1. An apparatus for identifying a height of a feature of a moving object from a series of video images, said apparatus comprising: an image recording device that stores a time series of video images; and an image analysis device that is configured to execute a program of machine-executable instructions to identify a height of a group of salient points of a moving object, wherein said program includes the steps of: identifying a group of salient point pixels in a time series of video images, wherein said group of salient point pixels corresponds to a group of salient points having a common estimated height range and located on a moving object; generating a plurality of time series of homographied images by performing homography transformations on said time series of video images at homography reference planes having different heights above a surface on which said moving object travels; measuring inter-salient-point pixel distances between at least one pair of salient point pixels in said group of salient point pixels for a plurality of homographied images within each of said plurality of time series of homographied images; and determining a height of said group of salient points from a surface on which said moving object travels based on a measurement data on said inter-salient-point pixel distances.