Uniform resource visualization

Computing environments continue to increase in scale, heterogeneity, and hierarchy, with resource usage varying dynamically during program execution. Computational and data grids and distributed collaboration environments are examples. To understand performance and gain insights into developing applications that efficiently use system resources, performance visualization has proven useful. Performance visualization tools, however, often are specific to a particular resource at a certain level of the system, possibly with fixed views. Thus, they limit a user\u27s ability to observe a performance problem associated with multiple resources across system levels and platforms. To address this limitation, information integration is necessary. In this research, we propose a new performance visualization framework, Uniform Resource Visualization (URV), focusing on integration of performance information into system-level visualizations. The goal of URV research is to systemize the performance visualization of resources with reusable and composable visualizations

Interactive, visual fault localization support for end-user programmers

End-user programmers are writing an unprecedented number of programs, primarily using languages and environments that incorporate a number of interactive and visual programming techniques. To help these users debug these programs, we have developed an entirely visual, interactive approach to fault localization. This paper presents the approach. We also present the results of a think-aloud study that examined the interactive, human-centric issues that arise in end-user debugging using a fault localization strategy. Our results provide insights into the contributions such strategies can make to the end-user debugging process.Keywords: visual fault localization, debugging, end-user software engineering, slicing, form-based visual programs, testing, end-user programmin

Doctor of Philosophy

dissertationVisualization has emerged as an effective means to quickly obtain insight from raw data. While simple computer programs can generate simple visualizations, and while there has been constant progress in sophisticated algorithms and techniques for generating insightful pictorial descriptions of complex data, the process of building visualizations remains a major bottleneck in data exploration. In this thesis, we present the main design and implementation aspects of VisTrails, a system designed around the idea of transparently capturing the exploration process that leads to a particular visualization. In particular, VisTrails explores the idea of provenance management in visualization systems: keeping extensive metadata about how the visualizations were created and how they relate to one another. This thesis presents the provenance data model in VisTrails, which can be easily adopted by existing visualization systems and libraries. This lightweight model entirely captures the exploration process of the user, and it can be seen as an electronic analogue of the scientific notebook. The provenance metadata collected during the creation of pipelines can be reused to suggest similar content in related visualizations and guide semi-automated changes. This thesis presents the idea of building visualizations by analogy in a system that allows users to change many visualizations at once, without requiring them to interact with the visualization specifications. It then proposes techniques to help users construct pipelines by consensus, automatically suggesting completions based on a database of previously created pipelines. By presenting these predictions in a carefully designed interface, users can create visualizations and other data products more efficiently because they can augment their normal work patterns with the suggested completions. VisTrails leverages the workflow specifications to identify and avoid redundant operations. This optimization is especially useful while exploring multiple visualizations. When variations of the same pipeline need to be executed, substantial speedups can be obtained by caching the results of overlapping subsequences of the pipelines. We present the design decisions behind the execution engine, and how it easily supports the execution of arbitrary third-party modules. These specifications also facilitate the reproduction of previous results. We will present a description of an infrastructure that makes the workflows a complete description of the computational processes, including information necessary to identify and install necessary system libraries. In an environment where effective visualization and data analysis tasks combine many different software packages, this infrastructure can mean the difference between being able to replicate published results and getting lost in a sea of software dependencies and missing libraries. The thesis concludes with a discussion of the system architecture, design decisions and learned lessons in VisTrails. This discussion is meant to clarify the issues present in creating a system based around a provenance tracking engine, and should help implementors decide how to best incorporate these notions into their own systems

Space-time multiresolution approach to atomistic visualization

Time-varying three-dimensional positional atomistic data are rich in spatial and temporal information. The problem is to understand them. This work offers multiple approaches that enable such understanding. An interactive atomistic visualization system is developed integrating complex analyses with visualization to present the data on space-time multiresolution basis facilitating the information extraction and generate understanding. This work also shows the usefulness of such an integrated approach. The information obtained from the analyses represents the system at multiple length and time scales. Radial distribution function (RDF) provides a complete average spatial map of the distribution of the atoms in the system which is probed to explore the system at different length scales. Coordination environments and cluster structures are visualized to look at the short range structures. Rings are visualized to understand the medium range structure. Displacement data and covariance matrices are visualized to understand the dynamical behaviors. Combinations of rendering techniques including animation, color map, sphere, polygonal and ellipsoid representations, pathlines and glyphs are used during the visualization process. The three-dimensional atomic configurations are reproduced accurately during rendering because of their physical significance while attributes such as coordination number, coordination stability and atomic species lack direct physical relevance and provide additional flexibilities in rendering. The performance results show interactive frame rates are achievable for systems consisting upto a thousand atoms. Such systems are typical of the systems simulated using first principles molecular dynamics simulations. The effectiveness and the usefulness of this work are justified for complex material systems using silicate and oxide liquids for visual analyses. The exploratory approach taken here has not been reported anywhere else before. The major contributions of this works are: 1. A new approach to the atomistic visualization advocating a formal integration of data analyses into the visualization system to improve the effectiveness and also present an implementation of the exploratory atomistic visualization system with integrated spatio-temporal analytical techniques. 2. The modeling of coordination environments, stability of the coordination environments, clusters, ring structures and diffusion for individual atoms. 3. The use of the visualization system for visual analysis of various liquid mineral systems of geophysical relevance

Set-Based User Interaction

This work demonstrates specific ways that the design of computer user interfaces can influence how individuals structure the problem solving process. In particular, an observational study of expert users of an image manipulation application indicates that current user interfaces make it difficult to explore sets of alternatives in parallel, despite this being a common problem solving practice. As a consequence, individuals tend to engage in highly linear problem solving processes. To address this problem, this work introduces the concept of a set-based interface, or an interface that facilitates the generation, manipulation, evaluation, and management of sets of alternative solutions. The concepts of a set-based interface are demonstrated in two tools, Side Views and Parallel Pies, both designed for use in the domain of image manipulation. Side Views automatically generates sets of previews for one or more commands and their parameters, enabling side-by-side comparison of alternatives. Parallel Pies streamlines the process of forking, or the act of creating new, standalone alternatives, and provides a visualization to evaluate results. Two controlled laboratory studies and a third think-aloud study reveal that these tools lead to users more broadly exploring the solution space and developing more optimal solutions for some types of tasks. These studies also show that the ability to broadly explore can initially be overused, adversely affecting solution quality if not enough time is spent maturing a single solution instance. This enthusiastic use of exploration tools is especially notable because such features are entirely optional to developing a solution. As such, these results suggest the need to further research ways user interfaces can support individuals in rapidly generating sets of alternative solutions. To support future research in this direction, this work contributes a set of metrics for quantifying breadth and depth of exploration; backtracking; and dead-ends in the problem solving process. A visualization called a process diagram aids in communicating these concepts.Ph.D.Committee Chair: Mynatt, Elizabeth; Committee Member: Abowd, Gregory; Committee Member: Hudson, Scott; Committee Member: MacIntyre, Blair; Committee Member: Nakakoji, Kumiy