the three-dimensional bird'"'"'s-eye view map.

19. The navigation device as claimed in claim 18, further comprising a navigation information setting unit for setting navigation information indicating a first map constituent such as a landmark, a destination point, or a road to the destination point,

wherein said duplicative display means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and forms on the basis of the two-dimensional data of each map constituent, a two-dimensional bird'"'"'s-eye view map obtained by viewing a two-dimensional map from the view point, to display the two-dimensional bird'"'"'s-eye view map on the display frame together with the three-dimensional bird'"'"'s-eye view map when it is determined that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

20. A navigation device for displaying a three-dimensional map on a display frame, comprising:

a map storage unit for storing three-dimensional data of plural map constituents which constitute the three-dimensional map;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed; and

a map display unit for projecting a mark showing the position of the vehicle detected by the vehicle position detecting unit and each map constituent specified by the three-dimensional data stored in said map storage unit onto a plane from a view point, which is determined on the basis of the position of the vehicle detected by the vehicle position detecting unit, to form a first three-dimensional bird'"'"'s-eye view map, and displaying the first three-dimensional bird'"'"'s-eye view map on the display frame,

wherein said map display unit includes duplicative display means for determining whether or not the mark is hidden by a map constituent located nearer the view point than the mark so that the mark is not displayed on the three-dimensional bird'"'"'s-eye view map, and for forming a second three-dimensional bird'"'"'s-eye view map obtained by projecting the mark showing the position of the vehicle and each of the map constituents onto a plane from a view point where the mark showing the position of the vehicle can be viewed, to display the second three-dimensional bird'"'"'s-eye view map on the display frame together with the first three-dimensional bird'"'"'s-eye view map when it is determined that the mark is hidden by the map constituent and thus the mark is not displayed on the three-dimensional bird'"'"'s-eye view map.

21. The navigation device as claimed in claim 20, further comprising a navigation information setting unit for setting navigation information indicating a first map constituent such as a landmark, a destination point, or a road to the destination point,

wherein said duplicative display means determines whether or not the first map constituent is hidden by a second map constituent located nearer the view point than the first map constituent so that the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map, and forms the second three-dimensional bird'"'"'s-eye view map obtained by projecting the mark showing the position of the vehicle and each of the map constituents onto a plane from a view point where the first map constituent can be viewed, to display the second three-dimensional bird'"'"'s-eye view map on the display frame together with the first three-dimensional bird'"'"'s-eye view map when it is determined that the first map constituent is hidden by the second map constituent and thus the first map constituent is not displayed on the three-dimensional bird'"'"'s-eye view map.

22. A map display method for displaying a three dimensional map on a display frame, comprising steps of:

detecting a position of a vehicle;

determining a view point on the basis of the detected position of the vehicle;

forming a three-dimensional map in which a mark showing the detected position of the vehicle and map constituents are arranged on a three-dimensional coordinate system, on the basis of the detected position of the vehicle and three-dimensional data of plural map constituents stored in storing unit;

projecting the mark and the map constituent arranged on the three-dimensional coordinate system onto a plane from the determined view point to form a three-dimensional bird'"'"'s-eye view map;

displaying the three-dimensional bird'"'"'s-eye view map on the display frame,

determining whether, in three dimensional space, the mark is hidden by a map constituent located nearer the view point than the mark such that there is no direct line of sight between the view point and the mark, and

automatically changing a projection mode of the mark or of the map constituent behind which the mark is hidden so that the mark is displayed on the display frame even though there is no direct line of sight from the view point to the mark,

wherein the projection mode is automatically changed only if the hiding determining means determines that the mark is hidden by the map constituent.

23. A navigation device for displaying a three dimensional map on a display frame, comprising:

a map storing unit for storing three-dimensional data of plural map constituents which constitute the three dimensional map;

an appendant information storing unit for storing appendant information of the map constituents stored in said map storing unit;

a vehicle position detecting unit for detecting a position of a vehicle in which the navigation device is installed;

a three-dimensional map forming unit for forming a three-dimensional map, in which the map constituents are arranged on a three-dimensional coordinate system, on the basis of the three-dimensional data stored in said map storing unit;

a projection map forming unit for forming a projection map which is obtained by viewing the three-dimensional map formed by said three-dimensional map forming unit from a view point which is determined on the basis of the position of the vehicle detected by the vehicle position detecting unit;

a read-out unit for reading out the appendant information corresponding to the map constituent which is arranged on the three-dimensional coordinate system by said three-dimensional map forming unit;

a visible area detection unit for detecting a visible area on the projection map of the map constituent corresponding to the appendant information read out by said read-out unit;

a display area setting unit for setting a display area on the projection map of the appendant information read out by said read-out unit, on the basis of the visible area of the map constituent corresponding to the appendant information read out by said read-out unit;

an adding unit for adding the appendant information read out by said read-out unit onto the display area thereof which is set by said display area setting unit; and

a display unit for displaying on the display frame the projection map which is added with the appendant information by said adding unit.

24. The navigation device as claimed in claim 23, wherein said display area setting means sets the display area of the appendant information read out by said read-out unit, within the visible area of the map constituent corresponding to the appendant information read out by said read-out unit.

25. The navigation device as claimed in claim 24, wherein said adding unit has layout setting means for setting a layout of the appendant information read out by said read-out unit so that the appendant information is accommodated within the display area of the appendant information which is set by said display area setting unit.

