We propose Magemite, a fine-grained input system that exploits the around device space (ADS) as an expansion of the limited input area. The key insight underlying Magemite is, magnetic sensor integrated in smart devices can sense nearby magnetic field strength. Using a permanent magnet, users could “write” in ADS to communicate with matched devices. Different from previous magnetic-sensing schemes that recognize only coarse-grained gestures, Magemite can recognize user’s fine-grained input like characters.
However, individual’s diverse writing patterns affect the recognition accuracy. To address this challenge, we preprocess the input trajectories and abstract different features of trajectories to uniquely identify user’s input, then use these feature vectors to train several pattern recognition models for character recognition. We evaluate Magemite in various scenarios, and experimental results show Magemite can achieve average recognition accuracy over 85%.