1. A method for determining a user's location in a pre-mapped environment from one or more images of the user's vicinity, the method comprising: providing a first data structure, wherein the first data structure is a probabilistic data structure derived from a second data structure; querying the second data structure for corresponding feature characteristics stored in the second data structure that respectively correspond to each feature characteristic from a plurality of feature characteristics, wherein the plurality of feature characteristics is a subset of an initial plurality of feature characteristics extracted from the one or more images of the user's vicinity, and wherein the plurality of feature characteristics is determined by queries to the first data structure; and identifying the user's location in the pre-mapped environment from the corresponding feature characteristics.