Characterizing user performance with assisted direct off-screen pointing

Abstract

The limited viewport size of mobile devices requires that users continuously acquire information that lies beyond the edge of the screen. Recent hardware solutions are capable of continually tracking a user"s finger around the device. This has created new opportunities for interactive solutions, such as direct off-screen pointing: the ability to directly point at objects that are outside the viewport. We empirically characterize user performance with direct offscreen pointing when assisted by target cues. We predict time and accuracy outcomes for direct off-screen pointing with existing and derived models. We validate the models with good results (R 2 ≥ 0.9) and reveal that direct off-screen pointing takes up to four times longer than pointing at visible targets, depending on the desired accuracy tradeoff. Pointing accuracy degrades logarithmically with target distance. We discuss design implications in the context of several real-world applications.

Around device interaction for multiscale navigation

“…The project explored 2D graffiti gestures, 2D visuospatial memory, and 2D pointing. Similarly, Ens et al explored user performance in 2D off-screen pointing [5]. In contrast to previous work, we are the first to tackle more complex 3D Around Device Interactions.…”

Comparing Direct Off-Screen Pointing, Peephole, and Flick & Pinch Interaction for Map Navigation

“…Accordingly, we were also interested in investigating how map navigation performance with the two spatial techniques is influenced by such on-screen guidance. Informed by earlier work [3,7], we opted for an overview visualization of the relevant map area with marker clusters and a blue circular position cursor that indicated what area of the map was currently displayed on the screen. All three techniques were tested with and without an onscreen overview.…”

“…For instance, Jones et al [8] demonstrate the potential of using in-air gestures instead of on-screen gestures to navigate within large workspaces. Ens et al [3] explore the concept of directly pointing into a virtual workspace that extends beyond the screen where items that reside outside the screen are selected by moving a finger to their corresponding in-air location. Ens et al present a performance model which captures this type of 'direct offscreen pointing' and show that user performance is largely dependent on on-screen guidance cues, such as a mini-map or an overview of the workspace.…”

Are you comfortable doing that?

“…Only a few projects have attended to the human factors involved when designing AD-interactions. Ens et al [2] modeled user performance in off-screen target acquisition tasks and Jones et al [7] examined user performance and preferences for multi-scale navigation in AD-space. Hasan et al [6] proposed a framework consisting of numerous design parameters relevant to AD-interactions, such as the range for user input, suitable in-air target sizes, selection methods and techniques for placing and retrieving content in AD-space.…”