S PLIT A REA : an algorithm for weighted splitting of faces in the context of a planar partition

et al. 2019

Transactions in GIS

The extraction of partition lines for long and narrow patches (LN patches) is an important yet difficult problem in the generalization of thematic data. When current methods are used to process polygons with irregular shapes or complex branch convergence zones, the extracted line structural features tend to be inaccurate and topologically erroneous. In this article, we propose an improved partition lines extraction algorithm of constrained Delaunay triangulation to counter these issues. The proposed method aims to maintain consistency between the extracted line structure characteristics and the actual object structure, especially for complex branch convergence zones. First, we describe three types of aggregation patterns (Type A, B, and C aggregation zones) that occur in partition line extractions for LN patches of complex branch convergence zones using Delaunay triangulation. Then, a partition line extraction algorithm that accounts for the direction between the edges of triangles and the distance of nodes in aggregation zones is proposed. Finally, we test our method for a dataset relating to Guizhou Province, China. Compared with the current method that uses quantitative indicators and visualization, the results indicate that our method not only has applicability for simple situations but also is superior for preserving structural features of complex branch convergence zones.

Section: Related Workmentioning

confidence: 99%

Section: The Principles Of Partition Line Extraction Via Constrainementioning

confidence: 99%

A method for the extraction of partition lines from long and narrow patches that account for structural features

Dai

et al. 2019

Transactions in GIS

“…Jiang et al [17] presented a dot symbol filling method for the complex land-type areas based on a simple polygonal segmentation. The basic idea of the method is constructing constrained Delaunay triangulation [18] for complex areas, and a simplex segmentation is performed, such that the narrow area and the two-dimensional extension area of a polygon can be distinguished according to the geometric features of the polygon. Then, various strategies are designed to fill the dot symbols according to the characteristics of different parts of the polygon.…”

Section: Existing Dot Symbols Filling Methodsmentioning

confidence: 99%

Dot Symbol Auto-Filling Method for Complex Areas Considering Shape Features

2019

IJGI

Filling dot maps with a regular pattern is a key step in visual representation of land use data. The traditional methods cannot adapt well to shape features of complex areas, leading to an unreasonable symbol arrangement in the inner region and area boundaries during symbol filling. For this reason, a dot symbol auto-filling method of complex areas considering shape features is proposed in this paper. First, based on the constrained Delaunay triangulation, the internal structure of a complex area is divided into three simple filling areas denoted tile type, narrow type, and point type. Next, according to the geometric shape features, these three type areas are filled with plane, line, and point level of symbols respectively. Finally, the dot symbols near to boundaries are adjusted on the basis of the boundary constraint to optimize the symbol-filling effect. Based on the national data of a region in Guizhou Province, the method proposed in this paper is compared to the traditional symbol filling methods for validation. The experimental results show that the proposed method improves the dot symbol sufficiency of complex areas, and the edge of dot symbol group closely adhere to the boundary and conform to the extension characteristics of boundary without creating spatial conflicts such as spatial overlap, the filling result can better reflect the shape features of the areas.

“…It is obvious that the split lines at the single nodes in these figures do not satisfy the aforementioned constraint imposed by the connecting nodes of adjacent polygon boundaries, thus the split lines need topology correction. The most common method of split line topology correction is the closest point method [26] and the triangulation supplement method [27]. However, these two methods have less consideration for the extension nature of boundary lines.…”

Section: Topology Correction For Nodes With Degreementioning

confidence: 99%

Improved Jitter Elimination and Topology Correction Method for the Split Line of Narrow and Long Patches

et al. 2018

IJGI

Extracting the split line of narrow and long patches is important for the generalization of land-use thematic data. There are two commonly used methods for extracting the split lines: One is based on Delaunay triangulation and the other is based on straight skeletons. However, it is difficult for the straight skeleton method to preserve geometric structure and topological consistency with the original data when dealing with polygons that have irregularity and complexity of junctions. Therefore, we propose an improved jitter elimination and topology correction method for split lines based on a constrained Delaunay triangulation. First, a split line adjustment algorithm based on the geometric structure of the polygon is proposed to eliminate the jitters. Second, a split line topology correction algorithm is proposed for nodes with degree 1 or degree 2, considering the boundary topological constraint. The reliability of the proposed method is verified by comparing it with the straight skeleton method using sample data and the superiority of the proposed method is verified by using actual data from China’s geographical conditions census in the Guizhou province.