A New Simplification Approach Based on the Oblique-Dividing-Curve Method for Contour Lines

Abstract

As one of the key operators of automated map generalization, algorithms for the line simplification have been widely researched in the past decades. Although many of the currently available algorithms have revealed satisfactory simplification performances with certain data types and selected test areas, it still remains a challenging task to solve the problems of (a) how to properly divide a cartographic line when it is too long to be dealt with directly; and (b) how to make adaptable parameterizations for various geo-data in different areas. In order to solve these two problems, a new line-simplification approach based on the Oblique-Dividing-Curve (ODC) method has been proposed in this paper. In this proposed model, one cartographic line is divided into a series of monotonic curves by the ODC method. Then, the curves are categorized into different groups according to their shapes, sizes and other geometric characteristics. The curves in different groups will trigger different strategies as well as the associated criteria for line simplification. Whenever a curve is simplified, the whole simplified cartographic line will be re-divided and the simplification process restarts again, i.e., the proposed simplification approach is iteratively operated until the final simplification result is achieved. Experiment evidence demonstrates that the proposed approach is able to handle the holistic bend-trend of the whole cartographic line during the simplification process and thereby provides considerably improved simplification performance with respect to maintaining the essential shape/salient characteristics and keeping the topological consistency. Moreover, the produced simplification results are not sensitive to the parameterizations of the proposed approach.

Shape Similarity Assessment Method for Coastline Generalization

“…However, the relationship among bends obtained by this method is simple linear adjacency, which means the multi-scale feature of linear feature shape is neglected. Later, the method based on inter-visibility was presented [58]. Until now, the most representative method is the one based on Constrained Delaunay Triangulation (CDT) [54].…”

Base Point Split Algorithm for Generating Polygon Skeleton Lines on the Example of Lakes

“…Zigzag effects are minimal when the polygon has uniform width, and they are more extensive in polygons with varied width (Figure 27c and Figure 28a). Various line simplification methods are described in the literature [23][24][25][26][27]. An alternative smoothing method, which is a variant of the moving average approach, was proposed in this study.…”

A Global Continuous Multi-Scale Terrain Contour Simplification Method Based on the Level Set

“…Various contour simplification methods have been proposed over the past few decades. These methods can mainly be divided into (1) reduction in point set [10][11][12][13][14][15], (2) bending simplification [8,[16][17][18][19][20], and (3) scale-driven simplification [9,[21][22][23][24].…”