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The Key Techniques Of Spatial Database Based On Regularly Spatial Discrete Domains Objects

Posted on:2003-11-17Degree:DoctorType:Dissertation
Country:ChinaCandidate:T W ZhuFull Text:PDF
GTID:1118360092998844Subject:Information and Communication Engineering
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In this paper, the objects that we research are spatial geometry in three-dimensional Euclidean space. The definitions of spatial objects conform to OpenGIS specification. OpenGIS specification is a non-compellable specification, which is established by the Open GIS Consortium, Inc., it is a comprehensive specification of a software framework for access to geodata and geoprocessing resources, and gives software developers around the world a detailed common interface template for writing software that will interoperate with other OpenGIS -conformable software written by other software developers.The research content in this paper is some key techniques on spatial database in GIS. Our vision is to manager 3D spatial objects by relational database management system and to manipulate the 0-dimensional object, 1 -dimensional, 2-dimensional, and 3 -dimensional in unifiable manner. We employ the mature technology of Object-Relational database in existence to solve some complex problems of spatial operations efficiently.In three dimensions, the basis of spatial objects is Euclidean geometry, it obeys Euclidean axioms. This leads directly to the question how geometric constructions, as defined by the Euclidean axioms, can be represented with the finite approximations available in computer systems. For example, on condition that there is an intersection point of two lines, one assumed that the intersection point can be computed precisely. However, computers work with finite representation and can represent coordinates only approximately. It is usually necessary to round the coordinates of the intersection point to the nearest grid point. This introduces some errors, e.g., a subsequent test will tell you that the intersection point does not lie on either of the two lines that create it in the first place. It violates Euclidean axioms, so is in the implement of GIS, e.g., the determined result of overlap usually failed for two simple spatial objects. In order to overcome those shortages, we define the Regularly Spatial Discrete Domains (RSDD), RSDD-based Primary Objects (RPOs), RSDD-based Objects (ROs). The character of those objects we have defined is that the coordinates of its vertexes or end-points are integers. The concept of RSDD can solve the conflict between the infinite precision real numbers of spatial object and the finite precision number systems of computers. Then we can preserve the closure of spatial operations and RSDD spatial data types.For the closure of spatial operations about ROs, we have studied the intersection between RPOs and gained the restructure algorithms, i.e., redraw a RPO-line, reconstruct a RPO-plane, and reconstruct a RPO-solid. We have researched the operations on ROs and obtained the operation algorithms about inserting a RPO-point, a RPO-line, aRPO-plane, and a RPO-solid into a RO.Taking advantage of Egenhofer's 9-intersection model, we have analyzed the topological relation between 3D spatial objects. By enumerating the regulations of decided the topological relation and eliminated conditions, among 512 possible topological relations, we have known the number of possible relation between lines is 33, between line and plane is 31, between line and solid is 19, between planes is 38, between plane and solid is 19, between solids is 8, between points is 2, between point and other objects else is 3, and we have presented the 9-intersection matrix corresponding to every relation. Specially, we have researched the topological relation between ROs and the measurement of ROs.Object-Relational database technique is a mature database technique, in the chapter 4, we have investigated the technology that using relational schema manager spatial objects, and given a general method or strategy. It is a feasible way to manager spatial objects by utilizing relational database in the GIS applications.We have brought to octa-tree index structure for managering spatial data efficiently in relational schema. By space filling curve, z-curve, we mapped RSDD to 1-dimensional linear sp...
Keywords/Search Tags:OpenGIS Specification, RSDD, RO, 9-Intersection Model, Topological Relation, Octa-tree, z-Curve, Geographical Information System (GIS), Spatial Database, Relational Database, Spatial Query, Spatial Index.
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