1. A method of determining a position estimate of a mobile device, comprising: generating a plurality of proposed positions with associated likelihoods by analyzing information from one or more motion sensors in the mobile device; processing information from one or more light sensors in the mobile device to produce a list of candidate positions; eliminating at least one of the plurality of proposed positions using the list of candidate positions; and determining a position estimate for the mobile device based on remaining proposed positions and associated likelihoods.