Extraction of Terrain Feature Lines from Elevation Contours Using a Directed Adjacent Relation Tree

Chengming Li,Xiaoli Liu,Peipei Guo,Pengda Wu

doi:10.3390/ijgi7050163

Abstract

The extraction of terrain feature lines is an important yet challenging problem in the processing and usage of contour lines. Most research has focused on identifying terrain feature points by using methods such as the Douglas–Peucker (D–P) algorithm and on determining contour adjacent relations for closed contour lines by using methods such as Delaunay triangulation and its dual Voronoi diagram, with few attempts made to address open contour lines and identify the direction of contour lines. Here, we propose a novel method for terrain feature line extraction based on adjacent relation trees. First, a contour adjacent relation tree is constructed. The tree is used to determine the directions of closed and open contour lines and thereby form a “directed adjacent relation tree” (DART). Terrain feature points are then extracted using the classic D–P algorithm, followed by the identification and connection of valley and ridge points via the aforementioned DART. Finally, integrity compensation for terrain feature lines is performed based on a slope extension algorithm. The effectiveness and accuracy of this method is verified by experimental results obtained from 1:10,000 topographic map data.

Highlights

Terrain feature lines describe the skeletal structure of a terrain and they are the basis for a variety of important applications, including terrain analysis [1], contour generalization [2,3,4], and hydrologic analysis [5]
One of the most common approaches in these studies is to begin by detecting feature points according to terrain geometry and to construct terrain feature lines by connecting strongly hierarchical and symmetrical feature points that lie on adjacent contour lines [5,9]
Methods of contour-based terrain feature line extraction depend on two fundamental processes: the detection of contour adjacent relations and the determination of contour directions for closed and open contours within a map

Summary

Introduction

Terrain feature lines describe the skeletal structure of a terrain and they are the basis for a variety of important applications, including terrain analysis [1], contour generalization [2,3,4], and hydrologic analysis [5]. The automatic extraction of terrain feature lines has become a hot topic in topographic research [6,7,8], with researchers all over the world conducting many related studies in recent years. Methods of contour-based terrain feature line extraction depend on two fundamental processes: the detection of contour adjacent relations and the determination of contour directions for closed and open contours within a map. The former ensures that we can reduce the search range when connecting feature points, whereas the latter ensures that ridge and valley points can be accurately distinguished

Objectives

Methods

Conclusion