Bezier curves for advanced driver assistance system applications

• US 8,725,474 B2
• Filed: 08/13/2009
• Issued: 05/13/2014
• Est. Priority Date: 10/01/2008
• Status: Active Grant

• Current Assignee: HERE Global B.V. (Nokia Corporation)
• Original Assignee: Navteq B.V.
• Inventors: Dorum, Ole Henry, Gnedin, Marianna
• Primary Examiner(s): Phan, Thai
• Assistant Examiner(s): LUU, CUONG V
• Application Number:
  US12/540,665
• Publication Number:
  US 20100082307A1
• Time in Patent Office: 1,734 Days
• Field of Search: 701/457, 701/450, 701/520, 703/5, 345/427
• US Class Current: 703/8
• CPC Class Codes: G01C 21/30 Map- or contour-matching
• CPC Class Codes: G01C 21/3819 Road shape data, e.g. outline of a route
• CPC Class Codes: G01C 21/3822 Road feature data, e.g. slope data
• CPC Class Codes: G01C 21/3867 Geometry of map features, e.g. shape points, polygons or for simplified maps

Abstract

A method and system for using Bezier curves in vehicle positioning and electronic horizon applications for providing data to advanced driver assistance systems (ADAS) applications are disclosed. The Bezier curves are obtained from B-splines. The obtained Bezier curves are subdivided in a manner that allows the vehicle positioning application to derive a polyline representation in real time. Using the Bezier and polyline geometry, the vehicle positioning application provides a vehicle position approximation to the ADAS applications. Using the Bezier curves, the electronic horizon application provides curvature, slope, and heading profiles to the ADAS applications.

Claims

1. A method for generating a curvature profile for use by a driver assistance application, comprising:

obtaining, by a processor, curvature information from B-spline road geometry representing at least one road segment;

converting, by the processor, the B-spline road geometry to Bezier curves to facilitate real time derivation of polyline representations thereof;

calculating, by the processor, arc length for the Bezier curves; and

publishing, by the processor, a curvature profile comprising a pair of values, a first value of which comprises the curvature information and a second value of which comprises the calculated arc length, the curvature profile being for use by at least one driver assistance application.

2. The method of claim 1, wherein obtaining curvature information includes

sampling the B-spline road geometry to obtain curvature and arc length;

graphing the obtained curvature and arc length;

calculating a polyline approximation of the graphed curvature and arc length; and

inserting knots in the B-spline road geometry corresponding to vertexes of the polyline approximation.

3. The method of claim 2, further comprising associating the inserted knots with a knot curvature flag.

4. The method of claim 3, wherein converting the B-spline road geometry to Bezier curves includes converting the knot curvature flag to a control point curvature flag.

9. The method of claim 1, wherein calculating of arc length for the Bezier curves further comprises using Gaussian quadrature to estimate arc length.

5. A method for generating a slope profile that can be used by a driver assistance application, comprising:

obtaining, by a processor, slope information from B-spline road geometry representing at least one road segment;

converting, by the processor, the B-spline road geometry to Bezier curves;

calculating, by the processor, arc length for the Bezier curves; and

publishing, by the processor, a slope profile comprising a pair of values, a first value of which comprises the slope information and a second value of which comprises the calculated arc length, the slope profile being for use by at least one driver assistance application.

6. The method of claim 5, wherein obtaining slope information includes

sampling the B-spline road geometry to obtain slope and arc length;

graphing the obtained slope and arc length;

calculating a polyline approximation of the graphed slope and arc length; and

inserting knots in the B-spline road geometry corresponding to vertexes of the polyline approximation.

7. The method of claim 6, further comprising associating the inserted knots with a knot slope flag.

8. The method of claim 7, wherein converting the B-spline road geometry to Bezier curves includes converting the knot slope flag to a control point slope flag.

10. The method of claim 5, wherein calculating of arc length for the Bezier curves further comprises using Gaussian quadrature to estimate arc length.