Browsing by Author "Neumann, Petra"

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    Expressive Distortion of Strokes and 3D Meshes
    (2005-03-15) Neumann, Petra; Isenberg, Tobias; Carpendale, Sheelagh
    We introduce methods for applying two-dimensional distortions in a manner that allows us to create three-dimensional variations of stroke-based models and 3D polygonal meshes. These variations can be achieved interactively, supporting the creation of expressive variations of a given 3D model or of strokes generated from it. In order to allow for a seamless integration into existing systems and to enable additional processing of both strokes and meshes, a pipeline approach is taken in both cases. In addition, we discuss the interaction possibilities arising from the interplay between the model orientation and the strokes or the geometry. Finally, to demonstrate the usability of the proposed methods we suggest several application domains.
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    A Framework for Visual Information Analysis
    (2007-07-12) Neumann, Petra; Tang, Anthony; Carpendale, Sheelagh
    To design information visualization tools that support users needs, we need to understand how users engage with information visualizations in their analysis process. With the rapid growth in size and complexity of datasets, the practicality of an individual analyzing an entire dataset is becoming unrealistic. Instead, the expertise to make informed decisions about these information-rich datasets is often best accomplished by a team. However, there exist relatively few models that describe the visual analysis process, and only few studies that explore the differences between how individuals and teams use visualizations. We present an observational study where we explored the information analysis process of groups and individuals in the context of visual information. From the analysis of our study, we derive a framework that captures the activities of co-located teams and individuals engaged in information analysis. This framework has implications for the design, heuristic evaluation, and analysis of both collaborative and single-user digital information visualization tools.
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    Non-Photorealistic Rendering in Context: An Observational Study
    (2006-02-14) Isenberg, Tobias; Neumann, Petra; Carpendale, Sheelagh; Costa Sousa, Mario; Jorge, Joaquim A.
    Pen-and-ink line drawing techniques are frequently used to depict form, tone, and texture in artistic, technical, and scientific illustration. In non-photorealistic rendering (NPR), there has been considerable progress on reproducing traditional pen-and-ink techniques for rendering 3D objects. However, formal evaluation and validation of these NPR images remain an important open research problem. In this paper we present an observational study with three groups of users to examine their understanding and assessment of hand-drawn pen-and-ink illustrations of objects in comparison with NPR renditions of the same 3D objects. The results show that people perceive differences between those two types of illustration but that those that look computer-generated are still highly valued in terms of scientific illustration.
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    Taxonomy For Discrete Lenses
    (2003-12-17) Neumann, Petra; Carpendale, Sheelagh
    In this report we introduce new ways of thinking about different types of visual data distortion methods. In particular, we clarify terminology that can be used to distinguish between two visual distortion methods, discrete and continuous lenses. The set of presentation techniques that result from application of these distortion methods is extended by this exploration. We describe a theoretical framework for use in future research on these presentation techniques. This involves the exploration of general distortion effects and how these effects are utilized by the visualization tool designer. Finally, the usability of the concept of discrete lenses for developing new interaction techniques is demonstrated by example applications.