1. A method for compressing an uncategorized elevation map by means of digital image processing, comprising: a. converting said uncategorized elevation map into corresponding one or more uncategorized grayscale terrain images; b. calculating local and global parameters of said one or more uncategorized grayscale terrain images, which local and global parameters are based on contents of said one or more uncategorized grayscale terrain images; c. categorizing said one or more uncategorized grayscale terrain images into a corresponding category according to the calculated local and global parameters, wherein said corresponding category is based on contents of said one or more uncategorized grayscale terrain images; d. selecting optimal compression parameters for compressing said one or more categorized grayscale terrain images, wherein said optimal compression parameters are selected based on the calculated local and global parameters and based on said category into which said one or more grayscale terrain image is categorized; and e. compressing said one or more categorized grayscale terrain images by applying to it digital image processing, using said selected optimal compression parameters, wherein said calculated local parameters comprise standard deviation of said grayscale terrain image and at least one of minimal height of the terrain and maximal height of the terrain, and wherein said calculated global parameters comprise at least one of: approximation of water flow of the terrain; approximation of watershed of the terrain; and division of the terrain into homologous portions.