1. A method for generating a disparity map, comprising the steps of: generating a first disparity map for images acquired at a first time; determining one or more objects or portions of objects that change position between the images acquired at the first time and images acquired at a second time; generating disparity map update segments corresponding to the objects or portions of objects, wherein a determination of disparity between the images acquired at the second time is performed only on portions thereof that have changed from one or more of the images acquired at the first time; and combining the first disparity map and the disparity map update segments.