The automated road network schematization by using straight and curved lines

Pao Yue-kong Library Electronic Theses Database

The automated road network schematization by using straight and curved lines

 

Author: Li, Chen
Title: The automated road network schematization by using straight and curved lines
Degree: M.Sc.
Year: 2014
Subject: Roads -- Maps.
Visual programming (Computer science)
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Construction and Environment
Pages: xiii, 82 pages : illustrations (some color) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2759113
URI: http://theses.lib.polyu.edu.hk/handle/200/7569
Abstract: A schematic map is a diagrammatic representation based on linear abstractions of networks. The advent of schematic assists people in swift searching for the required travel route. With the highly-developed computer technology, it promotes the schematization to transform from traditional manufacturing to auto-establishment by computer. However, the lines may not be displayed in the computer as correctly as it was in the traditional way. Previous work has focused on the straight-line style where edges are drawn horizontally, vertically, or diagonally. The methods above are mainly based on lines. In one hand, the regular lines effectively demonstrate important information of the map when there are few lines. In the other hand, it fails to provide the users the simple, prompt, specific information when there are too many lines. Though the newly-released curved schematization makes up for the aesthetic and recognition, the problems still remain unsolved since the method above is only targeted on the shape of the elements which is not suitable for other data (like road network). In reality, many city roads are abounded in curvature road or with long main road, in this sense, schematic map which dig deep in the shapes of the roads above is bound to exhibit location for people and build them with good heart cognition. Therefore, in this paper, a combination of the curves and the lines will be used in producing automated stroke-based road network schematic map. The strokes defined by road names are seen as the basic unit and are divided into curve part and line part. After ranking strokes, adjustment of strokes direction, length and displacement as well as the topological examination will be done to make the terminal schematic map while some of its curves strokes will be fitted by cubic Bézier curve. There will be specific details about it later in the paper. Real road network data are in use while examples are shown to testify the results. It is discovered that the road network with the combination of the curves and lines is easier for people to remember than those with only lines. Meanwhile, the consequence is more abstract while maintaining the outline and the shape of the data. The first chapter of this paper gives an introduction of the schematic map about its background, related works, motivations as well as the objectives. The steps involve in generation of the schematic map, CPSA and cubic Bézier curve fitting method will in chapter 2. In chapter 3, the generalization of angle and length, and method of topological maintenance will be described. In chapter 4, real data are used to evaluate the consequence and the relationship between the threshold and results will be discussed while the conclusion and future work are in the final chapter.

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