Queries Of Spatial Topological Relations Based On Oracle Spatial

The formalization and judgment of spatial topological relations plays an important role in modeling spatial data, spatial query, spatial analysis, spatial reasoning, updating spatial data and so on in Geographic Information System (GIS) and thus the formalization and judgment in computational models of spatial relations is critical to the advancement of geographical information science. Currently 9-intersection method is most popular to be used for the studies and application of judgment of spatial topological relations. Though there are some imperfections and deficiencies in theory, it is still a good method to judge the spatial relation of two spatial objects in application. So in Oracle9i, Oracle Spatial provides a SQL schema and functions that facilitate the judgment of spatial topological relations and it implements a 9-intersection model for categorizing binary topological relations between points, lines and polygons.The paper introduces some binary topological relations models and then according to their characteristics in computational model and the studies on the Oracle Spatial data including their models, storages, indexes and queries, the deficiencies of spatial relation operating of Oracle Spatial in differentiating binary topological relation by 9-intersection model is referred. Aiming at the deficiencies, the paper gives countermeasures and computational methods are designed.In the methods, a spatial object is divided into simpler objects and thus the matrix elements' values of 9-intersection model are easily obtained. Some values can be obtained directly by the judgment of topological relation which is defined byOracle Spatial and the others are made sure by operating spatial data type-SDO_GEOMETRY. Some topological relations are also referred that can be described directly including the relation betweens a region with a hole and a region without a hole.At last, the MapInfo7.0 Application is integrated with the VC++6.0 as a development in which the Oracle database is visited by 004O(Oracle Objects for OLE) C++ class libraries. Furthermore, experimental results with the practical and simulated Oracle spatial data show the reasonability and practicability of the new method for spatial topological relation queries.