1. A method of capturing and processing images of an area of terrain, the method comprising: for each of a plurality of time-steps within a time period, using each of a plurality of modular cameras in a camera array, simultaneously generating an image Of a respective portion of terrain, wherein the modular cameras in the camera array have substantially fixed positions relative to each other, and the portions of terrain are such that a whole of an area of terrain has been imaged by an end of the time period; processing all images from the modular cameras to identify an object of interest in those images; from each image in which the object of interest has been identified, extracting a sub-image containing that object of interest that has not previously been stored; selecting a subset of all images, the subset images being the minimum number of images that provides that the whole area of the terrain is covered by the portions of the terrain in the subset images alone; whereby the whole area of the terrain is oversampled, having intermediate images generated between the subset images; and wherein all images equals the subset images plus the intermediate images.