Three-dimensionally consistent contour-based network rendered from digital terrain model data

Abstract

A common geomorphometric object in geospatial analysis is the contour-based network (CBN). Unlike grid- and patch-based networks, CBN partitions an entire terrain surface vertically. Traditional methods connect streamline segments with consecutive contours according to orthogonality or minimum-distance measure. This causes three-dimensional inconsistency (not all straight segments intersect orthogonally with a contour). Therefore, segments deviate from the exact streamline. The steepest descent methodology seems applicable; however, it was designed for optimization rather than tracking. A trajectory would oscillate at narrow hills and valleys, and tracing terminates once a convergence criterion follows. This occurs irrespective of proximity to an exact stationary point, but no method for continuation exists. Thus, the author devised a framework for a three-dimensionally consistent CBN. The curvature vector and tolerance help achieve good reproductivity, storage efficiency, and adjustable precision. The proposed method advances inward of the exact curve and continues moving over stationary points, adhering to the original terrain surface. A complete CBN is composed via gleaning the streamline curves by including contours identified by another method. The resulting object emanates smooth curves along with three-dimensional consistency. A demonstrative experiment is conducted using a lower-resolution digital terrain model dataset; the results highlight the significance of the devised framework.