1. A system for aiding an inertial navigation system of a vehicle, the system for aiding the inertial navigation system comprising: an imager configured to output signals associated with features passing through a field view of the imager over a plurality of image frames; and a processing unit operatively coupled the imager and configured to be operatively coupled to the inertial navigation system, the processing unit being configured to: determine a distance from the imager to one or more of the features passing through the field of view of the imager for a given image frame based on the signals, track at least one of the features from a first image frame containing the feature to any subsequent image frame while the feature remains within the field of view of the imager, calculate position information associated with the inertial navigation system relative to first tagged coordinates of each tracked feature, and update navigation information associated with the vehicle based on the calculated position information, wherein the signals associated with features passing through the field view of the imager comprise pixel signals associated with terrain features.