MagDesk: Interactive Tabletop Workspace based on Passive Magnetic Tracking

Accurate and responsive 3D tracking has the potential to enable interactive and contextaware workspaces, including mixed-reality 3D interfaces and collaborative tangible interactions. However, limitations of current tracking mechanisms – line-of-sight occlusion, drifting errors, small working volumes, or instrumentation that requires maintenance – ultimately restrict their adoption. We introduce MagDesk, an interactive tabletop workspace capable of real-time 3D tracking of passive magnets embedded in objects. Using a sensing array of 112 low-cost magnetometers underneath a table, our custom-designed signalprocessing and localization engine enables simultaneous tracking of multiple magnets in 5 degrees of freedom with millimeter accuracy. MagDesk can continuously and robustly track magnets at a maximum height of 600 mm over a 1750 mm (L) × 950 mm (W) table, while achieving average positional and orientational errors of 2.49 mm and 0.72 deg near the table surface and 14.40 mm and 2.25 deg across the entire sensing range. To demonstrate MagDesk's object-tracking capabilities, we present a series of magnetic widgets for tangible interactions and explore three applications – an interactive tangible dashboard, a 3D drawing interface, and augmented-reality tabletop games. By instrumenting a standard table surface, MagDesk presents a low-cost, accurate approach to 3D tracking of passive objects in home and office environments.