Map display device, map display method, and computer program for use in map display device

• US 6,650,253 B2
• Filed: 05/29/2001
• Issued: 11/18/2003
• Est. Priority Date: 05/30/2000
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mochizuki, Yoshiyuki, Nishimura, Kenji, Senda, Keiichi
• Primary Examiner(s): PHAM, TOAN NGOC
• Application Number:
  US09/867,112
• Publication Number:
  US 20010048377A1
• Time in Patent Office: 903 Days
• Field of Search: 340/995.1, 340/995.14, 340/995.15, 340/995.17, 340/995.26, 340/995.28, 701/200, 701/212
• US Class Current: 340/995.1
• CPC Class Codes: G01C 21/3635 Guidance using 3D or perspective road maps
• CPC Class Codes: G09B 29/10 Map spot or coordinate position indicators; Map reading aids optical projection apparatus per se G03B

Abstract

In a map display device, a surface storing unit stores surface information which defines a curved surface having a form that depends on positions of portions of a map which are to be enlarged and/or contracted. A mapping unit maps the map onto the curved surface defined by the surface information. A projecting/displaying unit projects the mapped map onto a flat virtual screen, and displays the projected image. Here, by defining the curved surface so that each part of the curved surface forms an intended angle with a line of sight in the projection, the image is displayed with desired portions enlarged and/or contracted, while maintaining connections of roads. The same effect can also be achieved by projecting the map onto a virtual screen having the form of the curved surface.

Claims

1. A map display device, comprising:

map storing means for storing map information;

map acquiring means for acquiring map information that shows the a map of an area specified by a current position of the map display device, from the map storing means, the map having a portion which is to be enlarged and/or a portion which is to be contracted, the portion to be enlarged and the portion to be contracted being referred to as an enlarged portion and a contracted portion respectively;

surface storing means for storing surface information that defines a curved surface whose form depends on a positioning of the enlarged portion and/or the contracted portion on the map shown by the acquired map information;

mapping means for mapping the map shown by the acquired map information, onto the curved surface defined by the surface information, to generate the a mapped image; and

projecting/displaying means for projecting the mapped image onto a flat virtual screen, and displaying the projected image.

2. The map display device of claim 1,

wherein the curved surface defined by the surface information has the following property:

when the map is mapped onto the curved surface by the mapping means and projected onto the virtual screen by the projecting/displaying means,

(a) an angle formed between a part of the curved surface to which the enlarged portion of the map is mapped and a line of sight directed to the part of the curved surface in the projection is larger than any angles formed between other parts of the curved surface and lines of sight directed to the other parts of the curved surface in the projection, and

(b) an angle formed between a part of the curved surface to which the contracted portion of the map is mapped and a line of sight directed to the part of the curved surface in the projection is smaller than any angles formed between other parts of the curved surface and lines of sight directed to the other parts of the curved surface in the projection.

3. The map display device of claim 2, further comprising

altitude storing means for storing altitude information showing a correspondence between positions of points shown in the map and altitudes of the points,

the mapping means includes

a surface deforming unit for providing undulations corresponding to the altitudes shown by the altitude information, to the curved surface at positions to which the points on the map at the corresponding positions shown by the altitude information are to be mapped, to generate a deformed curved surface, and

the mapping means maps the map onto the deformed curved surface.

4. The map display device of claim 3,

wherein the surface deforming unit includes

an altitude changing unit for changing altitudes in the altitude information that correspond to positions included in a first area which is made up of the current position of the map display device in the map and a neighborhood thereof, to a uniform value, and

the surface deforming unit generates the deformed curved surface, using the changed altitude information.

5. The map display device of claim 4,

wherein the altitude changing unit further changes altitudes in the altitude information that correspond to positions included in an area around the first area, in accordance with distances of the positions from the first area.

6. The map display device of claim 1, further comprising

surface receiving means for receiving the surface information,

wherein the surface storing means stores the surface information received by the surface receiving means.

7. The map display device of claim 1,

wherein the projecting/displaying means includes

a projection position storing unit for storing a correspondence between positions on the curved surface and positions on the virtual screen to which points at the positions on the curved surface are to be projected.

8. The map display device of claim 1,

wherein the map information stored in the map storing means includes (a) image information showing an image in which graphics representative of objects are drawn in correspondence with positions of the objects on the ground surface, and (b) character information showing a correspondence between character strings relating to the objects and the positions of the objects on the ground surface,

the map acquiring means acquires image information and character information which relate to the map of the area specified by the current position of the map display device, from the map storing means,

the map display device further comprises

character display position calculating means for calculating points on the curved surface to which points on the map at positions shown by the acquired character information are mapped, and calculating positions on the virtual screen to which the calculated points on the curved surface are projected,

the mapping means maps an image shown by the acquired image information, to generate the mapped image, and

the projecting/displaying means further displays character strings shown by the acquired character information, with reference to the calculated positions.

9. The map display device of claim 1 being mounted on a movable body, and further comprising

positional information receiving means for receiving positional information showing a current position and a traveling direction of the movable body,

wherein the map acquiring means acquires the map information showing the map of the area specified by the positional information received by the positional information receiving means, from the map storing means.

10. The map display device of claim 9, further comprising

map receiving means for receiving map information transmitted by radio,

wherein the map storing means stores the map information received by the map receiving means.

