Topological Consistency for Collapse Operation in Multi-scale Databases

When we derive multi-scale databases from a source spatial database, the geometries and topological relations, which are a kind of constraints defined explicitly or implicitly in the source database, are transformed. It means that the derived databases should be checked to see if or not the constraints are respected during a derivation process. In this paper, we focus on the topological consistency between the source and derived databases, which is one of the important constraints to respect. In particular, we deal with the method of assessment of topological consistency, when 2-dimensional objects are collapsed to 1-dimensional ones. We introduce 8 topological relations between 2-dimensional objects and 19 topological relations between 1-dimensional and 2-dimensional objects. Then we propose four different strategies to convert the 8 topological relations in the source database to the 19 topological relations in the target database. A case study shows that these strategies guarantee the topological consistency between multi-scale databases.