Navigation system and method of displaying quasi-three-dimensional map information

• US 20020049532A1
• Filed: 09/19/2001
• Published: 04/25/2002
• Est. Priority Date: 09/27/2000
• Status: Active Grant

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Original Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Inventors: Nakamura, Hikaru
• Granted Patent: US 6,445,999 B1
• Time in Patent Office: Days
• US Class Current: 701/208
• CPC Class Codes: G01C 21/367 Details, e.g. road map scale, orientation, zooming, illumination, level of detail, scrolling of road map or positioning of current position marker

Abstract

In displaying map information, a map drawing unit generates map drawing data with an equal scale factor and a coordinate conversion unit does not execute coordinate conversion to an area a including the screen center and the lower area thereof, and writes in a VRAM the map drawing data that maintains the scale factor as it is. Further, the coordinate conversion unit writes in the VRAM map drawing data reduced with a specific reduction scale factor only in the horizontal direction as to each of the areas on the left and right of the area a; map drawing data reduced with a specific reduction scale factor only in the vertical direction as to the area directly above the area a; and map drawing data reduced with specific reduction scale factors both in the horizontal and vertical directions as to each of the areas located obliquely left above and obliquely right above the area a. Thus, the navigation system of the invention lightens the burden of calculation processing, displays detailed information of the most important area surrounding the vehicle position, and provides a seemingly bird'"'"'s-eye view display, namely, quasi-three-dimensional map information, that gives a user an extensive view.

Claims

1. A navigation system comprising:

a map data storage medium that stores map data having a uniform reduction scale factor for drawing map information;

a drawing memory corresponding to a display screen; and

a map drawing unit that reads map data from the map data storage medium, draws map information in the drawing memory with regard to a first area including a screen center and a lower part thereunder, and draws map information in the drawing memory with a smaller reduction scale factor than that in the first area, with regard to a second area surrounding the first area.

2. A navigation system as claimed in claim 1, wherein:

the first area is rectangular; and

the map drawing unit draws map information in the drawing memory with a reduction scale factor only in the horizontal direction with regard to areas on both sides relative to the first area, with a reduction scale factor only in the vertical direction with regard to an area above the first area, and with reduction scale factors in both the vertical and horizontal directions with regard to areas obliquely above the first area.

3. A navigation system as claimed in claim 2, wherein the reduction scale factor for the areas on both sides relative to the first area is different from the reduction scale factor for the area above the first area.

4. A navigation system as claimed in claim 2, wherein the reduction scale factor for the areas on both sides relative to the first area is equal to the reduction scale factor for the area above the first area.

5. A navigation system as claimed in claim 2, wherein the reduction scale factor for the area to the right of the first area is different from the reduction scale factor for the area to the left of the first area.

6. A navigation system as claimed in claim 2, wherein the map drawing unit divides the areas on both sides of the first area into plural areas, and with regard to the divided areas, sets the reduction scale factors gradually smaller as the divided areas become more distant from the first area.

7. A navigation system as claimed in claim 2, wherein the map drawing unit divides the area above the first area into plural areas, and with regard to the divided areas, sets the reduction scale factors gradually smaller as the divided areas become more distant from the first area.

8. A navigation system as claimed in claim 2, wherein the map drawing unit:

divides the areas on both sides of the first area into plural areas, and with regard to the divided areas, sets the reduction scale factors gradually smaller as the divided areas become more distant from the first area;

divides the area above the first area into plural areas, and with regard to the divided areas, sets the reduction scale factors gradually smaller as the divided areas become more distant from the first area; and

with regard to the areas obliquely above the first area, draws map information in the drawing memory with gradually decreasing scale factors in both the vertical and horizontal directions as the divided areas become more distant from the first area.

9. A navigation system as claimed in claim 2, wherein the map drawing unit draws map information in the drawing memory with a head-up display that includes a vehicle position in the first area and sets the travel direction of the vehicle upward on the image screen.

10. A navigation system as claimed in claim 2, wherein the map drawing unit draws the map information in the drawing memory with a north-up display that includes a vehicle position in the first area and sets the northern direction upward on the image screen.

11. A navigation system as claimed in claim 2, wherein the first area is drawn with an equal scale factor that is set by a user.

13. A method of displaying quasi-three-dimensional map information, as claimed in claim 12, wherein the first value and the second value are set to the same value.

14. A method of displaying quasi-three-dimensional map information, as claimed in claim 12, wherein the first value and the second value are set to different values.

15. A method of displaying quasi-three-dimensional map information, as claimed in claim 12, the method further comprising:

dividing the areas on the sides of the first area into plural areas, and with regard to the divided areas, setting the horizontal reduction scale factors gradually smaller as the divided areas become more distant from the first area; and

dividing the area above the lower area into plural areas, and with regard to the divided areas, setting the vertical reduction scale factors gradually smaller as the divided areas become more distant from the lower area.

16. A method of displaying quasi-three-dimensional map information, as claimed in claim 12, wherein the first area and the lower area are drawn with equal scale factors that are set by a user.

18. A method as claimed in claim 17, wherein the first scale factor is set by a user.

19. A method as claimed in claim 17, wherein the drawn map information is displayed in one of a head-up display, in which a vehicle position is included in the first area and a travel direction of the vehicle is upward, and a north-up display, in which a vehicle position is included in the first area and the northern direction in the displayed map information is upward.

20. A method as claimed in claim 17, wherein the first area is substantially centrally located with respect to at least one coordinate direction within the area to be displayed.

21. A method as claimed in claim 20, wherein the first area is substantially centrally located with respect to the X coordinate direction.

22. A method as claimed in claim 21, wherein the first area is located in the lower part of the area to be displayed.

23. A method as claimed in claim 17, wherein the second area is drawn, with respect to a first coordinate direction, with one or more scale factors smaller than a scale factor for the first area, and the second area is drawn, with respect to a second coordinate direction, with one or more scale factors smaller than a scale factor for the first area.

24. A method as claimed in claim 23, wherein the scale factors in the second area for each coordinate direction are set to be gradually smaller for areas within the second area that become more distant from the first area.

25. A method as claimed in claim 17, wherein the first scale factor is set to one.

12. A method of displaying quasi-three-dimensional map information, comprising:

reading map data corresponding to an area wider than an area required for displaying the map information with an equal scale factor;

drawing the map information, as to a horizontal reduction scale factor for a display screen, by setting a reduction scale factor for a first area to a first reference value, setting a reduction scale factor for areas on the sides of the first area to a first value smaller than the first reference value, and as to a vertical reduction scale factor for the display screen, by setting a reduction scale factor for a lower area to a second reference value, setting a reduction scale factor for an area above the lower area to a second value smaller than the second reference value; and

displaying the drawn map information on the display screen.

17. A method of displaying map information, comprising:

reading map data for an area to be displayed, where the map data are defined with respect to an X, Y coordinate system;

identifying a first area within the area to be displayed;

drawing map information based on the map data, where map information for the first area is drawn in accordance with a first scale factor in at least one of the coordinate directions, and map information for at least part of a second area within the area to be displayed that is outside the first area is drawn with a scale factor smaller than the first scale factor in the at least one coordinate direction; and

displaying the drawn map information for the area to be displayed.