Computer Science
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Item The Design of History Mechanisms and their Use in Collaborative Educational Simulations(1999-08-25) Plaisant, Catherine; Rose, Anne; Rubloff, Gary; Salter, Richard; Shneiderman, BenReviewing past events has been useful in many domains. Videotapes and flight data recorders provide nvaluable technological help to sports coaches or aviation engineers. Similarly, providing learners with a readable recording of their actions may help them monitor their behavior, reflect on their progress, and experiment with revisions of their experiences. It may also facilitate active collaboration among dispersed learning communities. Learning histories can help students and professionals make more effective use of digital library searching, word processing tasks, computer-assisted design tools, electronic performance support systems, and web navigation. This paper describes the design space and discusses the challenges of implementing learning histories. It presents guidelines for creating effective implementations, and the design tradeoffs between sparse and dense history records. The paper also presents a first implementation of learning histories for a simulation-based engineering learning environment called SimPLE (Simulated Processes in a Learning Environment) for the case of a semiconductor fabrication module, and reports on early user evaluation of learning histories implemented within SimPLE. Also cross-referenced as UMIACS-TR-99-34Item Excentric Labeling: Dynamic Neighborhood Labeling for Data Visualization(1998-11-04) Fekete, Jean-Daniel; Plaisant, CatherineThe widespread use of information visualization is hampered by the lack of effective labeling techniques. A taxonomy of labeling methods is proposed. We then describe "excentric labeling", a new dynamic technique to label a neighborhood of objects located around the cursor. This technique does not intrude into the existing interaction, it is not computationally intensive, and was easily applied to several visualization applications. A pilot study indicates a strong speed benefit for tasks that involve the rapid exploration of large numbers of objects. Also cross-referenced as UMIACS-TR-98-59Item LifeLines: Using Visualization to Enhance Navigation and Analysis of Patient Records(1998-11-12) Plaisant, Catherine; Mushlin, Richard; Snyder, Aaron; Li, Jia; Heller, Dan; Shneiderman, BenLifeLines provide a general visualization environment for personal histories. We explore its use for clinical patient records. A Java user interface is described, which presents a one-screen overview of a computerized patient record using timelines. Problems, diagnoses, test results or medications can be represented as dots or horizontal lines. Zooming provides more details; line color and thickness illustrate relationships or significance. The visual display acts as a giant menu, giving direct access to the data. (Also cross-referenced as UMIACS-TR-98-56)Item Interfaces and Tools for the Library of Congress National Digital Library(1998-10-15) Marchionini, Gary; Plaisant, Catherine; Komlodi, AnitaThis paper describes a collaborative effort to explore user needs in a digital library, develop interface prototypes for a digital library, and suggest and prototype tools for digital librarians and users at the Library of Congress (LC). Interfaces were guided by an assessment of user needs and aimed to maximize interaction with primary resources and support both browsing and analytical search strategies. Tools to aid users and librarians in overviewing collections, previewing objects, and gatherin g results were created and serve as the beginnings of a digital librarian toolkit. The design process and results are described and suggestions for future work are offered. (Also cross-referenced as UMIACS-TR-98-09)Item The End of Zero-Hit Queries: Query Previews for NASA's Global Change Master Directory(1998-10-15) Greene, Stephan; Tanin, Egemen; Plaisant, Catherine; Shneiderman, Ben; Olsen, Lola; Major, Gene; Johns, SteveThe Human-Computer Interaction Laboratory (HCIL) of the University of Maryland and NASA have collaborated over the last three years to refine and apply user interface research concepts developed at HCIL in order to improve the usability of NASA data services. The research focused on dynamic query user interfaces, visualization, and overview +preview designs. An operational prototype, using query previews, was implemented with NASA's Global Change Master Directory (GCMD), a directory service for earth science data sets. Users can see the histogram of the data distribution over several attributes and choose among attribute values. A result bar shows the cardinality of the result set, thereby preventing users from submitting queries that would have zero hits. Our experience confirmed the importance of metadata accuracy and completeness. The query preview interfaces make visible problems or holes in the metadata that are unnoticeable with classic form fill-in interfaces. This could be seen as a problem, but we think that it will have a long-term beneficial effect on the quality of the metadata as data providers will be compelled to produce more complete and accurate metadata. The adaptation of the research prototype to the NASA data required revised data structures and algorithms. (Also cross-referenced as UMIACS-TR-97-84)Item An Information Architecture to Support the Visualization of Personal Histories(1998-10-15) Plaisant, Catherine; Shneiderman, BenAlso cross-referenced as UMIACS-TR-97-87Item Previews and Overviews in Digital Libraries: Designing Surrogates to Support Visual Information Seeking(1998-11-03) Greene, Stephan; Marchionini, Gary; Plaisant, Catherine; Shneiderman, BenTo aid designers of digital library interfaces and web sites in creating comprehensible, predictable and controllable environments for their users, we define and discuss the benefits of previews and overviews as visual information representations. Previews and overviews are graphic or textual representations of information abstracted from primary information objects. They serve as surrogates for those objects. When utilized properly, previews and overviews allow users to rapidly discriminate objects of interest from those not of interest, and to more fully understand the scope and nature of large collections of information resources. We provide a more complete definition of previews and overviews, and discuss system parameters and aspects of primary information objects relevant to designing effective preview and overviews. Finally, we present examples that illustrate the use of previews and overviews and offer suggestions for designers. (Also cross-referenced as UMIACS-TR-97-73)Item Visualizing websites using a hierarchical table of contents browser: WebTOC(1998-11-20) Nation, David A.; Plaisant, Catherine; Marchionini, Gary; Komlodi, AnitaA method is described for visualizing the contents of a Web site with a hierarchical table of contents using a Java program and applet called WebTOC. The automatically generated expand/contract table of contents provides graphical information indicating the number of elements in branches of the hierarchy as well as individual and cumulative sizes. Color can be used to represent another attribute such as file type and provide a rich overview of the site for users and managers of the site. Early results from user studies suggest that WebTOC is easily learned and can assist users in navigating websites. (Also cross-referenced as UMIACS-TR-97-41)Item Understanding Transportation Management Systems Performance with a Simulation-Based Learning Environment(1998-12-05) Plaisant, Catherine; Tarnoff, Phil; Saraf, Aditya; Rose, AnneWe have developed a simulation-based learning environment to provide system designers and operators with an appreciation of the impact of incidents on traffic delay. We used an application framework developed at the University of Maryland for constructing simulation-based learning environments called SimPLE (Simulated Processes in a Learning Environment). Environments developed with SimPLE use dynamic simulations and visualizations to represent realistic time-dependent behavior and are coupled with guidance material and other software aids that facilitate learning. The simulation allows learners to close freeway lanes and divert traffic to an arterial road. Users can see the effect of the detour on freeway and arterial delay. Users can then adjust signal timing interactively on a time space diagram and watch the effect of their adjustment on green band changes and on arterial delays and total delays.Item Data Object and Label Placement For Information Abundant Visualizations(1998-12-08) Li, Jia; Plaisant, Catherine; Shneiderman, BenPlacing numerous data objects and their corresponding labels in limited screen space is a challenging problem in information visualization systems. Extending map-oriented techniques, this paper describes static placement algorithms and develops metrics (such as compactness and labeling rate) as a basis for comparison among these algorithms. A control panel facilitates user customization by showing the metrics for alternative algorithms. Dynamic placement techniques that go beyond map-oriented techniques demonstrate additional possibilities. User actions can lead to selective display of data objects and their labels.