The Study Of Spatial Operation Based On Topological Map Model

The spatial data model is an abstract and formal description of the geospatial space entities and their correlation in a conceptual way.It‘s an abstract and formal description of geographical space.The spatial data model provides basic methods for describing spatial data,organizing and designing spatial database.Also it is the foundation and core of geographic information system.Spatial relations are an important part of the spatial data model,which describes the existence of spatial relationships between spatial entities.Topological relations are the most important basic relationships in spatial relations,and describe a relationship that spatial entities remain invariant under topological transformations.Spatial operation is based on the location and shape of spatial entities,computes the topological relations between spatial entities and generates new spatial entities.Spatial operation is the basis for spatial data processing and spatial analysis of geographic information systems.The relationship between topological and spatial operation is closely related to spatial data model.The advantages and disadvantages of spatial data model determine the technical ability and application ability of geographic information system.Therefore,it is of great theoretical and practical significance to study the concrete and practical spatial data model.The topological map model is a spatial data model that can express the spatial characteristics of the entity,the spatial relationship between the entities,the attribute of the entity and the spatial representation of the symbolic representation of the entity at the same time,.In this paper,the spatial operation model based on the topology map model is studied deeply.The main contents and achievements are as follows:1.The relationship among entities,geometric and symbol is studied.The topology map model is composed of entities,geometric,attribute,symbol and so on.The conceptual description of these concepts is discussed,and the linkage relation between entities,geometry and symbols is discussed.The operation of the entity will affect the geometry and symbols at the same time.The manipulation of the geometry will affect the position and shape of the entity without affecting the symbol.The manipulation of the symbol will affect the symbol expression of the entity without affecting the geometry.2.Propose a method for transforms the topology map model by topological processing.When using the topological map model to perform spatial computation;it needs to be transformed into a topological map model to express it,which can be realized by topology.When the entity is subjected to topology processing,the geometric objects of the entity insert the nodes in the intersection,contact,repetition,and adjacent positions,and merge or break down the nodes,and form a composite geometric object to express the position and shape of the original entity.3.Introduce the graph to describe the hierarchical relationship between geometric objects.The geometric objects of the topological map model have a complex relationship between nodes and basic geometric objects-composite geometric objects.This relation is the basis of topology analysis and geometry analysis.The paper uses graphs to describe the hierarchical relationships between geometric objects.By abstracting geometric objects into vertices and geometric objects the relationship is abstracted into the edges in the graph,and the geometric relationships between the geometric objects are established.4.Proposed a method for computing topological relations by using the combination of graph operations and computational geometry.Based on the expression of geometric relation graph,this paper proposes the method of graph operation and geometric calculation to deduce the specific topological relations among entities by analyzing the structure of points and line vertices and the combination of points and lines.And the criteria for judging the various topological relations between points,line and surface entities in DE-9IM model are given.5.Proposed a method for spatial geometry operation by update geometric relation graph.Based on the analysis of the result of the graph and the position analysis of the geometric object,the geometric relation graph is updated,and the result is expressed by the geometric relation graph.The geometric relation graph is designed according to the geometric operation type of different spatial geometric operations.In the method of geometric reconstruction,the spatial geometric operation between entities is realized.6.Design and implement a prototype.In this paper,the prototype system is designed and constructed,and the validity and correctness of the theory and method proposed in this paper are verified by topological processing and geometric relation experiment,topological relation operation experiment and spatial geometry experiment.