| One of the best ways for users to navigate in hypermedia systems is via an overview diagram of the information space. However, overview diagrams are difficult to construct because the diagrams represent visualizations of the information space of very large and complicated multidimensional network structures. It is extremely difficult to create an aesthetically-pleasing layout of an effective two or three dimensional projection of such a structure on a small screen that conveys all the required information.; This work develops strategies that make it easier to visualize the information space of hypermedia systems. First, dynamic bindings between the visual properties of the overview diagrams and the underlying information are used so that more information can be presented to the users through these views. Moreover, clustering techniques are used to form abstracted views of the space that can fit on the screen. A visualization strategy is developed which shows the abstracted views in three dimensions, smoothly integrating the detail and the context. Content-based and pattern-based filtering strategies are used so that only the information that the user finds useful is presented in the views. A method to find the important landmark nodes and show the context of nodes with respect to only the landmark nodes is also developed. Finally, an algorithm is developed that forms hierarchies from these complex network structures. Although the algorithm is automatic, it can be guided by the user so that multiple hierarchies giving different perspectives on the underlying information space can be formed. These multiple hierarchies can be visualized in various ways such as 2D and 3D trees, treemaps and hierarchically-indented table of contents.; These strategies, which use a combination of structural and content analysis of the underlying information space, are incorporated in a tool which allows the designers of hypermedia systems to interactively develop various types of visualizations. The requirements of an information visualization tool are identified and these requirements are incorporated in the tool. The potential usefulness of the tool is demonstrated by forming visualizations of the World-Wide Web. |
