1. A system for calibrating multi-camera array images, comprising: a. an array of at least four acquisition devices, configured to acquire images; b. at least one reference acquisition device configured to acquire at least one reference image at least partially overlapping at least four of said images; wherein the distance between at least one reference acquisition device and each of at least one of the acquisition devices of said array is smaller or equal to: Z * cos ⁢ ⁢ α h * cos ⁡ ( α + γ ) * ArrayCamGSD wherein Z is the minimal vertical distance between the at least one reference acquisition device and the highest ground point in the images and in the at least one reference image; h is the distance between the highest ground point in the images and the at least one reference image and the lowest ground point in the images and the at least one reference image; α is the elevation angle of said array to the highest ground point in the images and the at least one reference image; γ is the grazing angle of said array in respect of the average ground plain within said images and said reference images; and ArrayCamGSD is the minimal Ground Sampling Distance (GSD) of each of the array cameras, and wherein said at least one reference acquisition device is of superior geometric accuracy with respect to the at least four acquisition devices, and c. a processor configured to extract tie points between said at least four of said images and said at least one reference image and utilize said tie points for calibrating said at least four of said images in respect of said at least one reference image.