Pictorial representations are very useful for humans to understand complicated relations or structures. This is the reason that the user interface of information systems is strongly required to visualize many kinds of information in a wide variety of graphical forms. At present, however, only some very specialized visualization techniques have been developed probably because the generality in the visualization has not been appreciated correctly. This book presents a visualization framework for translating abstract objects and relations, typically represented in textual forms, into pictorial representations, and describes a general visualization interface based on this framework. In the framework, abstract objects and relations are mapped to graphical objects and relations by user-defined mapping rules. The declarative nature of the mapping rules provides users with more global and more flexible layout capabilities. Also presented is an algorithm for drawing general undirected graphs which can be used to visualize network structures as network diagrams. The proposed visualization framework is shown to be general enough to be applied to various types of visualization problems, such as the visualization of semantics of natural language sentences, the generation of diagrams for data structures and program structures, and the drawing of database schema. Examples of all these problems are shown with actual mapping rules and pictorial results.
