Bowing coefficient representation of curvature of geographic features

• US 6,681,177 B2
• Filed: 01/30/2001
• Issued: 01/20/2004
• Est. Priority Date: 01/30/2001
• Status: Expired due to Term

• Current Assignee: HERE Global B.V. (HERE Holding Corporation)
• Original Assignee: Navteq North America LLC (HERE Holding Corporation)
• Inventors: Joshi, Rajashri
• Primary Examiner(s): Cuchlinski, Jr., William A
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/772,587
• Publication Number:
  US 20020128752A1
• Time in Patent Office: 1,085 Days
• Field of Search: 701/208, 701/207, 701/25, 701/26, 701/1, 340/988, 702/157, 702/155
• US Class Current: 701/208
• CPC Class Codes: G01C 21/3819 Road shape data, e.g. outline of a route
• CPC Class Codes: G09B 29/003 Maps

Abstract

The degree to which a linearly extending feature, such as a road, curves is indicated using a bowing coefficient. The bowing coefficient at a given location along a linearly extending feature is determined by comparing the distance along the feature between two points on either side of the given location (or an approximation of the distance) to a straight-line distance between these same two points. Bowing coefficient data can be used by various vehicle systems that require information about the curvature of linearly extending features, such as roads upon which the vehicle is traveling.

Claims

1. A method of representing road geometry comprising:

at selected locations along a road, determining a bowing coefficient, wherein the bowing coefficient at each of said selected locations corresponds to a comparison between an approximation of a distance along the road between a first point and a second point on the road on either side of the selected location and a straight-line distance between the first point and the second point; and

using the bowing coefficient as an indication of curvature of said road between the first point and the second point.

2. The method of claim 1 further comprising:

using said indication of curvature to adjust a speed of a vehicle.

3. The method of claim 1 further comprising:

storing said indication of curvature in a geographic database.

4. The method of claim 1 wherein said comparison is performed using shape point data that represent geographic coordinates at locations along the roads.

5. The method of claim 1 wherein said comparison is performed by an application in a vehicle.

6. The method of claim 1 further comprising:

storing data indicating said bowing coefficient in a geographic database that represents said road.

7. A geographic database formed according to the process of claim 1.

8. A method of operating a vehicle along roads comprising:

with a software application in said vehicle, accessing a database containing data that represent said roads;

determining a location of said vehicle with respect to the roads as represented by said database; and

using data that indicate a bowing coefficient at each of a plurality of locations along said roads to adjust operation of said vehicle, wherein a speed at which said vehicle is moving is reduced as said vehicle approaches a portion of said roads at which said bowing coefficient is relatively higher.

9. A method of operating a vehicle along roads comprising:

with a software application in said vehicle, accessing a database containing data that represent said roads;

determining a location of said vehicle with respect to the roads as represented by said database; and

using data that indicate a bowing coefficient at each of a plurality of locations along said roads to adjust operation of said vehicle, wherein a speed at which said vehicle is moving is increased as said vehicle approaches a portion of said roads at which said bowing coefficient is relatively lower.

10. A method of operating a vehicle along roads comprising:

relating a position of said vehicle on a road to a data representation of the road contained in a geographic database,

wherein the data representation of the road includes an indication of curvature at locations along the road, and

wherein the indication of curvature includes a comparison between an arc length between points along the road and a chord length between the points; and

adjusting operation of the vehicle based on the indication of curvature corresponding to said position of said vehicle.

11. The method of claim 10 wherein said comparison is performed using data contained in a geographic database located in said vehicle.