Ontology Visualizer

A tool for visualizing domain ontology structure using incremental visual browsing of the ontology.

Institution: Slovak University of Technology
Technologies used: Java, Apache Cocoon 2.1, Sesame 1.2.5
Inputs: Publication meta-data ontology
Outputs: Visualization of ontology structure

Addressed Problems

Effective visualization of large information spaces needs a sophisticated system of interactive navigation. Direct application of various layout algorithms obviously does not provide desired results, respectively often fails to provide desired view of information space mainly due to its complexity and visualization of the whole space at once.

However, the challenge of large open information spaces lies in providing a simple, yet effective way of finding, sorting and viewing relevant information. An effective means to accomplish these goals is the use of a faceted browser if the semantics of the information are known or if it is well structured.


The aim of this tool is to implement a method for effective visualization of structure of the metadata space. It is based on incremental browsing of an ontology structure. The method visualizes in every moment only specific part of the metadata space (a window) where the content of the space is selected according to evaluations of the presented entities (e.g., ontology classes). Entity evaluations are gained from interactions with the users of the ontology (people manually browsing or applications). We approach also cold start problem in order to support a user in effective start of the navigation within the metadata space.

The actual visualized information is filtered with combination of application of various filters to visualized data. Purpose of these operations is to visualize in actual context only classes estimated as the most important classes. Filtering is accomplished separately using an evaluation of importance level for each class.

The evaluation subsystem is monitoring ontology usage by external applications, processing observed actions and its parameters, and storing processed data necessary for the entity importance estimation. For monitoring usage of the ontology we use the SemanticLog software tool.