Skeleton line extraction for areal hydrographic elements considering spatial and hierarchical relationships

Abstract

This study focuses on a skeleton line extraction algorithm of areal hydrographic elements for cartographic generalization. The requirements of skeleton line extraction for areal hydrographic elements were first analysed and a new automatic extraction algorithm that considered spatial and hierarchical relationships was proposed to meet these requirements. A graph with structured areal hydrographic elements was subsequently presented, and the graph pruning operation was conducted based on the spatial relationship and pruning length threshold. The skeleton line connection of the traditional unconstrained edge midpoint algorithm was improved by the guidance of spatial and hierarchical relationships. Finally, the proposed method was used to extract skeleton lines from 1:250,000 hydrographic elements, and compared with other algorithms. The experiments demonstrate that the skeleton lines extracted by the proposed method have certain advantages in natural continuity, hierarchy, and topological consistency; the results are closer to those of manual extraction and avoiding the subsequent optimization process.