Welcome to Information Visualization! I am delighted to be able to introduce to you the first issue of the peer-reviewed international journal dedicated to the research and practice of information visualization. The new journal will cover a variety of aspects of information visualization, ranging from fundamental research to practical applications. Information Visualization aims to provide a forum that can accommodate not only the unique focus of information visualization, but also the diverse interests of researchers and practitioners from an increasing number of disciplines.

This article is extracted and adapted from Ben Shneiderman's newly revised and recently published book, Designing the User Interface: Strategies for Effective Human---Computer Interaction (Third Edition), Addison Wesley Longman, Copyright 1998, with the permission of the publisher.

Large 2D information spaces, such as maps, images, or abstract visualizations, require views at various level of detail: Close ups to inspect details, overviews to maintain (literally) an overview. Users often switch between these views. We discuss how smooth animations from one view to another can be defined. To this end, a metric on the effect of simultaneous zooming and panning is de- fined, based on an estimate of the perceived velocity. Optimal is defined as smooth and efficient. Given the metric, these terms can be translated into a computational model, which is used to calculate an analytic solution for optimal animations. The model has two free parameters: animation speed and zoom/pan trade-off. A user experiment to find good values for these is described.

A number of taxonomies to classify and categorize software visualization systems have been proposed in the past. Most notable are those presented by Price [1993] and Roman [1993]. While these taxonomies are an accurate representation of software visualization issues, they are somewhat skewed with respect to current research areas on software visualization. We revisit this important work and propose a number of realignments with respect to addressing the software engineering tasks of large-scale development and maintenance. We propose a framework to emphasize the general tasks of understanding and analysis during development and maintenance of large-scale software systems. Five dimensions relating to the what, where, how, who, and why of software visualization make up this framework. The focus of this work is not so much as to classify software visualization system, but to point out the need for matching the method with the task. Lastly, a number of software visualization systems are examined under our framework to highlight the particular problems each addresses.

This paper introduces the video collage, a novel effective interface for browsing and interpreting video collections. The paper discusses how collages are automatically produced, illustrates their use, and evaluates their effectiveness as summaries across news stories. Collages are presentations of text and images derived from multiple video sources, which provide an interactive visualization for a set of video documents, summarizing their contents and providing a navigation aid for further exploration. The dynamic creation of collages is based on user context, e.g., an originating query, coupled with automatic processing to refine the candidate imagery. Named entity identification and common phrase extraction provides descriptive text. The dynamic manipulation of collages allows user-directed browsing and reveals additional detail. The utility of collages as summaries is examined with respect to other published news summaries.

Moments before the launch of every space vehicle, engineering discipline specialists must make a critical go/no-go decision. The cost of a false positive, allowing a launch in spite of a fault, or a false negative, stopping a potentially successful launch, can be measured in the tens of millions of dollars, not including the cost in morale and other more intangible detriments. The Aerospace Corporation is responsible for providing engineering assessments critical to the go/no-go decision for every Department of Defense space vehicle. These assessments are made by constantly monitoring streaming telemetry data in the hours before launch. We will introduce VizTree, a novel time-series visualization tool to aid the Aerospace analysts who must make these engineering assessments. VizTree was developed at the University of California, Riverside and is unique in that the same tool is used for mining archival data and monitoring incoming live telemetry. The use of a single tool for both aspects of the task allows a natural and intuitive transfer of mined knowledge to the monitoring task. Our visualization approach works by transforming the time series into a symbolic representation, and encoding the data in a modified suffix tree in which the frequency and other properties of patterns are mapped onto colors and other visual properties. We demonstrate the utility of our system by comparing it with state-of-the-art batch algorithms on several real and synthetic datasets.

This paper describes a comparative experiment with five wellknown tree visualization systems, and Windows Explorer as a baseline system. Subjects performed tasks relating to the structure of a directory hierarchy, and to attributes of files and directories. Task completion times, correctness and user satisfaction were measured, and video recordings of subjects ’ interaction with the systems were made. Significant system and task type effects and an interaction between system and task type were found. Qualitative analyses of the video recordings were thereupon conducted to determine reasons for the observed differences, resulting in several findings and design recommendations as well as implications for future experiments with tree visualization systems.

Although both statistical methods and visualizations have been used by network analysts, exploratory data analysis remains a challenge. We propose that a tight integration of these technologies in an interactive exploratory tool could dramatically speed insight development. To test the power of this integrated approach, we created a novel social network analysis tool, SocialAction, and conducted four long-term case studies with domain experts, each working on unique data sets with unique problems. The structured replicated case studies show that the integrated approach in SocialAction led to significant discoveries by a political analyst, a bibliometrician, a healthcare consultant, and a counter-terrorism researcher. Our contributions demonstrate that the tight integration of statistics and visualizations improves exploratory data analysis, and that our evaluation methodology for long-term case studies captures the research strategies of data analysts.

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In this paper we present several extensions to the wellknown InfoViz technique of parallel coordinates, mainly concentrating on brushing and focus+context visualization. First, we propose angular brushing as a new approach to high-light rational data-properties, i.e., features which depend on two data dimensions (instead of one). We also demonstrate smooth brushing of parallel coordinates as an intuitive tool for specifying non-binary degree-of-interest functions (then used for F+C visualization). Thirdly, we show how composite brushes provide lots of flexibility during data exploration. Additionally, we also present several further and more general extensions to parallel coordinates which there are (a) histograms to be used as axis overlays, (b) interaction features such as axis re-ordering, flipping, scaling and panning, and (c) detail on demand, implemented as a mouse-over effect.