A Novel Geodetic Engineering Method for Accurate and Automated Road/Railway Centerline Geometry Extraction Based on the Bearing Diagram and Fractal Behavior

This paper describes a novel approach for extracting the centerline geometry of road/railway alignments in the form of traditional design elements (i.e., straight lines, circle arcs, and clothoids). As opposed to previous research, the proposed method attempts a completely general and a fully automated solution to the problem in a rigorous mathematical manner. Centerline locations originate in a ground-based mobile mapping system (e.g., global navigation satellite system/inertial navigation system vehicle trajectory or kinematic laser scanning profiles of the road/railway corridor). The core of the algorithm resides on the use, manipulation, and suitable reformulations of the bearing diagram of the centerline locations and its first- and second-order derivatives. To ensure highly accurate and consistent results, the algorithm practices a series of specifically designed/dynamically tuned filters that fully adhere to the fractal properties of the centerline location data. Extended test runs were undertaken to validate the correctness of the mathematical model and the feasibility of the algorithms and associated software. In this paper, test results using a simulated and a real (based on a multisensor geodetic survey) subset of a railway track data are discussed.