|InfoVis.net>Magazine>message nļ 62||Published 2001-10-15|
|Tambiťn disponible en EspaŮol|
The digital magazine of InfoVis.net
As we have already seen in issue number 26 the semantic web is an initiative led by Tim Berners-Lee to grant access to the information residing in the Net not only to humans but also to machines.
Some companies are beginning to use the semantic contents (the meaning of their contents) that has begun to be codified in the web sites in order to improve the search procedures of relevant information. Some examples of this are Amazon.com or Yahoo shopping. But the semantic contents of a web site can be used advantageously for the visualisation of its information, since we already have the knowledge about the meaning and the existing relations between the concepts used in it.
Among the companies that are working in this direction in Europe we find Aidministrator, a Dutch company devoted to information presentation & distribution that has developed an interesting visualisation system based on the semantic contents (the ontology) of a web site.¬†
The approach that Aidministrator takes is to consider that in any visualisation procedure you begin with the raw data. This data is then organised, filtered and classified until it constitutes a semantic structure that provides a coherent meaning. Once this is accomplished the obtained structure serves as the basis to produce the visualisation.¬†
As they themselves say in their paper "Ontology based Information Visualisation"* this is a "generic procedure that is commonly used in information presentation tasks, ranging from constructing a lecture to designing a website", first you decide what to show (the structure) and then how to do it (the visualisation).
The Aidministrator system represents the ontology codified in a web site, (see the attached¬† images), as a system of text labels and spheres connected by straight lines.¬†
All these elements are located in space through a system of attraction and repulsion between the objects (as if you had springs inside the lines) This system keeps them in a dynamic balance that makes the objects that are semantically close appear spatially close, and the objects that are semantically far away appear in distant locations.
In this context "semantically close" means that two classes share many instances or that two instances belong to the same class.
For example, Fig. 2 depicts the contents of a Dutch web site of a job-agency. The ontology classifies the jobs by economic sector: recreation, finance, education, etc. Visualising this ontology using the visual metaphor of the spheres connected by "springs" allows us to immediately detect some trends and patterns as well as outliers.
The objective of Aidminstrator is to use this visualisation technique for:
The semantic web is beginning to be deployed timidly. As in other fields, the knowledge of the semantic contents will help enormously to visualise the information. As we have seen there are already companies working on that.
* Ontology based Information Visualisation, Proceedings of the Vth International Conference on Information Visualisation, London July 25-27, 2001, IEEE¬†
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