MagDesk: Interactive Tabletop Workspace Based on Passive Magnetic Tracking

Accurate and responsive 3D tracking enables interactive and context-aware 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. This paper introduces 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 signal processing 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 an average positional and orientational error of 2.49 mm and 0.72 ° near the table surface and 14.40 mm and 2.25° across the entire sensing range. To demonstrate MagDesk's object-tracking capabilities, this work presents a series of magnetic widgets for tangible interactions and explores two applications - a 3D drawing interface and augmented-reality tabletop games. By instrumenting a regular table surface, MagDesk presents a low-cost and accurate approach to 3D tracking passive objects for home and office environments.