26. The navigation device as claimed in claim 24, wherein said display area setting unit keeps the display area of the appendant information read out by said read-out unit as it is, even in such a case that the visible area of the map constituent corresponding to the appendant information read out by said read-out unit enlarges according to the view point changed by the position of the vehicle detected by the vehicle position detecting unit.

27. The navigation device as claimed in claim 24, wherein, in a case that the visible area of the map constituent corresponding to the appendant information read out by said read-out unit is changed according to the view point changed by the position of the vehicle detected by the vehicle position detecting unit, if the display area of the appendant information set before the visible area of the map constituent corresponding to the appendant information is changed, is accommodated within the changed visible area of the map constituent corresponding to the appendant information, said display area setting unit keeps the display area of the appendant information as it is, and if the display area of the appendant information set before the visible area of the map constituent corresponding to the appendant information is changed, is not accommodated within the changed visible area of the map constituent corresponding to the appendant information, said display area setting means updates the display area of the appendant information so that the display area of the appendant information is accommodated within the changed visible area of the map constituent corresponding to the appendant information.

28. The navigation device as claimed in claim 24, further comprising a judgment unit for judging whether the appendant information added onto the display area thereof which is set by said display area setting unit can be displayed in a predetermined or larger size, wherein if said judgment unit judges that the appendant information cannot be displayed in the predetermined or larger size, said display area setting unit resets the display area of the appendant information in the neighborhood of the visible area of the map constituent corresponding to the appendant information.

29. The navigation device as claimed in claim 28, further comprising an overlap detection unit for detecting the overlap between the appendant information concerned and appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned on the projection map which is added with the appendant information by said adding means, wherein when said overlap detection unit detects the overlap, said display area setting unit resets the display area of the appendant information so that the appendant information is not overlapped with appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned.

30. The navigation device as claimed in claim 28, further comprising an overlap detection unit for detecting the overlap between the appendant information concerned and appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned on the projection map which is added with the appendant information by said adding unit, and a priority order determining unit for determining priority order for the display of the overlap-detected appendant information or map constituents on the display frame when the overlap is detected by said overlap detection means, wherein said display unit displays on the display frame the appendant information or map constituent having the highest priority determined by said priority order determining unit among the overlap-detected appendant information and map constituents.

31. The navigation device as claimed in claim 30, wherein said priority order determining unit determines the priority order on the display frame on the basis of the map constituent corresponding to the appendant information for which the overlap is detected by said overlap detection unit or the arrangement position on the three-dimensional map of the map constituent for which the overlap is detected by said overlap detection unit.

32. The navigation device as claimed in claim 30, wherein said priority order determining unit determines the priority order on the display frame on the basis of the map constituent corresponding to the appendant information for which the overlap is detected by said overlap detection unit or the type of map constituent for which the overlap is detected by said overlap detection unit.

33. The navigation device as claimed in claim 23, wherein said display area setting unit sets the display area of the appendant information corresponding to a map constituent in the neighborhood of the visible area of the map constituent detected by said visible area detection unit.

34. The navigation device as claimed in claim 33, further comprising an overlap detection unit for detecting an overlap between the appendant information concerned and appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned on the projection map which is added with the appendant information by said adding unit, wherein when the overlap is detected by said overlap detection unit, said display area setting unit resets the display area of the appendant information so that the appendant information is not overlapped with appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned.

35. The navigation device as claimed in claim 33, further comprising:

an overlap detection unit for detecting an overlap between the appendant information concerned and appendant information other than the appendant information concerned or map constituents other than the map constituent corresponding to the appendant information concerned on the projection map which is added with the appendant information by said adding unit, and an priority order determining unit for determining the priority order for the overlap-detected appendant information or map constituent on the display frame when the overlap is detected by said overlap detection unit, wherein said display unit displays on the display frame the appendant information or map constituent having the highest priority determined by said priority order determining unit among the overlap-detected appendant information and map constituents.

36. The navigation device as claimed in claim 35, wherein said priority order determining unit determines the priority order on the display frame on the basis of the map constituent corresponding to the appendant information for which the overlap is detected by said overlap detection unit or the arrangement position on the three-dimensional map of the map constituent for which the overlap is detected by said overlap detection unit.

37. The navigation device as claimed in claim 35, wherein said priority order determining unit determines the priority order on the display frame on the basis of the map constituent corresponding to the appendant information for which the overlap is detected by said overlap detection unit or the type of map constituent for which the overlap is detected by said overlap detection unit.

38. A map display method for displaying a three dimensional map on a display frame, comprising steps of:

on the basis of three-dimensional data of plural map constituents stored in storing unit, forming a three-dimensional map in which the map constituents are arranged on a three-dimensional coordinate system;

forming a projection map which is obtained by viewing the three-dimensional map from a view-point;

reading out, from an appendant information storing unit for storing appendant information of the map constituents stored in said map storing unit, the appendant information corresponding to the map constituent which is arranged on the three-dimensional coordinate system;

detecting a visible area on the projection map of the map constituent displayed on the projection map;

on the basis of the detected visible area, setting a display area on the projection map of the appendant information corresponding to the map constituent concerned;

adding the appendant information onto the display area of the appendant information concerned; and

displaying the projection map added with the appendant information concerned on the display frame.