Cardinal directions on extended objects for qualitative navigation

With the aim of simulating the human reasoning process about spatial aspects such as orientation, distance and cardinal directions, several qualitative models have been developed in the last years. However, there is no model for representing and reasoning with all these spatial aspects in a uniform way. In the approach presented in this paper, this integration has been accomplished thanks to consider each type of spatial relationship an instance of the Constraint Satisfaction Problem. Constraint Logic Programming instantiated to Finite Domains extended with Constraint Handling Rules is a programming paradigm which provides the suited level of abstraction to define an incremental, flexible, efficient -with polynomial cost- and general purpose Constraint Solver (CS) for each one of the spatial aspects to be integrated. Moreover, it also allows the use of point and extended objects as primitive of reasoning. The corresponding CS for cardinal directions is described in this paper. This model has been applied to the development of a Qualitative Navigator Simulator.