Person:

Stasko, John T.

Permanent Link

https://hdl.handle.net/1853/71735

Associated Organization(s)

Organizational Unit

School of Interactive Computing

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Publication Search Results

Now showing 1 - 10 of 31

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

(Georgia Institute of Technology, 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.
Multimedia support for introductory and advanced computer science education

(Georgia Institute of Technology, 1998) Stasko, John T.
PML: Representing Procedural Domains for Multimedia Presentations

(Georgia Institute of Technology, 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.
Robust State Sharing for Wide Area Distributed Applications

(Georgia Institute of Technology, 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.
The Information Mural: A Technique for Displaying and Navigating Large Information Spaces

(Georgia Institute of Technology, 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.
Using Student-Built Algorithm Animations as a Learning Aid

(Georgia Institute of Technology, 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.
Monitoring and Visualization in Cluster Environments

(Georgia Institute of Technology, 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.
The Information Mural: Increasing Information Bandwidth in Visualizations

(Georgia Institute of Technology, 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.
Visualizing Message Patterns in Object-Oriented Program Executions

(Georgia Institute of Technology, 1996) Jerding, Dean Frederick ; Stasko, John T. ; Ball, Thomas (Thomas Jaudon)

The dynamic behavior of object-oriented programs is difficult to design, implement, and modify. Understanding the interactions between classes and objects is necessary to create efficient designs and make safe modifications. This work seeks to identify, visualize, and analyze recurring message patterns in object-oriented program executions as a means for understanding and examining dynamic behavior. Our visualizations focus on supporting design recovery, validation, and reengineering tasks.
Do Algorithm Animations Aid Learning?

(Georgia Institute of Technology, 1996) Byrne, Michael Dwyer ; Catrambone, Richard ; Stasko, John T.

Two experiments examined the general claim that animations can help students learn algorithms more effectively. Animations and instructions that explicitly required learners to predict the behavior of an algorithm were used during training. Post-test problems were designed to measure how well learners could predict algorithm behavior in new situations as well as measure learners' conceptual understanding of the algorithms. In Experiment 1, we found that when learners both viewed an animation and made predictions, their performance on novel problems improved comapred to a control group's, but the effects of the two manipulations were not distinguishable. In Experiment 2, no effect was found for conceptual measures of learning, but a marginally reliable effect similar to the one seen in Experiment 1 was found for procedural problems. The results from the two experiments suggest that the benefits of animations are not obvious and that in order to determine whether animations can truly aid understanding, teachers and researchers should consider a careful task analysis ahead of time to determine the specific pieces of knowledge that an animation can help a learner acquire and/or practice.