UFO-Zoom: A new coupled map navigation technique using hand trajectories in the air Bora Kang, Eunjung Choi, Sunghyuk Kwon, Min K. Chung * Dept. of Industrial and Management Engineering, Pohang University of Science & Technology, San 31, Hyoja-dong, Nam gu, Pohang, 790-784 Gyeongbuk, Republic of Korea article info Article history: Received 24 June 2012 Received in revised form 26 September 2012 Accepted 30 October 2012 Available online 4 December 2012 Keywords: Panning Zooming Map navigation Hand gesture UFO-Zoom Usability abstract This study proposed a new map navigation technique ‘UFO-Zoom’ that uses trajectories of the finger in the air. UFO-Zoom was developed to provide users complete freedom for panning and zooming opera- tions. Zooming is controlled by the vertical distance between the screen and the users’ fingertip; panning is controlled by finger movements parallel to the screen. Because these operations are not totally coupled, the users are totally free to change modes among panning only, zooming only, and coupled panning and zooming. A usability test was performed to compare UFO-Zoom with a simple ‘Pan-and- zoom’ method and ‘Speed-Dependent Automatic Zooming’ in three different map sizes. UFO-Zoom showed shorter task completion time, higher subjective ratings and lower workload than the other methods. Participants reported that UFO-Zoom was interesting, fast, easy to use and intuitive. Relevance to industry: The results of this study can be used to enhance the usability of map navigation technique when users navigate a large information space. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Touch-screen interfaces which are intuitive, direct, simple, and easy to use utilize space on the screen efficiently and are flexible in user interface design. For these reasons, they are widely used in various devices such as smart phones, tablet PCs, tabletop computers and Portable Media Players (Kim and Yi, 2006; Nam et al., 2008; Lee, 2010). On those devices many users use map applications to obtain information about specific regions or build- ings, to find routes between regions, or to estimate time and distance to a destination. Often, the target is off-screen; therefore, to find them, the users must use map navigating techniques which are basically composed of two functions ‘Pan’, which moves the area shown on a map, and ‘Zoom’, which enlarges or reduces the size of the area represented on the screen. Compared to navigating other small information spaces such as web pages, images, and short lists, navigating maps is significantly different in that zooming operations are frequently used because maps provide expansive and dense data on a wide range of scales (Kratz et al., 2010). Usually, the size of touch-screen interfaces is limited, so the amount of information presented on them is limited. This problem is more serious when information space is large. When users navigate relatively small information spaces, panning operations may be enough for effective and efficient navigation because a few panning operations can cover the entire information space. However, when information spaces are large, navigation requires frequent zooming operations as well as panning opera- tions. If zooming is not available, the number of panning operations needed to cover the entire map is too large and leads to a tedious and fatiguing user experience. A problem with scanning maps on a screen is that the users need to switch between panning and zooming modes; this switching may increase the users’ mental and physical loads (Kratz et al., 2010). Particularly, the mode-switching problem gets worse with direct input systems such as stylus or finger on the touch-screen interfaces on which we focus on in this study. This is because the stylus or finger is used for both panning and zooming in direct input systems, whereas a mouse has a special wheel for controlling zoom level (Fujita et al., 2010). Igarashi and Hinckley (2000) proposed ‘Speed-Dependent Automatic Zooming’ (SDAZ) as a navigation technique in which panning and zooming operations are coupled. In SDAZ, zoom level automatically decreases with increasing panning speed while keeping the visual flow of the information constant, thereby minimizing blurring effects. Some studies have reported that SDAZ reduced loads due to mode-switching and that SDAZ seemed to be an effective navigation method in usability tests (Cockburn and Savage, 2003; Cockburn et al., 2005; Jones et al., 2005). Fujita * Corresponding author. Tel.: þ82 54 279 2192; fax: þ82 54 279 2920. E-mail address: mkc@postech.ac.kr (M.K. Chung). Contents lists available at SciVerse ScienceDirect International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon 0169-8141/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ergon.2012.10.008 International Journal of Industrial Ergonomics 43 (2013) 62e69