Method and apparatus for creating a clothoid road geometry
First Claim
Patent Images
1. A method comprising:
- converting a link geometry representative of a portion of a road network into a plurality of link splines comprising piecewise polynomial functions, wherein the link geometry comprises a plurality of links and is stored by a database, and wherein converting the link geometry into the plurality of link splines comprises defining a plurality of partially overlapping link chains with each link chain comprised of a plurality of links, converting each link chain into a respective link spline and aligning respective ends of the link splines corresponding to overlapping link chains;
converting the plurality of link splines into respective sequences of one or more clothoids based upon curvature profiles of the link splines, wherein converting the plurality of link splines into respective sequences of one or more clothoids comprises, for each link spline, determining a plurality of break-point locations along a respective link spline dependent upon a curvature profile of the link spline comprising an ordered array of [curvature κ
, arc length s] value pairs by identifying one or more zero-crossings to define one or more respective break-point locations, approximating a section between neighboring zero-sections with a polyline, and converting one or more sections of the respective link spline to respective clothoids; and
using the respective sequences of one or more clothoids by a map display or to support an advanced driver assistance system (ADAS).
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Abstract
A method, apparatus and computer program product are provided in order to create a clothoid road geometry. In the context of a method, a link geometry representative of a portion of a road network is converted into a plurality of link splines. The method also includes converting the plurality of link splines into respective sequences of one or more clothoids based upon curvature profiles of the link splines.
23 Citations
17 Claims
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1. A method comprising:
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converting a link geometry representative of a portion of a road network into a plurality of link splines comprising piecewise polynomial functions, wherein the link geometry comprises a plurality of links and is stored by a database, and wherein converting the link geometry into the plurality of link splines comprises defining a plurality of partially overlapping link chains with each link chain comprised of a plurality of links, converting each link chain into a respective link spline and aligning respective ends of the link splines corresponding to overlapping link chains; converting the plurality of link splines into respective sequences of one or more clothoids based upon curvature profiles of the link splines, wherein converting the plurality of link splines into respective sequences of one or more clothoids comprises, for each link spline, determining a plurality of break-point locations along a respective link spline dependent upon a curvature profile of the link spline comprising an ordered array of [curvature κ
, arc length s] value pairs by identifying one or more zero-crossings to define one or more respective break-point locations, approximating a section between neighboring zero-sections with a polyline, and converting one or more sections of the respective link spline to respective clothoids; andusing the respective sequences of one or more clothoids by a map display or to support an advanced driver assistance system (ADAS). - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus embodied by a map and positioning engine (MPE) or an advanced driver assistance system (ADAS), the apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the processor, cause the apparatus to at least:
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convert a link geometry representative of a portion of a road network into a plurality of link splines comprising piecewise polynomial functions, wherein the link geometry comprises a plurality of links and is stored by a database, and wherein the apparatus is caused to convert the link geometry into the plurality of link splines by defining a plurality of partially overlapping link chains with each link chain comprised of a plurality of links, converting each link chain into a respective link spline and aligning respective ends of the link splines corresponding to overlapping link chains; and convert the plurality of link splines into respective sequences of one or more clothoids based upon curvature profiles of the link splines, wherein the apparatus is caused to convert the plurality of link splines into respective sequences of one or more clothoids by, for each link spline, determining a plurality of break-point locations along a respective link spline dependent upon a curvature profile of the link spline comprising an ordered array of [curvature κ
, arc length s] value pairs by identifying one or more zero-crossings to define one or more respective break-point locations, approximating a section between neighboring zero-sections with a polyline, and converting one or more sections of the respective link spline to respective clothoids. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A computer program product embodied by a map and positioning engine (MPE) or an advanced driver assistance system (ADAS), the computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program code portions stored therein, the computer-executable program code portions comprising program code instructions configured to:
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convert a link geometry representative of a portion of a road network into a plurality of link splines comprising piecewise polynomial functions, wherein the link geometry comprises a plurality of links and is stored by a database, and wherein the link geometry is converted into the plurality of link splines by defining a plurality of partially overlapping link chains with each link chain comprised of a plurality of links, converting each link chain into a respective link spline and aligning respective ends of the link splines corresponding to overlapping link chains; and convert the plurality of link splines into respective sequences of one or more clothoids based upon curvature profiles of the link splines, wherein the plurality of link splines are converted into respective sequences of one or more clothoids by, for each link spline, determining a plurality of break-point locations along a respective link spline dependent upon a curvature profile of the link spline comprising an ordered array of [curvature κ
, arc length s] value pairs by identifying one or more zero-crossings to define one or more respective break-point locations, approximating a section between neighboring zero-sections with a polyline, and converting one or more sections of the respective link spline to respective clothoids. - View Dependent Claims (14, 15, 16, 17)
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Specification