Vulture

Abstract

Word-gesture keyboards enable fast text entry by letting users draw the shape of a word on the input surface. Such keyboards have been used extensively for touch devices, but not in mid-air, even though their fluent gestural input seems well suited for this modality. We present Vulture, a word-gesture keyboard for mid-air operation. Vulture adapts touch based word-gesture algorithms to work in midair, projects users' movement onto the display, and uses pinch as a word delimiter. A first 10-session study suggests text-entry rates of 20.6 Words Per Minute (WPM) and finds hand-movement speed to be the primary predictor of WPM. A second study shows that with training on a few phrases, participants do 28.1 WPM, 59% of the text-entry rate of direct touch input. Participants' recall of trained gestures in mid-air was low, suggesting that visual feedback is important but also limits performance. Based on data from the studies, we discuss improvements to Vulture and some alternative designs for mid-air text entry.

Investigating Tilt-based Gesture Keyboard Entry for Single-Handed Text Entry on Large Devices

“…It gained popularity on touch screen devices but not in other input modalities. Recently, Vulture [21] explores shape writing in mid-air, and achieves 11.8 wpm (first session) and 20.6 wpm (tenth session). However, it requires a complex setup involving optical markers and is not practical for mobile computing.…”

Agency in Mid-air Interfaces

“…Freeman and Lantz added light, audio and tactile displays to assist users to know "where to gesture" [16]. Markussen et al implemented a gestural typing system helped with visual feedback through a virtual keyboard [36]. Liu et al added visual hand-cursors on-screen to make users know the state of the bare-hand postures and gestures [33].…”

TiTAN

“…Each technique is further differentiated by the device it uses, be it controllerbased, marker-based or freehand input. Yet, existing approaches for midair text entry often suffer from inherent constraints, such as requiring a user to hold an external device (Wiimote) [6] or even wearing multiple reflective markers that are tracked by expensive infrastructure [12]. Whereas other device-free approaches [5,7] only allow single character entry at a time, and only utilize one hand, which can be ineffective or may cause strain on that hand.…”

“…Midair interaction [1,5,7,12,14,17,18,20,22] is an emerging input modality for HCI, in particular for scenarios involving public displays [11,18], large surface [15], augmented and virtual reality [1] and sterile conditions (e.g., surgery). However, midair text entry has not received as much attention with most solutions requiring either the use of an external controller [1,6,14] or reflective markers [12].…”

“…However, midair text entry has not received as much attention with most solutions requiring either the use of an external controller [1,6,14] or reflective markers [12]. Text entry, in midair, can be useful in many walk-up-and-use scenarios where an external device or touch screen is not available.…”