Dimitris Papadias,
Max Egenhofer, and Jayant Sharma 4th ACM Workshop on Advances in Geographic Information Systems, Rockville, MD,
S. Shekhar and P. Bergougnoux (eds.), pp. 107-114, November 1996.
Abstract
Spatial reasoning is an important area of GIS and Spatial
Databases research. This paper deals with reasoning about direction
relations (east, northeast) in geographic hierarchies. We assume a
database that stores the direction relations between objects in the
same geographic entity and propose algorithms for the inference of
relations between objects in different entities. We present two
types of inference: the first one uses the relations of ancestor
regions, while the second is based on composition of spatial
relations and path consistency. For both types we provide inference
rules, illustrate examples, and study the computational complexity.
Although we use a specific set of relations for demonstration
purposes, the algorithms are applicable to any set of direction
relations provided with appropriate inference rules.
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Dimitris Papadias,
Max Egenhofer, and 
Jayant Sharma