The BUBBLEBROWSER is a proposed interface for the interactive visualization of the Rhizome database of art-objects and online articles. Implemented as a Java applet with an associated server-side component, its goals are to facilitate directed foraging in an environment of many loosely-related documents.
The BubbleBrowser is built around the metaphor of animated "information bubbles" which re-arrange themselves according to the visitors' interests. Objects in the Rhizome database are represented as "bubbles" which move about the surface of a three-dimensional sphere. The bubble nearest the center represents the visitor's current focus of attention (though any bubble can be inspected); the content of this central bubble structures the organization of the other bubbles around it. When a visitor selects a new bubble to examine, this bubble moves toward the center position, while new and different bubbles (corresponding to relevantly-related documents) percolate towards it from the periphery. As the system settles into an equilibrium, the BubbleBrowser produces the impression of a living, organic surface.
The BubbleBrowser is a so-called "focus+context" scheme, allowing the user to get an overview of a data space and to focus on details at the same time. To achieve this, it bases its geometrical transformation on the "hyperbolic tree", a non-Euclidean construction originally developed in the 19th century by the French mathematician Poincare. According to studies conducted at Xerox Parc, hyperbolic trees can be used to display up to 10 times as many nodes as a conventional 2D browser, making them an efficient and organized scheme for laying out large hierarchies. In the BubbleBrowser, as with other interactive hyperbolic trees, any node may be brought into focus by clicking on it and watching it smoothly migrate to the center in real-time.
The objects in the Rhizome database are richly related, but not necessarily heirarchically structured. For this reason the BubbleBrowser dispenses with the ball-and-stick metaphor typically used in hyperbolic trees, and instead uses a representation based on Voronoi partitions of the plane (also called Dirichlet domains). In this scheme, each data object is represented by a node point within a bubble-like cell, with the property that all of the points contained within that cell are closer to that node than any other. The Voronoi representation emphasizes similarity through adjacency, which we believe may be a more appropriate metaphor for the largely independent objects in the Rhizome database.
When animated, Voronoi cells have the additional advantage of a fun, squishy appearance. In the BubbleBrowser, Voronoi cells will be rendered with rounded Bezier peripheries, in order to enhance this impression. At the same time, they will also be color-coded in a variety of ways to indicate: their relevance to the current query, their per-session or per-cookie usage history (usage trail), their global frequency of retrieval (hitcount), and the real-time presence or interest of other users (on other BubbleBrowsers).
We predict that BubbleBrowser usage will consist of examination of closely-related information-clusters, alternating with larger leaps, across the BubbleBrowser's gradients of relatedness, into unrelated territory. To work as an efficient visualization, it will be necessary to estimate the relatedness of the Rhizome objects with respect to each other; to do this, we propose to implement a server-side statistical analysis program. This program, which will probably need to run nightly on the Rhizome server, will perform some variety of self-organizing clusterization, such as Hierarchical Agglomerative Clustering or Gaussian Mixture Modeling.
Appendix: Other possible representations in the BubbleBrowser.
1. THE SECRET LIVES
2. THE ALPHABET SYNTHESIS MACHINE.
4. THE WEBGRAPH
5. OBZOK @ SINGLECELL.
6. SMALL SKETCHES.