Multi-criterion methods to extract topographic feature lines from contours on different topographic gradients

Abstract

The existing methods of the automatic extraction of topographic feature lines from terrain representation either have too high sensitivity to terrain noise or lose significant branches. In this study, we present new multi-criterion methods to extract topographic feature lines from contours on different topographic gradients according to the negative or positive signs of the curvature and neighboring feature points on the contours, the hierarchical structure of these feature points, and the spatial relationships between topographic feature lines and contours. First, the digitization directions of source contours were automatically detected and adjusted (when necessary) to establish the spatial relationships among the contours before we extract and group the feature points in the terrain. Second, we determine the ‘mainstreams’ and ‘tributaries’ of the topological structure trees according to the relationships among the previously identified feature point groups. Finally, a key aspect of our paper is the proposition of multi-criterion methods to extract topographic feature lines. Compared with the regular square grids (RSG)-based and Voronoi skeleton-based methods, the proposed methods can extract topographic feature lines with higher accuracy, better continuity, lower spatial logical conflicts between topographic feature lines and contours.