This paper explores how inertial Pedestrian Dead-Reckoning (PDR) location systems can be improved with the use of a light sensor to measure the illumination gradients created when a person walks under ceiling-mounted unmodified indoor lights. The process of updating the inertial PDR estimates with the information provided by light detections is a new concept that we have named Light-m... https://www.ealisboa.com/quick-save-Pentair-Female-to-Female-Hose-Adapter-4-For-Sectional-Hose-K21241B-top-mega/