Radial, space-filling visualizations can be useful for depicting information hierarchies, but they suffer from one major problem. As the hierarchy grows in size, many items become small, peripheral slices that are difficult to distinguish. We have developed three visualization/interaction techniques that provide flexible browsing of the display. The techniques allow viewers to examine the small items in detail while providing context within the entire information hierarchy. Additionally, smooth transitions between views help users maintain orientation within the complete information space.

Ordered, labeled trees are trees in which each node has a label and the left-to-right order of its children (if it has any) is fixed. Such trees have many applications in vision, pattern recognition, molecular biology, programming compilation and natural language processing. Many of the applications involve comparing trees or retrieving/extracting information from a repository of trees. Examples include classification of unknown patterns, analysis of newly sequenced RNA structures, semantic taxonomy for dictionary definitions, generation of interpreters for nonprocedural programming languages, and automatic error recovery and correction for programming languages. Previous systems use exact matching (or generalized regular expression matching) for tree comparison. This paper presents a system, called Approximate-Tree-By-Example (ATBE), which allows inexact matching of trees. The ATBE system interacts with the user through a simple, but powerful query language; graphical devices a...

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This paper describes fractal approaches to the problems which associate with visualizing huge hierarchies. The geometrical characteristic of a fractal, selfsimilarity, allows users to visually interact with a huge tree in the same manner at every level of the tree. The fractal dimension, a measure of complexity, makes it possible to control the total amount of displayed nodes. A prototype visualization system for UNIX directories is also shown. 1 Introduction Visualization systems for hierarchical structures, especially for huge 1 data structures, have a potential usefulness. For example, the visualization of whole UNIX directories might help system administrators to maintain the file systems. Since administrators could recognize, through the visualization, local file systems of each computer and remote file systems mounted by using NFS (Network File System), they might avoid mistakes, such as deleting or moving files which are being referenced by other computers. It is, however, m...

Visualization of object-oriented programs by class diagrams is a widely used technique. So far no commonly agreed aesthetic criteria have been recorded in order to standardize and measure the quality of class diagrams. In this paper we focus on UML class diagrams, the standard notation for class diagrams in software engineering. We propose some aesthetic criteria which reflect the highly sophisticated features of UML class diagrams, a layout algorithm which respects all these features and an implementation of a graph drawing framework which is able to produce drawings according to these criteria.

Graphs are ubiquitous, finding applications in domains ranging from software engineering to computational biology. While graph theory and graph algorithms are some of the oldest, most studied fields in computer science, the problem of visualizing graphs is comparatively young. This problem, known as graph drawing, is that of transforming combinatorial graphs into geometric drawings for the purpose of visualization. Most published algorithms for drawing general graphs model the drawing problem with a physical analogy, representing a graph as a system of springs and other physical elements and then simulating the relaxation of this physical system. Solving the graph drawing problem involves both choosing a physical model and then using numerical optimization to simulate the physical system. In this

Various algorithms have been proposed for the difficult problem of producing aesthetically pleasing drawings of trees, see [15, 17] but implementations only exist as "special purpose software", designed for special environments. Therefore, many users resort to the drawing facilities available on most personal computers, but the figures obtained in this way still look "hand-drawn"; their quality is inferior to the quality of the surrounding text that can be realized by today's high quality text processing systems. In this paper we present an entirely new solution that integrates a tree drawing algorithm into one of the best text processing systems available. More precisely, we present a T E X macro package TreeT E X that produces a drawing of a tree from a purely logical description. Our approach has three advantages. First, labels for nodes can be handled in a reasonable way. On the one hand, the tree drawing algorithm can compute the widths of the labels and take them into account for...

The Hy+ system is a generic visualization tool that supports a novel visual query language called GraphLog. In Hy+ , visualizations are based on a graphical formalism that allows comprehensible representations of databases, queries, and query answers to be interactively manipulated. This paper describes the design, architecture and features of Hy+ with a number of applications in software engineering and network management. These examples demonstrate the benefits of using a visualization-based system to carry out tasks of ever-increasing complexity in these areas and others.

This paper addresses the general issue of the aesthetic layout of such trees. Two algorithms are presented for the layout of generalized trees, and general issues, such as appropriate aesthetics, are discussed. The algorithms described are suitable for such tasks as the layout of class hierarchies, directory trees and tableau-style proofs

Event sequence analysis is an important task in many domains: medical researchers study the patterns of transfers within the hospital for quality control; transportation experts study accident response logs to identify best practices. In most cases they deal with more than thousands of records. While previous research has focused on searching and browsing, overview tasks are often overlooked. We introduce a novel interactive visual overview of event sequences called LifeFlow. LifeFlow scales to any number of records, summarizes all possible sequences, and highlights the temporal spacing of the events within sequences. We conducted two case studies with healthcare and transportation domain experts to illustrate the usefulness of LifeFlow. We also conducted a user study with ten participants which confirmed that after 15 minutes of training novice users were able to rapidly answer questions about the prevalence and temporal characteristics of sequences, find anomalies, and gain significant insight from the data.