Spatial Relation Operations Based on V9i Model

Operations and description for spatial relations are important for GIS. At the present, investigations about them are mainly based on 9-intersection (9I) model for spatial relations. However, due to the infinity of the complements of objects in the model, it is difficult to directly capture the complements of objects. Therefore, even though most of spatial relations could be defined in the SDTS with aggregates of two or more 9-intersection primitives, it is difficult to calculate these primitives from spatial data, and further operations on spatial relations are also difficult. A new Voronoibased 9-intersection (V9I) model has been developed by some researchers, which redefines the exterior of spatial object with its Voronoi region instead of its complement. Since the exterior of the model is not infinite any more, it is possible to directly calculate and operate them, thereafter, it also becomes rather easy and realizable to manipulate spatial relations in a GIS system with this model. Based on the above idea, with the help of this model, this paper sets up a mechanism for manipulating and acquiring spatial relations from spatial data stored in a GIS database, and then defines and describes corresponding operations. Finally, this paper gives an experimental tool with Visual C++ on Windows platform.