Interacting with geographic databases: a focus+context approach

We present results on the design of a visual interaction environment for geographic information systems. We envision an exploration of the database where, starting from an abstract view, more detailed information is disclosed on demand, and visualized in a fish-eye view fashion. The interaction process is a sequence of views on the database, each displayed by a map in which topological properties are preserved. An efficient navigation requires the adoption of topological invariants for representing the views. Since each interaction step modifies only a portion of the current view, we propose an efficient incremental approach, which updates the current topological invariant by exploiting knowledge coming from previous steps. This approach is mainly based on the formalization of the interaction process starting from the notion of nested partition