Here is the paper abstract:

"The paper presents an extension to the Excentric Labeling, a labeling technique to dynamically show labels around a movable lens. Each labels refers to one object within the lens and is connected to it through a line. The original implementation has several known limitations and potential improvements that we address in this work, like: high density areas, uneven density distributions, and summary statistics. We describe the implemented extensions and present a think-aloud user study. The study shows that users can naturally understand and easily operate the majority of the implemented function but label scrolling, which requires additional research. From the study we also gained unanticipated requirements and interesting directions for further research."

The Motivation

The main motivation behind this technique and its relative study was a practical problem we encountered in the development of a new visualization. EL was just great and fit our need of understanding the content of screen regions. But the real problem was to have something flexible enough to deal with very sparse and very dense areas at the same time. In dense areas the original EL provided only a simple sampling mechanism that did not really help to interpret the data. Them while implementing a solution we discovered we could add some other useful and interesting features.

The Techniques

With the EEL we introduced the following features:

• Label scrolling: a mechanism to scroll through labels when there are to many of them.
  
  
• Focus area adjustment: an automatic mechanism to let the size of the focus area automatically adapt to the underlying data density.
  
  
• Summary statistics and filtering: a series of glyphs and interactive tools to summarize the content under the focus area and to disambiguate it through filtering.
  
  
• Inheritance of visual features: a visual mapping mechanism to let the labels inherit the visual/data features from their connected items.
  
  
• Layout and sorting: algorithms and techniques to permit effective positioning of labels and of their links to the items.
  

For the details you can download the paper.


The User Study
The user study we conducted is in my opinion a very interesting part of this work. We learned really a lot form it. For years discount usability studies have been promoted by people like Jakob Nielsen, especially in industry, but they are not very much loved or popular in research contexts; especially in InfoVis where evaluation in general yet struggles a bit to find its way. But if used as explorative tools, we discovered, they can be great!

Sure we received some critics, as our results cannot really tell a final word on whether the introduced features provide a measurable benefit. But what is often overlooked in academia is that the role of research is not only to provide answers but also to create new targeted and relevant questions. And discount or informal evaluation methods can be a great complement to our research toolbox.

We gathered 8 people and observed them while performing some predefined tasks we deemed relevant. The result was useful not only to perfect our work but also and foremost to generate some questions that we would not ask to ourselves otherwise. Observing your users using your visualization is alway an eye opener. There is a big gap between what you expect and what they do in reality. And within this gap there is a lot to learn!

Excentric or Eccentric?
Every spell checker I use highlights the word "excentric" as non existing and suggests "eccentric" instead. I did a little research and also well known dictionaries like the Merriam-Webster do not know it. By typing in Google "excentric definition" I can get some results but then they basically say it is a synonym of eccentric. Maybe someone among you have a clue on it?

By the way, maybe the next time I'll meet Jean Daniel or Catherine I will ask why they used excentric and not eccentric. My guess is that the cause is that the French word for it is "excentrique"? ;-). In doubt and for consistency reasons we decided to keep it as it is.