From 2D to 3D: Facilitating Single-Finger Mid-Air Typing on Virtual Keyboards with Probabilistic Touch Modeling

Mid-air text entry on virtual keyboards suffers from the lack of tactile feedback, bringing challenges to both tap detection and input prediction. In this poster, we demonstrated the feasibility of efficient single-finger typing in mid-air through probabilistic touch modeling. We first collected users' typing data on different sizes of virtual keyboards. Based on analyzing the data, we derived an input prediction algorithm that incorporated probabilistic touch detection and elastic probabilistic decoding. In the evaluation study where the participants performed real text entry tasks with this technique, they reached a pick-up single-finger typing speed of 24.0 WPM with 2.8% word-level error rate.