河网自动综合中Delaunay三角的应用

在地图数据处理和GIS分析应用中,河网自动综合是制图综合的一个重要组成部分,其中涉及到从双线河向单线河转化的过程及河间距的研究。本文利用Delaunay三角网中的三角形的边连接具有的空间邻近性特点,介绍了用Delaunay三角网结构的骨架线来提取双线河流中轴线及研究河间距量算的方法。

The Application of Delaunay Triangulation in River Net Automatic Generalization

Map is one of the important means of space information spread.The quantity of space information not only is big and complicated, but also increases steadily.Therefore, to reflect the big and complicated space information on limited map,cartographers have to reflect the main and essential aspects and throw away the subordinate aspects , for the legibility of map.This process is referred to as map generalization.In the process of automatic map generalization, river generalization is an important constitutional part of map data handling.Along with map scale variations , some double line rivers on the large scale maps have to be expressed by using single line rivers on the small scale maps.That is to say that in the automatic river generalization there exists a process of converting a double line river into a single line river.That is to bring up the inside stalk line from the double line river.Moreover, while establishing the river system's tree construction, the simplification from the double line river to the single line river will make it more convenient to establish the river construction relationship.The skeleton line for the construction of Delaunay triangulation net has one dimension characteristic which is brought up from two dimensional space.It has the nature of equally divided part of district.Therefore it is appropriate to bring up the stalk line inside double line river by establishing the skeleton line of Delaunay triangulation.In the automatic generalization process of river system, along with the contracting of scale, it is important to transfer attention to the characteristic of whole river net.Among them the main point is to keep the relative density and difference of river net.So, it is necessary to know the distance between near by rivers.But it is not easy to know the distance.Because of the complexity of the river curve shape the measuring calculation of the distance is difficulty and the results vary from person to person.The paper also researches the method for measuring calculation of the distance between nearby rivers by using the Delaunay triangulation.