METHOD OF APPLYING CLOTHOID CURVE VALUES TO ROADWAYS IN A GEOGRAPHIC DATA INFORMATION SYSTEM
First Claim
1. A method for applying clothoid curve values to roadways in a geographic data information system, comprising:
- selecting database segments in the geographic data information system, wherein the database segments describe roadways;
determining segment chains from the selected database segments, wherein determining the segment chains comprises;
identifying a plurality of at grade junctions of the selected segments and all dead ends of the selected segments as important locations; and
finding each geographic chain of segments that traverse from any such important location, and touch no other such important location, until reaching the same or other such important location,preparing the segment chains for transition to curvature space;
transitioning to a curvature function in the curvature space, by computing heading change at points along the segment chains, resulting in a transformation of the segment chains into clothoids;
smoothing the curvature function;
fitting the smoothed curvature function with a more generalized form which remains within a selected tolerance of the smoothed curvature function; and
storing parametric values of the smoothed curvature function for the segment chains in the geographic data information system.
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Abstract
Embodiments of the invention are methods for applying clothoid curve values to roadways in a geographic data information system. One embodiment is a method, comprising: selecting database segments in the geographic data information system, wherein the database segments describe roadways; determining segment chains from the selected database segments; preparing the segment chains for transition to curvature space; transitioning to a curvature function in the curvature space, by computing heading change at points along the segment chain, resulting in a transformation of the segment chains into clothoids; smoothing the curvature function; fitting the smoothed curvature function with a more generalized form which remains within a selected tolerance of the smoothed curvature function; and storing identified segments of straight lines, transition zones, and segments of constant curvature in the geographic data information system.
24 Citations
11 Claims
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1. A method for applying clothoid curve values to roadways in a geographic data information system, comprising:
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selecting database segments in the geographic data information system, wherein the database segments describe roadways; determining segment chains from the selected database segments, wherein determining the segment chains comprises; identifying a plurality of at grade junctions of the selected segments and all dead ends of the selected segments as important locations; and finding each geographic chain of segments that traverse from any such important location, and touch no other such important location, until reaching the same or other such important location, preparing the segment chains for transition to curvature space; transitioning to a curvature function in the curvature space, by computing heading change at points along the segment chains, resulting in a transformation of the segment chains into clothoids; smoothing the curvature function; fitting the smoothed curvature function with a more generalized form which remains within a selected tolerance of the smoothed curvature function; and storing parametric values of the smoothed curvature function for the segment chains in the geographic data information system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification