Modeling the structure of cartographic information for query processing
TIMOTHY L. NYERGES · OhioLink ETD Center (Ohio Library and Information Network) · 1980
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.