Hypermedia – Maps and Overiew Diagrams
2.3 Maps and Overview Diagrams
Maps serve to improve spatial context in a hypertext network. The Intermedia view of a map is a local tracking map that displays all the documents or nodes linked to the current document which is dynamically updated. This ensures that correct information is always available; it also allows link previewing. Selecting a link marker will highlight the corresponding link line allowing the user to get an idea of the target without actually following the link [Utting & Yankelovich, 1989].
Overview diagrams, both at the local and global levels, serve as excellent navigational aids. Global overview diagrams provide an overall picture and can also serve as anchors for local overview diagrams. Local overview diagrams provide a fine-grained picture of the local neighborhood of a node. Overview diagrams for large systems might become complex and might introduce navigational problems of their own [Nielsen, 1990a]. Nielsen feels that in order to reduce the propagation of links from the local diagrams to global diagrams, weights can be assigned to the links based on their relevance to the user; this will trim the edges of the graph at the global level. Also, anchors can be differentiated, graphically, based on their estimated relevance to the users. Statistical analysis of the most frequently traversed links by a number of users might provide valuable insights into developing system-generated overview diagrams.