Topological information are the most important kind of qualitative spatial information. Current formalisms for the topological aspect of space focus on relations between regions or properties of regions. This work provides a qualitative model for representing the topological internal structure of complex regions, which could be of multiple pieces and or have holes and islands to any finite level. We propose a layered graph model for representing the internal structure of complex plane regions, where each node represents the closure of a connected component of the interior or the exterior of a complex region. The model provides a complete representation in the sense that the (global) nine-intersections between the interiors, the boundaries, and the exteriors of two complex regions can be determined by the (local) RCC8 topological relations between the associated simple regions. Moreover, this graph model has an inherent hierarchy which could be exploited for map generalization.
The notion of composite region is first introduced in @cite_6 , where two components are allowed to meet at more than one points. This implies that the region in Figure (c) is considered as a composite region. This is the only difference between ours and that of @cite_6 .
@cite_6
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Spatial data are at the core of many scientific information systems. The design of suitable query languages for spatial data retrieval and analysis is still an issue on the cutting edge of research. The primary requirement of these languages is to support spatial operators. Unfortunately, current systems support only simplified abstractions of geographic objects based on simple regions which are usually not sufficient to deal with the complexity of the geographic reality. Composite regions, which are regions made up of several components, are necessary to overcome those limits. The paper introduces a two-level formal model suitable for representing topological relationships among composite regions. The contribution gives the needed formal background for adding composite regions inside a spatial query language with the purpose of answering topological queries on complex geographic objects.