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Inf@Vis!

The digital magazine of InfoVis.net

About Walruses and Spirals
by Juan C. Dürsteler [message nº 43]

Multidimensional Information Visualisation is not easy to digest. The challenge is to find suitable visual models and metaphors.

To represent information that depends on more than 3 variables, i.e. in more than 3 dimensions is not an easy task. The main problem is not that you need a coherent mathematical formulation that models its behaviour and that furthermore should also be visually representable but that this representation has to be easily interpretable by people alien to the technical intricacies and internal details of the mathematical model.

For instance, the way the people navigate inside a web site can be represented by a graph of the navigation scheme (we spoke about graphs and some of their applications in the article on Connectivity). Nevertheless it's not an intuitive task to understand the behaviour of a web's visitors, especially when what you want to know is the global behaviour of large quantities of people acting at the same time and not only the trajectory of a few.

Some examples on navigation visualisation in a web site are accessible in the always-commendable Atlas of Cyberspaces. Most of them represent your particular navigation history in order to help you remember where you are and where you were.

A 3D graph visualisation tool, still in development, is Walrus. Its elaborated representations in the 3D hyperbolic space have a noticeable elegance and aesthetical beauty. They are devised for large quantities of nodes (a node can be a web page) and links (between 2 or more nodes). The gallery, where you can find several animations, is especially interesting.

In spite of the elegance of the realisation, the interpretation of such visualisation is by no means trivial. Maybe it's easy to build a mental idea of the nodes and its links, but it's not so easy to extract practical information and patterns that could provide an insight for the daily activity of a web manager.

Another interesting representation is Spiral (thanks to Cesar Martin for the link). Spiral is a representation of all the articles that the members of rhizome.org have contributed to over the last few years. A Spiral that winds and unwinds according to the movement of a slider represents the time line. Inside the spiral many small dots appear. Each of them is a particular article or contribution. The dots are ordered chronologically along the spiral and thematically in the transversal sense.

Spiral combines elegantly thematic and chronological information in a very attractive and clear representation. Nevertheless one question arises. Is it really much easier to find information using this representation than with the traditional textual table? There still aren't usability studies on this type of representations.

When the amount of data is overwhelming it is practically unfeasible to find patterns just by diving into the raw data. Information Visualisation just tries to solve this problem. Nevertheless to find clear and intuitive visualisations for complex and large problems is a very challenging task.

There is a lot of work still to be done.

Links of this issue:

http://www.infovis.net/printMag.php?num=28&lang=2  
http://www.cybergeography.com/atlas/surf.html  
http://www.caida.org/TOOLS/visualization/walrus  
http://www.caida.org/TOOLS/visualization/walrus/gallery  
http://rhizome.org/spiral  
http://rhizome.org/fresh/  
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