T2IRay: Design of Thumb-to-Index based Indirect Pointing for Continuous and Robust AR/VR Input

Free-hand interactions have been widely deployed for AR/VR interfaces to promote a natural and seamless interaction experience. Among various types of hand interactions, microgestures are still limited in supporting discrete inputs and in lacking a continuous interaction theme. To this end, we propose a new pointing technique, T2IRay, which enables continuous indirect pointing through microgestures for continuous spatial input. We employ our own local coordinate system based on the thumb-to-index finger relationship to map the computed raycasting direction for indirect pointing in a virtual environment. Furthermore, we examine various mapping methodologies and collect thumb-click behaviors to formulate thumb-to-index microgesture design guidelines to foster continuous, reliable input. We evaluate the design parameters for mapping indirect pointing with acceptable speed, depth, and range. We collect and analyze the characteristics of click behaviors for future implementation. Our research demonstrates the potential and practicality of free-hand micro-finger input methods for advancing future interaction paradigms.