11. A map display device, comprising:

map storing means for storing map information;

map acquiring means for acquiring map information that shows a map of an area specified by a current position of the map display device, from the map storing means, the map having a portion which is to be enlarged and/or a portion which is to be contracted, the portion to be enlarged and the portion to be contracted being referred to as an enlarged portion and a contracted portion respectively;

surface storing means for storing surface information that defines a virtual screen having a form of a curved surface which depends on a positioning of the enlarged portion and/or the contracted portion on the map shown by the acquired map information; and

projecting/displaying means for projecting the map shown by the acquired map information onto the virtual screen defined by the surface information, and displaying a projected image obtained as a result of the projection.

12. The map display device of claim 11,

wherein the virtual screen defined by the surface information has the following property:

when the map is projected onto the virtual screen by the projecting/displaying means,

(a) an angle formed between a part of the virtual screen to which the enlarged portion of the map is projected and a line of sight directed to the part of the virtual screen in the projection is smaller than any angles formed between other parts of the virtual screen and lines of sight directed to the other parts of the virtual screen in the projection, and

(b) an angle formed between a part of the virtual screen to which the contracted portion of the map is projected and a line of sight directed to the part of the virtual screen in the projection is larger than any angles formed between other parts of the virtual screen and lines of sight directed to the other parts of the virtual screen in the projection.

13. The map display device of claim 12, further comprising

altitude storing means for storing altitude information showing a correspondence between positions of points shown in the map and altitudes of the points,

the projecting/displaying means includes

a map deforming unit for providing undulations corresponding to the altitudes shown by the altitude information, to the map at the corresponding positions shown by the altitude information, to generate a deformed map, and

the projecting/displaying means projects the deformed map onto the virtual screen.

14. The map display device of claim 13,

wherein the map deforming unit includes

an altitude changing unit for changing altitudes in the altitude information that correspond to positions included in a first area which is made up of the current position of the map display device in the map and a neighborhood thereof, to a uniform value, and

the map deforming unit generates the deformed map, using the changed altitude information.

15. The map display device of claim 14,

wherein the altitude changing unit further changes altitudes in the altitude information that correspond to positions included in an area around the first area, in accordance with distances of the positions from the first area.

16. The map display device of claim 11, further comprising

surface receiving means for receiving the surface information,

wherein the surface storing means stores the surface information received by the surface receiving means.

17. The map display device of claim 11,

wherein the projecting/displaying means includes

a projection position storing unit for storing a correspondence between positions on the map and positions on the virtual screen to which points at the positions on the map are to be projected.

18. The map display device of claim 11,

wherein the map information stored in the map storing means includes (a) image information showing an image in which graphics representative of objects are drawn in correspondence with positions of the objects on the ground surface, and (b) character information showing a correspondence between character strings relating to the objects and the positions of the objects on the ground surface,

the map acquiring means acquires image information and character information which relate to the map of the area specified by the current position of the map display device, from the map storing means,

the map display device further comprises

character display position calculating means for calculating positions on the virtual screen to which points on the map at positions shown by the acquired character information are to be projected, and

the projecting/displaying means projects an image shown by the acquired image information, to generate the projected image, and displays character strings shown by the acquired character information, with reference to the calculated positions.

19. The map display device of claim 11 being mounted on a movable body, and further comprising

positional information receiving means for receiving positional information showing a current position and a traveling direction of the movable body,

wherein the map acquiring means acquires the map information showing the map of the area specified by the positional information received by the positional information receiving means, from the map storing means.

20. The map display device of claim 19, further comprising

map receiving means for receiving map information transmitted by radio,

wherein the map storing means stores the map information received by the map receiving means.

21. A map display method for use in a map display device for displaying a map with one or more portions enlarged and/or contracted, comprising:

a map receiving step for receiving map information that shows a map of an area specified by a current position of the map display device, wherein surface information that defines a curved surface whose form depends on a positioning of one or more portions to be enlarged and/or contracted on the map shown by the map information is stored in a storing unit in the map display device;

a mapping step for mapping the map shown by the map information, onto the curved surface defined by the surface information, to generate a mapped image; and

a projecting/displaying step for projecting the mapped image onto a flat virtual screen, and displaying the projected image.

22. A map display method for use in a map display device for displaying a map with one or more portions enlarged and/or contracted, comprising:

a map receiving step for receiving map information that shows a map of an area specified by a current position of the map display device, wherein surface information that defines a virtual screen having a form of a curved surface which depends on a positioning of one or more portions to be enlarged and/or contracted on the map shown by the map information is stored in a storing unit in the map display device; and

a projecting/displaying step for projecting the map shown by the map information onto the virtual screen defined by the surface information, and displaying a projected image obtained as a result of the projection.

23. A computer program recorded on a computer-readable recording medium, for use in a map display device that displays a map with one or more portions enlarged and/or contracted, the program comprising:

a map receiving step for receiving map information that shows a map of an area specified by a current position of the map display device, wherein surface information that defines a curved surface whose form depends on a positioning of one or more portions to be enlarged and/or contracted on the map shown by the map information is stored in a storing unit in the map display device;

a mapping step for mapping the map shown by the map information, onto the curved surface defined by the surface information, to generate a mapped image; and

a projecting/displaying step for projecting the mapped image onto a flat virtual screen, and displaying the projected image.

24. A computer program recorded on a computer-readable recording medium, for use in a map display device that displays a map with one or more portions enlarged and/or contracted, the program comprising:

a map receiving step for receiving map information that shows a map of an area specified by a current position of the map display device, wherein surface information that defines a virtual screen having a form of a curved surface which depends on a positioning of one or more portions to be enlarged and/or contracted on the map shown by the map information is stored in a storing unit in the map display device; and

a projecting/displaying step for projecting the map shown by the map information onto the virtual screen defined by the surface information, and displaying a projected image obtained as a result of the projection.