1. A location system, comprising: a processor configured to implement location modules for an agent, wherein the modules comprise: a belief determination module configured to determine a predicted location from a probabilistic belief associated with an extent to which the agent is associated with a location represented on a directed graph, based, at least in part, on a comparison of an input image with a plurality of images associated with the directed graph; and a comparison module configured to analyze a currently collected input image having a highest probability of matching a current location to generate a list of indices representing features in the currently collected input image, and compare each of the indices representing features in the currently collected input image with a dictionary of indices representing locations in a three dimensional (3D) point cloud to obtain a metric-accurate location for the agent.