Storing and handling vague spatial objects

This paper deals with the storage and manipulation of vague spatial objects: points, lines, and regions. Vector data format is used to implement vague objects. We store vague objects by extending GRASS vector format capabilities. A point is represented by a triple, containing the location and the membership value of the point. A line is represented by a sequence of triples, each containing the location and the membership value of a point on the line. A region is represented by a set of lines, which depict important characteristics of the region. Data structures are defined to put constraints on the stored data, so that desired properties for vague objects are satisfied. To complete (approximate) information about lines and regions, a linear interpolation and a triangulation-based interpolation method are used, respectively. Modules are built to edit and retrieve information of vague objects. A union operator on vague objects is also implemented.