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Sizing Up Visualizations: Effects of Display Size in Focus+Context, Overview+Detail, and Zooming Interfaces Mikkel Rønne Jakobsen & Kasper Hornbæk Department of Computer Science, University of Copenhagen, Denmark mikkelrj@diku.dk, kash@diku.dk ABSTRACT Whereas the literature is clear on the benefits of large displays and visualizations, little is known about their combination, that is, how display size affect the usability of visualizations. We describe a controlled experiment where 19 participants used focus+context, overview+detail, and zooming techniques with varying display sizes (13.8, 1.5, and 0.17 megapixels). Participants navigated geographical maps to find specific locations, compare items, and follow routes. Results show that for multi-scale navigation, classic interactive visualization techniques did not benefit from being scaled to a large display: In contrast to the literature we find similar performance on medium and large displays. Across display sizes, overview+detail works the best, in particular for comparing items. Focus+context is relatively more difficult to use at a small display size. We explain these findings and discuss the design of interactive visualization techniques for large displays. Author Keywords Large high-resolution displays, information visualization, multi-scale navigation, user study ACM Classification Keywords H.5.2 [Information interfaces and presentation]: User Interfaces—Graphical user interfaces (GUI) General Terms Experimentation, Human Factors INTRODUCTION Interactive visualization techniques aim to help users navigate large information spaces that do not fit within the display. However, their usability has mostly been investigated for a narrow range of display size (roughly corresponding to Figure 1, b). Meanwhile, the range of display sizes in common use is increasing, from mobile devices to large high-resolution displays. This paper investigates how classic interactive visualization techniques perform with larger and smaller displays (Figure 1, a and c). Large high-resolution displays allow more information to be shown at a time, and have been found to improve task performance and user satisfaction [e.g., 14, 35]. Similarly, visualization techniques have been shown useful for many tasks [e.g., 11, 13]. The combination of large displays and visualizations, however, raises new questions: Can we expect the performance gains of visualization approaches for smaller displays [10] to scale to large displays? Does the finding that overview+detail visualizations improve task completion time and satisfaction [13] hold on displays with enough pixels to give an overview? Which tasks are most effectively solved with visualizations on a large display? North and colleagues have given answers to some of these types of question [1, 3, 36, 37]. They have shown how physical navigation improves performance on large displays and that comparison of visualizations’ performance gives similar results across display sizes. However, they have argued that questions about what happens when “the data/pixel count scales up” and how “different navigation strategies, such as overview+detail, and focus+context, affect high resolution visualization” remain unanswered [3]. This paper contributes empirical data on the effect of display size on the usability of visualization techniques for navigating multi-scale information spaces. We investigate three classic interactive visualization techniques (focus+context, overview+detail, and zooming), using tasks and data similar to previous studies. In contrast to most work by North and colleagues, we investigate interactive visualizations and look at their usability for navigating the same, large information space. In contrast to work on visualization for small displays [e.g., 10], we compare across all display sizes of Figure 1. The intended benefit of this line of work is to understand better how to design and adapt visualizations for small and large displays. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. CHI 2011, May 7–12, 2011, Vancouver, BC, Canada. Copyright 2011 ACM 978-1-4503-0267-8/11/05....$10.00. Figure 1: How do visualization techniques perform at different display sizes such as (a) 13.8, (b) 1.5, or (c) 0.17 megapixels? CHI 2011 • Session: Visualization & Perception May 7-12, 2011 • Vancouver, BC, Canada1451