1. A method to uniquely identify a mobile object depicted in an image, wherein the image is captured from an elevated or aerial platform, said method comprising the steps of: analyzing the image to detect machine-readable code associated with the depicted mobile object, wherein the mobile object is steganographically marked with the machine-readable code prior to image capture, and wherein the machine-readable code comprises an identifier; decoding the machine-readable code to obtain the identifier; and identifying the mobile object via the identifier.