Map Display Device And Map Display Method

• US 20080306684A1
• Filed: 05/21/2008
• Published: 12/11/2008
• Est. Priority Date: 06/06/2007
• Status: Active Grant

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Original Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Inventors: Yamazaki, Noboru
• Granted Patent: US 8,781,734 B2
• Time in Patent Office: Days
• US Class Current: 701/208
• CPC Class Codes: G01C 21/3673 Labelling using text of road map data items, e.g. road names, POI names

Abstract

The invention provides a map display device and map display method that enhance the information density of displayed road names while maintaining legibility of a map image. First, the map drawing unit draws, to an image storage unit, a map image of roads and so forth in a desired scale, by using the background layer of a first hierarchy corresponding to the desired scale. Second, the map drawing unit draws place names and facility names by using the character layer of the first hierarchy to superimpose them on the map image. Third, the map drawing unit extracts the road names that do not overlap with the map characters of the place names and facility names on the map image by using the character layer of the first hierarchy, and superimposes them on the map image at the normal character size. Fourth, the map drawing unit extracts, by using the character layer of a second hierarchy corresponding to a scale level smaller by one step than the desired scale level, road names that do not overlap with the map characters of the other road names, place names, facility names and so forth on the map image, and superimposes them on the map image at a smaller character size. Finally, the map drawing unit superimposes the vehicle position mark on the map image.

Claims

1. A map display method using map data that is provided for each of plural hierarchies corresponding to plural scales and which comprises map character data including road names, for generating and displaying a map image with map characters including the road names at a desired scale, comprising:

drawing the map image with the map characters including road names of a predetermined character size of a first hierarchy corresponding to the desired scale by using the map data of the first hierarchy; and

adding road names of a second hierarchy at a smaller character size than the road names of the first hierarchy on the map image, by using the map character data of the second hierarchy which is at a scale larger by one step than the first hierarchy.

2. A map display method according to claim 1, wherein the method:

avoids drawing a road name of the first hierarchy if it overlaps with other road names of the first hierarchy on the map image; and

avoids drawing a road name of the second hierarchy if it overlaps with the other road names of the second hierarchy on the map image.

3. A map display method according to claim 1, wherein the method avoids drawing a road name of the second hierarchy if the road name of the second hierarchy overlaps with any road name of the first hierarchy on the map image.

4. A map display method according to claim 1, wherein one of the overlapping parts where road names of the first and second hierarchies overlap is superimposed on the other with transparent characters.

5. A map display method according to claim 1, wherein the method avoids drawing a road name of the second hierarchy if the road name of the second hierarchy duplicates a road name of the first hierarchy.

6. A map display method according to claim 1, further comprising:

including one or more other items including place names or facility names within the map character data of each hierarchy;

and for displaying the map image,

if a road name of the first hierarchy overlaps on the map image with a map character other than the road names of the first hierarchy, not drawing the road name; and

if a road name of the second hierarchy overlaps on the map image with a map character other than the road names of the first hierarchy, not drawing the road name.

7. A map display method according to claim 6, wherein, when drawing the map image by rotating the upward direction by a given angle with respect to a predetermined reference direction, the map characters of at least some of the items other than the road names of the first hierarchy are drawn laterally.

8. A map display method according to claim 6, wherein, when drawing the map image by rotating the upward direction by a given angle with respect to a predetermined reference direction, the road names of the first and second hierarchies are drawn by rotating the normal character patterns by the given angle.

9. A map display device that displays a map image surrounding a vehicle position, comprising:

a map data storage unit storing map data that is provided for each of plural hierarchies corresponding to plural scales and which comprises map character data including road names; and

a map drawing controlling means that generates a map image with map characters including the road names at a desired scale by using the map data and displays it on a display means,

wherein the map drawing controlling means draws the map image with the map characters including road names of a predetermined character size of a first hierarchy corresponding to the desired scale by using the map data of the first hierarchy, and adds road names of a second hierarchy at a smaller character size than the road names of the first hierarchy on the map image, by using the map character data of the second hierarchy which is at a scale larger by one step than the first hierarchy.

10. A map display device according to claim 9, wherein:

if a road name of the first hierarchy overlaps with other road names of the first hierarchy on the map image, the map drawing controlling means avoids drawing the road name; and

if a road name of the second hierarchy overlaps with other road names of the second hierarchy on the map image, the map drawing controlling means avoids drawing the road name.

11. A map display device according to claim 9, wherein, if a road name of the second hierarchy overlaps with road names of the first hierarchy on the map image, the map drawing controlling means avoids drawing the road name of the second hierarchy.

12. A map display device according to claim 9, wherein the map drawing controlling means draws one of the parts where road names of the first and second hierarchies overlap with transparent characters.

13. A map display device according to claim 9, wherein, if there is a road name of the second hierarchy on the map image that duplicates a road name of the first hierarchy, the map drawing controlling means avoids drawing the road name of the second hierarchy.

14. A map display device according to claim 9, wherein the map character data of each hierarchy comprises one or more other items including place names or facility names, and, when displaying the map image, if a road name of the first hierarchy overlaps on the map image with a map character other than the road names of the first hierarchy, the map drawing controlling means avoids drawing the road name, and if a road name of the second hierarchy overlaps on the map image with a map character other than the road names of the first hierarchy, the map drawing controlling means avoids drawing the road name.

15. A map display device according to claim 14, wherein, when drawing the map image by rotating the upward direction by a given angle with respect to a predetermined reference direction, the map drawing controlling means draws the map characters of at least some of the items other than the road names of the first hierarchy laterally.

16. A map display device according to claim 14, wherein, when drawing the map image by rotating the upward direction by a given angle with respect to a predetermined reference direction, the map drawing controlling means draws the road names of the first and second hierarchies by rotating the normal character patterns by the given angle.