GVU Technical Report Series

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Now showing 1 - 10 of 541
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    Applying Program Visualization Techniques to Aid Parallel and Distributed Program Development
    (Georgia Institute of Technology, 1991) Stasko, John T. ; Appelbe, William ; Kraemer, Eileen T. ; GVU Center
    Parallel and distributed programming is intrinsically more difficult than sequential programming, yet few effective tools or methodologies have been developed to help programmers understand the behavior of their parallel programs. Browsing source code and tracing program output are tedious and often ineffective approaches for parallel program understanding. Program visualization, which relates a program's behavior to the programmer's model of the system's components and interactions, has been shown to be a novel and highly effective approach to program and algorithm comprehension. Extending and adapting program visualization to parallel programming can aid comprehension of the complex concurrent events and transitions that occur in parallel programs. We are defining a model for the capture and display of parallel program events and transitions, based upon the path-transition paradigm for animation, and partial ordering of events. Using this model, we are developing a prototype for visualizing parallel programs, and testing the model and prototype upon a suite of scientific parallel programs.
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    (Georgia Institute of Technology, 2010) Fathi, Alireza ; Cunningham, Alex ; Paluri, Balmanohar ; Ni, Kai ; Dellaert, Frank ; GVU Center
    EasySLAM is a robust, accurate, efficient and easy-to-use visual SLAM framework which uses the unique properties of planar landmarks to navigate robots in societal settings. Due to the use of landmarks which can be associated with semantics, a hybrid symbolic-metric SLAM variant is obtained that makes the maps immediately usable for human-robot interaction, high-level monitoring, and semantic analysis. EasySLAM associates a set of landmarks to each part of the house (e.g. kitchen, living room, bathroom, bedroom, etc.) and takes navigation commands such as "go to kitchen". Loalization and mapping, planning and navigation results are presented with an inexpensive, commercially available robot and uniquely identifiable markers. SLAM with planar landmarks is easy, robust, and fills the real need in both research and society, and we have a system that everyone can use.
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    Context-Awareness in Wearable and Ubiquitous Computing
    (Georgia Institute of Technology, 1997) Abowd, Gregory D. ; Dey, Anind K. ; Orr, Robert J. ; Brotherton, Jason Alan ; GVU Center
    A common focus shared by researchers in mobile, ubiquitous and wearable computing is the attempt to break away from the traditional desktop computing paradigm. Computational services need to become as mobile as their users. Whether that service mobility is achieved by equipping the user with computational power or by instrumenting the environment, all services need to be extended to take advantage of the constantly changing context in which they are accessed. This paper will report on work done in the Future Computing Environments Group at Georgia Tech to provide infrastructure for context-aware computing. We will describe some of the fundamental issues involved in context-aware computing, solutions we have generated to provide a flexible infrastructure and several applications that take advantage of context awareness to allow freedom from traditional desktop computing.
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    An Environment to Support User Interface Evaluation Using Synchronized Video and Event Trace Recording
    (Georgia Institute of Technology, 1993) Badre, Albert N. ; Hudson, Scott E. ; Santos, Paulo J. ; GVU Center
    This paper presents a simple but very powerful technique to support user interface evaluation along with a prototype open environment -- I-Observe, the Interface OBServation, Evaluation, Recording, and Visualization Environment -- which supports a preliminary implementation of this technique. This technique operates by recording user interface sessions in multiple modalities, both as a trace of interesting events and through video images. It then provides tools to allow the user interface evaluator to combine these modalities, analyzing the event stream to search for patterns of interesting or important user actions, then using the recorded timestamps associated with these actions to present only the sections of the video recording of interest. This allows, for example, all places where the user invokes a help system or a particular command to be observed without requiring the evaluator to manually search the recording or sit through long sessions of unrelated interactions. By combining the precise recording of automatic event trace capture with the rich contextual information that can be captured in a video and audio recording, this technique allows analyses to be performed that would not be practical with either media alone.
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    A Network Communication Protocol for Distributed Virtual Environment Systems
    (Georgia Institute of Technology, 1996) Kessler, Gregory Drew ; Hodges, Larry F. ; GVU Center
    Virtual environment (VE) applications involve many different tasks, including interfacing with input and output devices, providing responsive user interaction, and simulating a dynamic environment. The variety and number of tasks lends the application to a distributed computing system, where different tasks are performed by different computing resources. A critical issue that arises from such a design is how information is communicated between tasks. In particular, for virtual environments, how information is communicated promptly is the critical issue. In this work, we describe a pattern of communication common between VE tasks which is not addressed by other communication protocols, namely the communication of state information that continuously changes. We describe a new protocol based on an updatable queue abstraction which allows obsolete state information to be discarded, and compare a prototype implementation of that abstraction with a standard communication protocol.
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    Effectiveness of Peripheral Level of Detail Degradation When Used with Head-Mounted Displays
    (Georgia Institute of Technology, 1996) Watson, Benjamin A. (Benjamin Allen) ; Walker, Neff ; Hodges, Larry F. ; Worden, Aileen ; GVU Center
    Two user studies were performed to evaluate the effectiveness of level of detail (LOD) degradation in the periphery of head-mounted displays. In the first study, spatial detail was degraded by reducing resolution. In the second study, detail was degraded in the color domain by using grayscale in the periphery. In each study, ten subjects were given a complex search task that required users to indicate whether or not a target object was present among distractors. Subjects used several different displays varying in the amount of detail presented. Frame rate, object location, subject input method, and order of display use were all controlled. Primary dependent measures were search time on correctly performed trials, and the percentage of all trials correctly performed. Results indicated that peripheral LOD degradation can be used to reduce visual complexity by almost half without hurting performance. Users were more sensitive to decreases in LOD than increases in degraded display area.
