Navigation in Hypertext
Bird-eye View and Fish-eye View
These two approaches are used to display the hypertext's structure.
Bird-eye view's approach is to view the structure as a tree or forest, with "cross-reference" links as exceptions. In any case, the graph will most likely not fit on the screen. A scrolling window can be used to display parts of the graph. Also, one may zoom in and out in order to get a more or less detailed view [De Bra].
Fish-eye view's approach is to show the structure around the "current" node in detail, and show less detail as the distance from the current node grows [De Bra].
The main problem when generating fish-eye views (and also when zooming out in a birds-eye view) is how to decide which details can be left out, and which distortion of the structure is acceptable. One may need to start clustering nodes together, i.e. show composite structures which do not really exist in the hyperdocument and which are broken up as one comes closer to these nodes [De Bra].
Below is a small example of a birds-eye view and a fish-eye view.
Source: De Bra.
Birds-eye view and Fish-eye view become useful when hypertext systems get larger and site maps seem to be useless.
Last modified: 6 Nov 2002 by Kathy Nguyen Dang