1. A method for generating a disparity map, comprising the steps of: segmenting a first reference image acquired at a first time into one or more segments, each segment comprising a plurality of pixels, segmenting a corresponding second reference image acquired at the first time into one or more segments, each segment comprising a plurality of pixels; determining a disparity for one or more segments between the first reference image and the corresponding second reference image by overlaying the first reference image on the second reference image and performing subtraction between at least one of the one or more segments in the first reference image and corresponding segments in the second reference image; generating a first disparity map based upon the subtraction between the first image and the corresponding second image; segmenting a third reference image acquired at a second time image into one or more segments, each segment comprising a plurality of pixels, segmenting a corresponding fourth reference image acquired at the second time into one or more segments, each segment comprising a plurality of pixels; determining one or more altered segments comprising a difference between one of the first and second images acquired at the first time and one of the corresponding third and fourth images acquired at the second time; determining a disparity only for the determined one or more altered segments between the third reference image and the corresponding fourth reference image; generating a disparity map update including the one or more determined disparities for the one or more altered segments between the third reference image and the corresponding fourth reference image; generating a composite disparity map by combining the disparity map update and the first disparity map; and generating a depth map from the composite disparity map.