Patent ID: 8126934

Claim:
A computing method of updating a database that comprises a geometric representation of a train track and a plurality of offsets corresponding to the geo-locations of features on the train track, the method comprising: converting, by a data-processing system, geo-locations of a first set of points on the train track from latitude/longitude/altitude coordinates to three-dimensional Earth-Centered Earth-Fixed Cartesian coordinates; generating, by the data-processing system, based on the three-dimensional coordinates of the first set of points, a piecewise polynomial spline that is defined in terms of a proper subset S of the first set of points; removing from the database entries corresponding to a second set of points on the train track; and storing, by the database, new entries corresponding to the subset S, wherein each of the new entries comprises: (i) three-dimensional Earth-Centered Earth-Fixed Cartesian coordinates, (ii) an estimate of the heading of the train track, (iii) an estimate of the grade of the train track, and (iv) an estimate of the curvature of the train track; wherein the geometric representation comprises a piecewise polynomial spline.