基于格网索引的GIS矢量数据拓扑重建研究

GIS中对原始矢量数据进行拓扑分析和重建是对其进行存储和使用的前提。引入包括规则格网和四叉树格网在内的索引结构,将全局的矢量拓扑分析转化为单个格网范围内足够少的矢量线段求交过程,减少了运算的复杂度;并用一种重组算法实现将原始矢量数据转化为符合“逢交必断”标准的矢量数据。试验表明,该算法适合海量和高散乱度的矢量数据。

A Study on Topological Reconstruction of GIS Vector Data Based on Grid Index

Vector data plays an important role in geographical information system.But the topology of vector data should be constructed correctly before use and storage.No intersection should remain after reconstruction,or results of the succeeding process are unpredictable.One difficulty in reconstruction is that the inputted data can be of arbitrary forms,bringing about numerous intersection points.It is generally time-consuming to find out all intersection points correctly.In this paper,a grid index made of regular grid or quad-tree grid was presented.The index by subdividing 2D space into some subregions was created,and each of the subregions contains fewer polylines.Based on the index,the problem of analyzing global topological relationship can be transformed into calculating intersections of very few segments within a single grid,which saves operations greatly.Each grid is processed in this way respectively.Finally,a reconstruction algorithm is used to organize original vector data into standard data,which must contain nodes where no intersections exist.The experimental result indicates that the algorithm is specially suitable for mass data and highly irregular data.