Abstract
The past decade's research in visible light positioning (VLP) has led to technologies with high location precision. However, existing VLP systems either require specialized LEDs which hinder large-scale deployment, or need cameras which preclude continuous localization because of high power consumption and short coverage. In this paper, we propose Pulsar, which uses a compact photodiode sensor, readily fit into a mobile device, to discriminate existing ceiling lights---either fluorescent lights or conventional LEDs---based on their intrinsic optical emission features. To overcome the photodiode's lack of spatial resolution, we design a novel sparse photogrammetry mechanism, which resolves the light source's angle-of-arrival, and triangulates the device's 3D location and even orientation. To facilitate ubiquitous deployment, we further develop a light registration mechanism that automatically registers the ceiling lights' locations as landmarks on a building's floor map. Our experiments demonstrate that Pulsar can reliably achieve decimeter precision in both controlled environment and large-scale buildings.