1. A computer-implemented method of tracking a subject and updating a path taken by the subject, the method being implemented by a computer that includes a physical processor, the method comprising: determining a path taken by a subject by obtaining tracking data, from a dead reckoning sensor associated with the subject, the path taken including a series of dead reckoning path points from an initial point of the subject and a current location of the subject and a distance between each set of adjacent dead reckoning path points among the series of dead reckoning path points; generating convex constraint data, while the subject is traveling the path taken, by obtaining data from at least one of a magnetic field sensor and a ranging sensor, wherein the convex constraint data is associated with at least one error bound; and applying the tracking data and the convex constraint data in a convex optimization method to update at least a portion of the path taken by the subject and to identify the current location of the subject, wherein the convex optimization method includes defining a convex objective function for one or more parameters associated with one or more of the path taken and the current location and minimizing the convex objective function based on the convex constraint data to adjust the distance for at least one set of adjacent dead reckoning path points.