Extraction of Topographic Structure Lines from Digital Elevation Model Data

Abstract

Topographic structure lines, including ridge lines and valley lines, delineate the most prominent skeleton structures of the land forms. Extraction of topographic structure lines plays an important role in various fields where topographic features are used in spatial analysis such as hydrological applications, military applications, hazard prediction, hiking and mountain climbing, relief representation and delineation. Traditionally, these structure lines were manually interpreted from hardcopy topographic maps which indicate continuous topographic surface by contours. With the aid of digitizing devices, topographic features on the topographic maps were digitized and converted into a digital terrain model (DTM) that contains elevation information and some explicit coding of surface characteristics such as peaks, pits, break lines, boundaries, etc. Many forms of DTM have been used to describe the terrain surface digitally, including digital contour model (DCM) with form lines of equal elevation, digital elevation model (DEM) in a two-dimensional regular-spaced grid of sampled elevations, or triangulated irregular network (TIN) of irregularly distributed topographic features. Among them, DEMs in gridded matrix form can be easily acquired by different approaches and are ubiquitous in various applications, including gradient/slope/aspect analysis in geographical information systems (GIS), terrain synthesis, detection of drainage networks, extraction of skeleton lines or ridge and valley lines [1-9].