地图信息的拓扑检索
Topological Retrieval of Map Information
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摘要: 从本质上看,地图数据处理是一种拓扑变换,即在连续变形(处理)中要保持数据中所内函的不变性(结构特征)。当数据处理系统由拓扑关系所充实与制导时,其智能程度就大为增强,可使其由线性处理演变为非线性处理(关联处理)。根据物体间邻接与关联的强烈程度,可把拓扑关系分为两大类:确定型与模糊型。前者原则上用显式表示,后者则宜用隐式表示。两种表示方式作了简要的对比,並强调隐式结构有着经济性与灵活性的主要优点。同时还强调指出,在建库过程中拓扑信息的人工输入应趋于最少。地理信息的检索可分为两类:常规检索与拓扑检索。对于前者,检索的依据是物体本身的标志,如定性检索与定位检索;而对于后者,检索的依据是物体集合之间的空间关系(如邻接关系、关联关系和包含关系)。实现以常规检索为基础的间接拓扑检索,其实质就是用程序的手段把隐含在数据结构中的所求的拓扑关系借助于两个倒排文件(标题索引与栅格索引)予以显式化。文末介绍了三种典型的间接拓扑检索:基于点集合的拓扑检索,基于线集合的拓扑检索和基于面集合的拓扑检索。Abstract: In essence, map data processing can be considered as a topological transformation, i.e.under continuous transformation (data processing) an invariance (structure feature) inherent in the data should be preserved. When a data processing system is enriched with topological relations and controlled by the later, the system's intelligence will be strengthened considerably. This causes the linear property in previous data processing to become non-linear (correlated). In accordance with the strength of the adjacency and incidence between the objects the topological relations can be classified into two major categories, determinative and fuzzy types. In principle, the former should be represented explicitly, while the later implicitly. In this paper a brief comparision between the two representations is made. It is emphasized that the implicit structure has some advantages, economy and flexibility. This paper notes that the quantity of topological information input manually should tend to minimum. The retrieval of geo-information can be classified into 2 groups, traditional and topological retrieval. The former deals with the object attributes only, e.g. the property oriented retrieval and location oriented one, the later is based on the spatial relationships (e.g.adjacency, incidence and inclusion) between the object sets. The essence of the indirect topological retrieval based on traditional one is that the explicitation of topological relations implicited in the data structure is realized through two inverted files called header index (attribute-oriented) and location index (raster or mesh oriented). At the end of this paper 3 typical means for indirect topological retrieval are introduced. Topological retrieval based on point set; Topological retrieval based on line set; Topological retrieval based on area set.