3D Topology Rules Implementation in Spatial Database

Topological information consists of connectivity, adjacency and containment properties which describes relationships between 3D objects. This information provides the basis for more complex 3D spatial analyses. However, only 2D topology rules are available in spatial databases. Consequently, the results based on a 2D topology will also be limited to 2D. This hinders the capabilities of a spatial database in handling 3D data. This study proposed an implementation of 3D topology rules within a spatial database to define valid topological relationships between 3D objects. A 36-Intersection Model that describes intersections between objects interiors, boundaries and exteriors were developed as an additional PL/SQL script for Oracle spatial database. The intersections included ten topological groups with dimension of intersection from 0 to 3D, which are point-to-point, point-to-line, point-to-region, point-to-volume, line-to-line, line-to-region, line-to-volume, region-to-region, region-to-volume and volume-to-volume. Six cases were tested which included 3D objects with disjoint, meet (touches), equals, contains, inside (within) and overlaps topological relationship. As a result, the intersection matrix describing the dimension of intersections between objects could be determined. The 36IM topology rules were able to determine the topological relationships between 3D objects without requiring object decomposition and additional storage. Therefore, 3D topology rules are a lightweight but effective method to maintain topological information between 3D objects.