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

Elżbieta Lewandowicz,Paweł Flisek

doi:10.3390/ijgi9110680

Abstract

This article presents the Base Point Split (BPSplit) algorithm to generate a complex polygon skeleton based on sets of vector data describing lakes and rivers. A key feature of the BPSplit algorithm is that it is dependent on base points representing the source or mouth of a river or a stream. The input values of base points determine the shape of the resulting skeleton of complex polygons. Various skeletons can be generated with the use of different base points. Base points are applied to divide complex polygon boundaries into segments. Segmentation supports the selection of triangulated irregular network (TIN) edges inside complex polygons. The midpoints of the selected TIN edges constitute a basis for generating a skeleton. The algorithm handles complex polygons with numerous holes, and it accounts for all holes. This article proposes a method for modifying a complex skeleton with numerous holes. In the discussed approach, skeleton edges that do not meet the preset criteria (e.g., that the skeleton is to be located between holes in the center of the polygon) are automatically removed. An algorithm for smoothing zigzag lines was proposed.

Highlights

Automated solutions for processing vector data relating to surface water bodies and rivers have many practical applications, and they can be used to generate a skeleton of a hydrographic network
Different types of triangles are identified in polygons that are generated with the use of methods based on triangulated irregular networks (TIN) [7,10,20]
In the solution proposed by Meijets et al [10], a skeleton is generated based on all TIN edges, and it is modified in successive steps to deliver the required functionality

Summary

Introduction

Automated solutions for processing vector data relating to surface water bodies and rivers have many practical applications, and they can be used to generate a skeleton of a hydrographic network. This is accomplished with the use of generation algorithms. Different types of triangles are identified in polygons that are generated with the use of methods based on triangulated irregular networks (TIN) [7,10,20]. The second research task was to investigate the ability of the proposed algorithm to generate skeletons for polygons with numerous holes (islands on water bodies), where the skeleton’s location between islands was modified automatically based on the preset criteria. The present study was conducted with the use of programming tools in ArcGIS (ESRI) software [21,22] and the algorithms developed by the authors in Python

The First Research Task—Characterization of the Bpsplit Algorithm

Skeleton Adjustment with the BPSplit Algorithm

Summary of the BPSplit Algorithm

Conclusions