WebGIS中多维空间数据多尺度表达索引结构*

针对现有数据结构无法支持WebGIS中多维空间数据的多尺度表达，提出了一种改进的数据结构：a)主树由金字塔层级结构规则分割的区域四叉树索引结构变形而来;b)具有支持多维数据的重叠子树结构;c)利用树的深度反映空间分辨率的变化;d)主树的所有节点均为空间对象载体，子树的节点为多维数据单元。分析了该索引产生的必要性，对该索引结构进行描述，并着重对该索引结构中的数据生成算法、多维数据支持和搜索过程进行了讨论。针对相同数据源，使用本结构与图层表达法进行对比实验，结果表明，该索引方法能对WebGIS中海量多维空间数

Index structure for multi-scale representation of multi-dimensional spatial data in WebGIS

To solve the problem that existing data structure cannot support the multiscale representation of multi-dimensional spatial data in WebGIS, this paper put forward a modified data structure: a) getting the main tree from the deformation of the index structure of region quadtree partitioned on the basis of the rule of pyramid structure; b) possessing the sub-tree structure supporting the overlap of multi-dimensional spatial data; c)reflecting the changes in spatial resolution using the depth of the tree; d)all the nodes of the tree are the container of spatial objects. Analyzed the necessity of generating the index which was described. The algorithm for data generation of index structure, discussed the support to the multi-dimensional data and the query process. For the same data source, provided some comparative experiments using this structure and layer. The result shows that this index method can represent and search massive multi-dimensional spatial data effectively in WebGIS. The structure has been used in Shanghai multi-dimensional WebGIS system.