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Stasko, John T.

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End date: 1999 × Start date: 1991 × search.filters.applied.f.resourcesubtype: Technical Report ×

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Exploring Animation as a Presentation Technique for Dynamic Information Sources

1999 , McCrickard, D. Scott , Stasko, John T. , Zhao, Qiang Alex

The constantly growing and changing nature of certain information sources creates new problems in presenting it to the user. While it may be desirable to maintain awareness of changes to this information, it is typically not a person's primary task. This article describes how animation can be used to communicate dynamic information in a limited space and with limited disruption to the user. We focus on a study on the preferences and reactions of twenty-five participants to tkscore, an application that presents NCAA Tournament game scores using a variety of different animated displays. Results from the study are provided along with future research directions.

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Multimedia support for introductory and advanced computer science education

1998 , Stasko, John T.

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The Information Mural: A Technique for Displaying and Navigating Large Information Spaces

1997 , Jerding, Dean Frederick , Stasko, John T.

Information visualizations must allow users to browse information spaces and focus quickly on items of interest. Being able to see some representation of the entire information space provides an initial gestalt overview and gives context to support browsing and search tasks. However, the limited number of pixels on the screen constrain the information bandwidth and make it difficult to completely display large information spaces. The Information Mural is a two-dimensional, reduced representation of an entire information space that fits entirely within a display window or screen. The mural creates a miniature version of the information space using visual attributes such as grayscale shading, intensity, color, and pixel size, along with anti-aliased compression techniques. Information Murals can be used as stand-alone visualizations or in global navigational views. We have built several prototypes to demonstrate the use of Information Murals in visualization applications; subject matter for these views includes computer software, scientific data, text documents, and geographic information.

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The Information Mural: Increasing Information Bandwidth in Visualizations

1996 , Jerding, Dean Frederick , Stasko, John T.

Information visualizations must allow users to browse information spaces and focus quickly on items of interest. Being able to see some representation of the entire information space provides an initial gestalt overview and gives context to support browsing and search tasks. However, the limited number of pixels on the screen constrain the information bandwidth and make it difficult to completely display large information spaces. The Information Mural is a two-dimensional, reduced representation of an entire information space that fits entirely within a display window or screen. The mural creates a miniature version of the information space using visual attributes such as grayscale shading, intensity, color, and pixel size, along with anti-aliased compression techniques. Information Murals can be used as stand-alone visualizations or in global navigational views. We have built several prototypes to demonstrate the use of Information Murals in visualization applications; subject matter for these views includes computer software, scientific data, text documents, and geographic information.

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Rethinking the Evaluation of Algorithm Animations as Learning Aids: An Observational Study

1999 , Kehoe, Colleen Mary , Stasko, John T. , Taylor, Ashley

A number of prior studies have found that using animation to help teach algorithms had less beneficial effects on learning than hoped. Those results surprise many computer science instructors whose intuition leads them to believe that algorithm animations should assist instruction. This article reports on a study in which animation is utilized in more of a "homework" learning scenario rather than a "final exam" scenario. Our focus is on understanding how learners will utilize animation and other instructional materials in trying to understand a new algorithm, and on gaining insight into how animations can fit into successful learning strategies. The study indicates that students use sophisticated combinations of instructional materials in learning scenarios. In particular, the presence of algorithm animations seems to make a challenging algorithm more accessible and less intimidating, thus leading to enhanced student interaction with the materials and facilitating learning.

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PML: Representing Procedural Domains for Multimedia Presentations

1998 , Ram, Ashwin , Catrambone, Richard , Guzdial, Mark , Kehoe, Colleen Mary , McCrickard, D. Scott , Stasko, John T.

A central issue in the development of multimedia systems is the presentation of the information to the user of the system and how to best represent that information to the designer of the system. Typically, the designers create a system in which content and presentation are inseparably linked; specific presentations and navigational aids are chosen for each piece of content and hard-coded into the system. We argue that the representation of content should be decoupled from the design of the presentation and navigational structure, both to facilitate modular system design and to permit the construction of dynamic multimedia systems that can determine appropriate presentations in a given situation on the fly. We propose a new markup language called PML (Procedural Markup Language) which allows the content to be represented in a flexible manner by specifying the knowledge structures, the underlying physical media, and the relationships between them using cognitive media roles. The PML description can then be translated into different presentations depending on such factors as the context, goals, presentation preferences, and expertise of the user.

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Using Student-Built Algorithm Animations as a Learning Aid

1996 , Stasko, John T.

The typical application of algorithm animation to assist instruction involves students viewing already prepared animations. An alternative strategy is to have the students themselves construct animations of algorithms. The Samba algorithm animation tool fosters such student-built animations. Samba was used in an undergraduate algorithms course in which students constructed algorithm animations as regular class assignments. This article describes Samba and documents our experiences using it in the algorithms course. Student reaction to the animation assignments was very positive, and the students appeared to learn the pertinent algorithms extremely well.

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The Awareness-Privacy Tradeoff in Video Supported Informal Awareness: A Study of Image-Filtering Based Techniques

1998 , Zhao, Qiang Alex , Stasko, John T.

Media space applications that promote informal awareness in an organization confront an inevitable paradox: the shared video connections between offices and rooms that promote informal awareness also can rob individuals of privacy. An important open problem in this area is how to foster awareness of colleagues without the accompanying loss of privacy. One proposal put forward is to filter the communicated video streams rather than broadcasting clear video. In this article, we describe several image-filtering techniques that may provide awareness in informal group communication applications while blurring the details of an individuals activities, thus potentially preserving more privacy. We describe experiments to quantitatively and qualitatively assess the degrees of awareness and accuracy that these filtering techniques provide.

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Robust State Sharing for Wide Area Distributed Applications

1997 , Topol, Brad Byer , Ahamad, Mustaque , Stasko, John T.

In this article, we present the Mocha wide area computing infrastructure we are currently developing. Mocha provides support for robust shared objects on heterogeneous platforms, and utilizes advanced distributed shared memory techniques for maintaining consistency of shared objects that are replicated at multiple nodes to improve performance. In addition, our system handles failures that we feel will be common in wide area environments. For example, to ensure that the state of an object is not lost due to a node failure, updated state of the object can be disseminated to several other nodes. The overhead of such state dissemination can be controlled based on the level of availability needed for shared objects. We have used an approach that makes use of multiple communication protocols to improve the efficiency of shared object state transfers in Mocha. We also provide an empirical evaluation of our prototype implementation for both local and wide area networks and present a sample home service application written with the system.

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Monitoring and Visualization in Cluster Environments

1996 , Topol, Brad Byer , Stasko, John T. , Sunderam, Vaidy

Cluster computing has evolved into a popular and effective mode of high performance computing. Cluster environments are intrinsically different from hardware multiprocessors, and hence require a different approach to measuring and characterizing performance, monitoring an application's progress, and understanding program behavior. In this article, we present the design and implementation of PVaniM, an experimental visualization environment we have developed for the PVM network computing system. PVaniM supports a two-phase approach whereby on-line visualization focuses on large-grained events that are influenced by and relate to the dynamic cluster environment, and postmortem visualization provides for detailed program analysis and tuning. PVaniM's capabilities are illustrated via its use on several applications and it is compared with other visualization environments developed for cluster computing. Our experiences indicate that for several classes of applications, the two-phase visualization scheme can provide more insight into the behavior, efficiency, and operation of distributed and parallel programs in cluster environments.

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