Hierarchical Data Visualization in Desktop Virtual Reality
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Hierarchical Data Visualization In Desktop Virtual Reality by David K. Modjeska A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Computer Science University of Toronto © Copyright by David Modjeska 2000 Hierarchical Data Visualization in Desktop Virtual Reality by David K. Modjeska Ph.D. Thesis Department of Computer Science University of Toronto 2000 Abstract While desktop virtual reality (VR) offers a way to visualize structure in large information sets, there have been relatively few empirical investigations of visualization designs in this domain. This thesis reports the development and testing of a series of prototype desktop VR worlds, which were designed to support navigation during information visualization and retrieval. Four methods were used for data collection: search task scoring, subjective questionnaires, navigational activity logging and analysis, and administra- tion of tests for spatial and structure-learning ability. The combination of these research methods revealed significant effects of user abilities, information environment designs, and task learning. The first of four studies compared three versions of a structured virtual landscape, finding significant dif- ferences in sense of presence, ease of use, and overall enjoyment; there was, however, no significant difference in performance among the three landscape versions. The second study found a hypertext inter- face to be superior to a VR interface for task performance, ease of use, and rated efficiency; nevertheless, the VR interface was rated as more enjoyable. The third study used a new layout algorithm; the resulting prototype was rated as easier to use and more efficient than the previous VR version. In the fourth study, a zoomable, map-like view of the newest VR prototype was developed. Experimental participants found the map-view superior to the 3D-view for task performance and rated efficiency. Overall, this research did not find a performance advantage for using 3D versions of VR. In addition, the results of the fourth study found that people in the lowest quartile of spatial ability had significantly lower search performance (relative to the highest three quartiles) in a VR world. This finding suggests that indi- vidual differences for traits such as spatial ability may be important in determining the usability and acceptability of VR environments. In addition to the experimental results summarized above, this thesis also developed and refined a meth- odology for investigating tasks, users, and software in 3D environments. This methodology included tests for spatial and structure-learning abilities, as well as logging and analysis of a user’s navigational activi- ties. ii Acknowledgements This research was made possible through funding from the Department of Computer Science at the Uni- versity of Toronto. Please note that aspects of the present research have been published previously (Modjeska, 1998; Modjeska, 1999; Modjeska and Waterworth, 2000). For design contributions to the research prototypes, I would like to thank Walter Frost and Russell Kroll, formerly of the Institute of Design at Umeå University. For first implementation of the research proto- types, I would like to thank Karel Moijson and David Steeman, formerly of the Hogeschool Gent. For questions, advice, and support, I would like to thank the Interactive Media Lab in the Department of Mechanical and Industrial Engineering at the University of Toronto. For encouraging my research interests and progress at a critical point, I would like to thank a former co- supervisor, Marilyn Mantei. For contributions of expertise and perspective, I would like to thank the members of my thesis committee: Alberto Mendelzon, and Michiel van de Panne. For supervision and inspiration, I would like to thank my guest supervisor, John Waterworth, in the De- partment of Informatics at Umeå University. The Informatics department as a whole contributed comments, companionship, and advice. For weekly conversations about the meaning and implications of this research, I would like to thank my co-supervisor, monica schraefel. For patience, supervision, and wit, I would like to thank my supervisor, Mark Chignell. His role in launching and completing this research, and developing opportunities for future work, has been central. Finally, I’d like to thank my wife, Natalia Nygren Modjeska, for patience, inspiration, encouragement, and support during the final years of research. iii Table of Contents Abstract . ii Acknowledgements . iii Table of Contents . iv List of Tables . viii List of Figures . ix List of Appendices . .xii 1. Introduction . 1 1.1. Research Context . .1 1.2. Research Questions . 2 1.3. Thesis Perspective and Organization . 7 2. Related Research . 8 2.1. Introduction . 8 2.2. Cognitive Engineering and UI Metaphors . 9 2.3. Information Structuring . .11 2.3.1. Semantic vs. Physical Models . 11 2.3.2. Structure Types . 12 2.3.3. Hierarchical Structures . 14 2.3.4. Experimental Results . .16 2.3.5. Designs for Hypermedia and Spatial Worlds . 17 2.3.6. Discussion . 19 2.4. Physical and Information Exploration . 20 2.4.1. General Models . .20 2.4.2. Mental Maps . 22 2.4.3. Wayfinding . 26 2.4.4. Hypermedia Environments . 33 2.4.5. Spatial Ability in Electronic Environments . 37 2.4.6. Discussion . .41 2.5. Information Visualization . 41 2.5.1. Fisheye Views . .42 2.5.2. Semantic Zooming . 43 2.5.3. Cone Tree, Hyperbolic Browser, and Butterfly . 45 2.5.4. Visualization for Information Retrieval . 48 iv 2.5.5. Spaces for Public Information . 50 2.5.6. Visualizing Hypermedia Structure . 53 2.5.7. Discussion . .58 2.6. Summary . 59 2.7. Conclusions . 60 3. Study 1 – Day, Dusk, and Night Worlds . 62 3.1. Introduction . 62 3.2. Methodology . 62 3.2.1. Apparatus . 63 3.2.1.1. Description . 63 3.2.1.2. Development . 66 3.2.2. Procedure . 67 3.2.3. Measures . .68 3.3. Results . 69 3.3.1. Description . 69 3.3.2. Underlying Factors of Performance . 70 3.3.3. Effects on User Strategy . 72 3.3.4. Learning Effects within Blocks . 73 3.3.5. Experimental Control . 74 3.4. Conclusions . 74 4. Study 2 – VR vs. Hypertext . 76 4.1. Introduction . 76 4.2. Methodology . 77 4.2.1. Apparatus . 77 4.2.2. Procedure . 77 4.2.3. Measures . .79 4.3. Results . 80 4.3.1. Description . ..