elektronická verzia publikácie - FIIT STU - Slovenská technická ...

288 Selected Studies on Software and Information Systems
lIKnow 2 ) or hierarchical clustering approaches can be implemented via Java applets,
using images or via SVG. Proper algorithms for the layout and abstraction level are
required as user interfaces can quickly become overloaded with information for large
or complex information spaces.
Figure 10-14. Example of visual navigation using graph visualization techniques in project AllIKnow.
Links are realized as graph nodes.
− Spatial visualization is often implemented via plug-ins, which enable users to move
freely in a two- or three-dimensional space and optionally interact with the objects it
contains. The most common visualization approaches are virtual maps, such as
Google Maps 3 (2D) or Geonova 4 (3D) (see Figure 10-15). However, the use of spatial
(3D) visualization on the Web is as of today not very common.
Other visualization approaches, which focus on the presentation of metadata can also be
successfully used to visualize link structures and thus navigation.
CropCircles is a topology sensitive approach to visualization of OWL class hierarchies
inspired by treemaps (Wang & Parsia, 2006). Since it visualizes (class) hierarchies, it
might be ideally suited for the visualization of facets, which contain restriction hierarchies
(see Figure 10-16). CropCircles provide quick overview of the topology (i.e. the size, depth
and complexity of a hierarchy), while also providing a visually pleasing nested presentation
of individual nodes.
2
AllIKnow: http://alliknow.net/ (last viewed 16.11.2006)
3
Google Maps: http://maps.google.com/ (last viewed 18.8.2009)
4
Geonova: http://www.geonova.ch/gvista/pages/ch/GVista.htm (last viewed 18.8.2009)