Peer Mylov

3D visual data mining: goals and experiences

The visual exploration of large databases raises a number of unresolved inference problems and calls for new interaction patterns between multiple disciplines--both at the conceptual and technical level. We present an approach that is based on the interaction of four disciplines: database systems, statistical analyses, perceptual and cognitive psychology, and scientific visualization. At the conceptual level we offer perceptual and cognitive insights to guide the information visualization process. We then choose cluster surfaces to exemplify the data mining process, to discuss the tasks involved, and to work out the interaction patterns.

The 3DVDM Approach: A Case Study with Clickstream Data

Clickstreams are among the most popular data sources because Web servers automatically record each action and the Web log entries promise to add up to a comprehensive description of behaviors of users. Clickstreams, however, are large and raise a number of unique challenges with respect to visual data mining. At the technical level the huge amount of data requires scalable solutions and limits the presentation to summary and model data. Equally challenging is the interpretation of the data at the conceptual level. Many analysis tools are able to produce different types of statistical charts. However, the step from statistical charts to comprehensive information about customer behavior is still largely unresolved. We propose a density surface based analysis of 3D data that uses state-of-the-art interaction techniques to explore the data at various granularities.

Using Nested Surfaces for Visual Detection of Structures in Databases

We define, compute, and evaluate nested surfacesfor the purpose of visual data mining. Nested surfaces enclose the data at various density levels, and make it possible to equalize the more and less pronounced structures in the data. This facilitates the detection of multiple structures, which is important for data mining where the less obvious relationships are often the most interesting ones. The experimental results illustrate that surfaces are fairly robust with respect to the number of observations, easy to perceive, and intuitive to interpret. We give a topology-based definition of nested surfaces and establish a relationship to the density of the data. Several algorithms are given that compute surface grids and surface contours, respectively.

Three Types of Multimedia Interactions — and Beyond

To understand the impact of these interactive multimedia it is first necessary to get an overview of their structure and characteristics. Interactivity is an invitation to engage in interactions, but these interactions will take place in some medium. In the following we shall present three such media based on their anchoring in the psychological constitution of the individual. They mediate interactions based on bodily actions, images and symbols. As the media may contain different sorts of units and their arrangement, this will lead us to some considerations concerning syntactic properties. Four types of syntax will be sufficient to catch the significant differences in the ordering of the content of multimedia. This also leads to a division or dichotomy in the medium for images. In return we will treat the medium for actions (interactions) as a special dimension. Interactivity as a feature of our environment means a certain measure of freedom on behalf of the user, and this might create problems in relation to the intended paths through the multimedia presentation. We shall comment on the question of narrative coherence and embark upon a further analysis of the medium for images and symbols (language) respectively, showing that they really are two autonomous substrata even if the symbolic medium may dominate. In connection with the question of syntax it will be demonstrated that interactions come in two different forms. By considering modern computer-based artworks it is possible to add a third form. After this we have three media, four types of syntax and three forms of interaction.