We suggest to include spatial entities and corresponding spatial values as first class citizens in fact oriented models using ORM. A spatial entity is just a piece of some space. A spatial value is seen as a possibly infinite set of positions in some coordinate system. This makes the conceptual model very independent of the implementation platform. On this basis, we suggest a notation for spatial values. Further, we investigate some rather useful spatial constraints; the no overlap constraint and the no overlap exclusion constraint, which turn out to be spesializations of the uniqueness and the exclusion constraints. Finally, we discuss some possible implementation platforms.
Gerhard Skagestein: University of Oslo (Norway)
Håvard Tveite: Norwegian University of Life Sciences (Norway)