Modeling the structure of cartographic information for query processing

Concepts from Cartography, Linguistics, Picture Processing and Data Base Theory are utilized in modeling the structure of cartographic information in virtual maps. Two types of virtual maps are considered: a cartographic display on a CRT screen and a cartographic data base. Data bases are discussed in terms of six levels of data organization: data reality, information structure, canonical structure, data structure, storage structure and machine encoding. A linguistic model that characterizes a cartographic information structure is presented. A multi-dimensional grammar serves as the basis of the linguistic model. The grammar is composed of production rules, lexical rules, transformational rules and a vocabulary of nonterminal and terminal cartographic objects. Production rules and lexical rules are used to generate the underlying, conceptual structure among nonterminal objects of a virtual map. Transformational rules operate on the ordering of nonterminal objects to produce a cartographic display of the terminal objects. An information structure serves as the logical organization of an information base (INBASE). An INBASE, being an extended notion of a data base, includes conceptual information as well as empirical data utilized in cartographic query processing. Cartographic query processing is defined as a method of manipulation and display of cartographic information that employs a high-level language of English-like statements as a communication interface. A cartographic query system, CART-QUERY, developed to demonstrate the feasibility of information structuring is discussed and evaluated.