Cardinal Direction Relations in Qualitative Spatial Reasoning

Representation and reasoning with spatial information is a fundamental aspect of artificial intelligence. Qualitative methods have become prominent in spatial reasoning. In geophysical explorations, one of the aspects is to determine compass direction between the regions. In this paper, we present an efficient approach to cardinal directions between free form regions. The development is very simple, mathematically sound and can be implemented efficiently. The extension to 3D is seamless; it needs no additional formulation for transition from 2D to 3D. It has no adverse impact on the computational efficiency, as the technique is akin to 2D. This work is directly applicable to geographical information systems for location determination, robot navigation, and spatio-temporal networks databases where direction changes frequently.