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    A Simple Yet Robust Caching Algorithm Based on Dynamic Access Patterns
    (Georgia Institute of Technology, 1994) Pitkow, James Edward ; Recker, Mimi ; GVU Center
    The World Wide Web continues its remarkable and seemingly unregulated growth. This growth has seen a corresponding increase in network loads and user response times. One common approach for improving the retrieval rate of large, distributed documents is via caching. In this paper, we present a caching algorithm that flexibly adapt its parameters to the hit rates and access patterns of users requesting documents. The algorithm is derived from an analysis of user accesses in a WWW database. In particular, the analysis is based upon a model from psychological research on human memory, which has long studied retrieval of memory items based on frequency and recency rates of past item occurrences. Results show that the model predicts document access with a high degree of accuracy. Furthermore, the model indicates that a caching algorithm based upon the recency rates of prior document access will reliably handle future document requests. The algorithm presented is simple, robust, and easily implementable.
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    Finger Sculpting with Digital Clay: 3D Shape Input and Output through a Computer-Controlled Real Surface
    (Georgia Institute of Technology, 2003) Book, Wayne J. ; Glezer, Ari ; Ebert-Uphoff, Imme ; Shaw, Christopher D. ; Rossignac, Jarek ; Allen, Mark G. ; Rosen, David W. ; Askins, Stephen Alexander ; Bai, Jing ; Bosscher, Paul Michael ; Gargus, Joshua ; Kim, Byungmoon ; Llamas, Ignacio ; Nguyen, Austina Nga ; Yuan, Guang ; Zhu, Haihong ; GVU Center
    The NSF Digital Clay project is focused on the design, prototyping, integration, and validation of a computer-controlled physical device capable of taking any of a wide range of possible shapes in response to changes in a digital 3D model or to changes in the pressure exercised upon it by human hands. Although it clearly is a natural and unavoidable evolution of 3D graphical user interfaces, its unprecedented capabilities constitute a major leap in technologies and paradigms for 3D display, for 3D input, and for collaborative 3D design. In this paper, we provide an overview of the Digital Clay project and discuss the challenges, design choices, and initial solutions for a new Finger Sculpting interface designed for the Digital Clay and prototyped using conventional 3D I/O hardware.
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    Glyphmaker: An Interactive, Programmerless Approach for Customizing, Exploring, and Analyzing Visual Data Representations
    (Georgia Institute of Technology, 1993) Ribarsky, William ; Tumblin, John Erwin (Jack) ; Newton, Gregory P. ; Nowicki, Robert ; Vetter, Jeffrey Scott ; GVU Center
    Glyphmaker is an interactive system for data visualization and analysis that is built in a dataflow environment. Glyphmaker provides a quite general platform for user-defined visualizations, one that can be extended in many ways and that, in particular, offers the first stage for an integrated visualization/analysis system. It is well-suited for the exploration and analysis of multivariate, highly correlated 3D data, which is increasingly the form of modern data. This is both because of the glyph-based visual representations and the interactivity that are built into the system. To summarize its capabilities, Glyphmaker allows the user to: (a) design glyphs by assembling them from different shapes; (b) choose binding sites on these shapes; (c) bind user data attributes to glyph elements; (d) conditionally isolate certain variable ranges; (e) interactively view, explore, remove, or rebind the resulting glyph sets as solid 3D objects. Each of these capabilities has a graphical user interface and is built into Glyphmaker in a modular form. The Glyphmaker approach of arranging data into data objects that are then bound to 3D graphical objects (glyphs) or manipulated by interactive tools is quite extensible in terms of visual representations and analysis methods.
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    Investigating Multimedia Learning with Web Lectures
    (Georgia Institute of Technology, 2006) Day, Jason Allan ; Foley, James D. ; Catrambone, Richard ; GVU Center
    Naturalistic research has shown that a web lecture intervention that includes multimedia lectures studied before class, short homework assignments, and in-class application activities can increase students' grades and satisfaction. The multimedia lectures, called web lectures, are a combination of video, audio, and PowerPoint streamed over the web. This experimental study was motivated by a desire to understand the contribution of web lectures themselves to the web lecture intervention's success. Educational multimedia design guidelines from Cognitive Load Theory (CLT) and the Cognitive Theory of Multimedia Learning (CTML) were used to evaluate and hypothesize about the learning efficacy of three information-equivalent-Video+Audio+PPT (web lecture), Audio+PPT, PPT+Transcript-and one information-nonequivalent-PPT-Only-educational presentation conditions. 60 randomly assigned participants studied the educational materials and completed a posttest and exit survey. Participants in the web lecture condition performed statistically significantly better on the posttest than all other conditions, and survey responses indicated that participants perceived the combination of modalities used by web lectures as more educationally effective than those used in the other conditions. This study verifies the educational contribution of web lectures to the web lecture intervention, web lectures' educational effectiveness as standalone learning objects, and the value-added of video for educational multimedia. These results were not completely in line with our hypothesis based on CLT and CTML, suggesting these theories' limited applicability for multimedia presentations with characteristics of those used in this study. Several possible factors that might account for the results inconsistent with CLT and CTML are identified, including the visibility of gesture in the video and the length and subject matter of the presentations.