Point-and-Shake

Abstract

Acoustic levitation enables a radical new type of humancomputer interface composed of small levitating objects. For the first time, we investigate the selection of such objects, an important part of interaction with a levitating object display. We present Point-and-Shake, a mid-air pointing interaction for selecting levitating objects, with feedback given through object movement. We describe the implementation of this technique and present two user studies that evaluate it. The first study found that users could accurately (96%) and quickly (4.1s) select objects by pointing at them. The second study found that users were able to accurately (95%) and quickly (3s) select occluded objects. These results show that Pointand-Shake is an effective way of initiating interaction with levitating object displays.

Levitating Particle Displays with Interactive Voxels

“…Each method has strengths and weaknesses that will affect their suitability for different user interfaces. For example, magnetic levitation allows just a single particle that users can physically grasp and reposition [12], whilst acoustic levitation allows several particles but users must interact with from a distance [7]. All share the properties that make levitating particle displays novel, however.…”

“…The most basic use of these voxels is to represent information through their relative position: for example, showing data with Floating Charts [22] or forming shapes in Pixie Dust [19]. Particles become more expressive when moved over time: for example, 'shaking' when a user interacts with them [7] or mimicking the movements a button makes when pressed [5]. Voxels can be augmented by projecting onto them [12,19] or surrounding surfaces [12].…”

“…Unlike typical screens where display elements are contiguous, levitating particles need to be spaced apart. This is often out of necessity; for example, acoustically levitated particles need to be at least 0.5λ apart, or further to allow space for animated movements [7]. As a result, users can see through the display volume and the content within.…”

“…In recent work [7], we developed a mid-air gesture technique for selecting particles, with particles 'shaking' when users pointed at them. For more complex interactions, the movement speed was altered to differentiate system states.…”

“…LeviPath [21] (Figure 3, Left) used 3D object movement, with an approach that can be used to move more than one object independently. Point-and-Shake [7] (Figure 3, Right) used such levitating particle movement to create interactive voxels. The most common acoustic levitation method utilises standing waves.…”