This paper explores the link between users' physical navigation, specifically their distance from their current object(s) of focus, and their interaction scale. We define a new 3D interaction technique, called multiscale interaction, which links users' scale of perception and their scale of interaction. The technique exploits users' physical navigation in the 3D space in front of a large highresolution display, using it to explicitly control scale of interaction, in addition to scale of perception. Other interaction techniques for large displays have not previously considered physical navigation to this degree. We identify the design space of the technique, which other researchers can continue to explore and build on, and evaluate one implementation of multiscale interaction to begin to quantify the benefits of the technique. We show evidence of a natural psychological link between scale of perception and scale of interaction and that exploiting it as an explicit control in the user interface can be beneficial to users in problem solving tasks. In addition, we show that designing against this philosophy can be detrimental. KEYWORDS: interaction technique, large tiled display, physical navigation INDEX TERMS: H.5.2 User Interfaces -Interaction styles The decreasing price of displays has enabled the exploration of ever-larger and higher-resolution displays. Previous research has quantified benefits from both the increased size and the increased resolution. Several studies have shown that with large datasets, such as those found in geospatial analysis, the larger viewport size improves users' performance time and decreases frustration [1, 14] . A key benefit of large high-resolution displays is that they afford greater opportunity for physical navigation (moving one's body to navigate the displayed information). These studies found a correlation between faster user performance time, a decrease in virtual navigation and an increase in physical navigation. Evidence indicated that physical navigation was more efficient, effective, and preferred than virtual navigation. While increasing display size has significant benefits for user performance, it also creates a new difficulty -how do users interact with it? In particular, given that users physically navigate when using large display information spaces, how should that affect the design of interaction techniques? Stationary interaction devices, such as the traditional keyboard and mouse, can tether users and discourage physical navigation. Considering 3D input (such as tracking head, hand or body movement) for interaction with large 2D displays offers new possibilities for interface design that supports physical navigation [12] . However, when physically navigating, users move in and out from the display to zoom into details or out for an overview, essentially changing the scale at which they perceive the information. Untethered interaction techniques can enable users to interact with the display from anywhere as they move around in the space in front of the display, but this interaction is static. During physical navigation, users' visual scale changes, but their scale of interaction does not change. This is a problem because users often do different types of tasks at different levels of visual scale. As they step out to see an overview, they are still interacting with it on the detail level, even though they are no longer able to see any of the details. Introducing additional controls that enable users to change the scale of interaction can cause extra confusion, visual and interactive clutter, and difficulties with accuracy, analogous to virtual navigation. There is evidence that people naturally interact on different levels of scale in the literature on pointing. People can indicate a single nearby object by pointing alone. However, people either refer to faraway areas only, or compensate for the ambiguity brought on by distance by adding verbal descriptions [8, 11] . This change in how people point to a target based on their distance from it can be modeled approximately by a cone extending out from the finger, representing the degree of pointing accuracy with which people perceive they are pointing [8] . Thus, two related behaviors have been demonstrated: people move to perceive varying levels of scale, and people point at varying degrees of detail according to distance. Is it possible to combine these behaviors to provide an efficient and explicit multiscale pointing capability on large displays? Can physical navigation be exploited, using it as an explicit operator to control the scale level of interaction, in addition to perception? We suggest a class of interaction techniques, called multiscale interaction, which links the two behaviors by changing the user's scale of interaction depending on their distance from the current object(s) of interaction. To demonstrate this, we implemented a 3D interaction technique [2] that automatically changes the scale of a 2D cursor according to the user's distance from the display, using a 3D input device to interact directly with a large 2D information space on the display, as seen in Figure 1 . This paper first describes the design space for multiscale interaction, and the benefits we believe can be derived from it. Second, it discusses a {*speck, † north, ‡
Multiscale interaction by Peck et al. REF ) is a 3D interaction technique that uses the benefit of physical navigation in front of a large high-resolution display.
A multiscale interaction technique for large, high-resolution displays
2009 IEEE Symposium on 3D User Interfaces
2009 IEEE Symposium on 3D User Interfaces
Computer Science