A spatial data model underlying human interaction with object-oriented spatial databases

Abstract

In geographic maps, objects are represented in a context extremely rich of relationships among them, either one-toone or many-to-many. Unfortunately, all these relationships can not be directly represented in the database scheme, nevertheless, it should be possible to show them to the user during the interaction.To manage this problem, we refer to a two-level database architecture with an object-oriented data model at the bottom level (the logic level), and an interaction model at the top level. The spatial data model given in this paper is an essential part of the interaction model. Our spatial data model is a conceptual tool that enhances the object-oriented model with spatial relationships between objects. In this way, it is supposed to be an effective tool for the designer of the human computer interaction environment, who takes the charge of constructing user views and browsinglquerying paradigms.Specijically. basic features of the spatial data model that will be outlined in this paper are: to point out the relationships among objects to be shown in the views, to d&ne data structures suitable for navigating among database objects, and, finally, to provide a simple and powerful calculus for posing spatial queries against the database.

A small set of formal topological relationships suitable for end-user interaction

“…In two-dimensional space, the intersection set S can now be either (empty), 0D (point), 1D (line), or 2D (area). At rst sight, these 4 possibilities might result into 4 4 (2 cases) : This is due to the fact that the dimension of the intersection cannot be higher than the lowest dimension of the two operands of the intersection dim(@A) = 1 , dim(A ) = 2 , dim(@L) = 0, and dim(L ) = 1. Further, the de nitions of line and area features exclude the option that dim(S 4 ) = 0 : Therefore, instead of 256, there are only 2 3 2 2 = 24 possible cases.…”