Many modern conveniences rely on our ability to accurately pinpoint location. GPS makes this job much easier, but the system isn't perfect. There are many places where GPS signal is restricted, from underground tunnels, to inside buildings, and even outdoors if near large structures.
Dead Reckoning is an Android app that offers a solution. Using built-in smartphone sensors to track location, the app removes the reliance on GPS and makes the tracking process self-sufficient and offline.