Keywords
Android, Walking, Map, Navigation, Sensors

Technologies
Kotlin, Android, Sensors, GPS, BLE

The application which I like to call Thereabouts is an Android app that uses Pedestrian Dead Reckoning (PDR) techniques to estimate a user’s position within a building.

Common use cases are where GPS is unavailable or inaccurate such as underground parking or metros. The app is designed with the intention of crowdsourcing map data, independent of building owners, to encourage a community of users. Users perform calibration of their stride to determine their stride length and step sensitivity.

When a user approaches a building, they are notified and can load that building’s map, currently including the Western Gateway Building. Their position is displayed on the map and they can move about. Movement is detected using steps, and direction is inferred by Compass and Gyroscope readings. An uncertainty model is implemented to show the user a confident radius around them to account for errors. Some accuracy improvement techniques are deployed, such as scrutinizing GPS readings and updates based on Bluetooth location advertisements from peers. Users are also provided detailed instructions and a range of settings.