Touchless circular menus: toward an intuitive UI for touchless interactions with large displays

Researchers are exploring touchless interactions in diverse usage contexts. These include interacting with public displays, where mouse and keyboards are inconvenient, activating kitchen devices without touching them with dirty hands, or supporting surgeons in browsing medical images in a sterile operating room. Unlike traditional visual interfaces, however, touchless systems still lack a standardized user interface language for basic command selection (e.g., menus). Prior research proposed touchless menus that require users to comply strictly with system-defined postures (e.g., grab, finger-count, pinch). These approaches are problematic because they are analogous to command-line interfaces: users need to remember an interaction vocabulary and input a pre-defined symbol (via gesture or command). To overcome this problem, we introduce and evaluate Touchless Circular Menus (TCM)---a touchless menu system optimized for large displays, which enables users to make simple directional movements for selecting commands. TCM utilize our abilities to make mid-air directional strokes, relieve users from learning posture-based commands, and shift the interaction complexity from users' input to the visual interface. In a controlled study (N=15), when compared with contextual linear menus using grab gestures, participants using TCM were more than two times faster in selecting commands and perceived lower workload. However, users made more command-selection errors with TCM than with linear menus. The menu's triggering location on the visual interface significantly affected the effectiveness and efficiency of TCM. Our contribution informs the design of intuitive UIs for touchless interactions with large displays.