1. A computer-implemented method for generating a mosaic pixilated digital image from a plurality of acquired pixilated images, each acquired image being of a portion of a surface of an astronomical body, each acquired image having been acquired by a digital camera while the camera translated above the surface of the astronomical body, the method comprising: using a mathematical model of a surface shape of the astronomical body and 3-D ray tracing, from a model of the digital camera to the model of the surface of the astronomical body, to determine a plurality of locations on the surface of the astronomical body corresponding to respective locations in the plurality of acquired images to determine an extent to which the surface of the astronomical body was imaged by the plurality of acquired images; determining boundaries of the mosaic image based at least in part on the determined extent to which the surface of the astronomical body was imaged; and for each pixel within the determined boundaries of the mosaic image: using the mathematical model of the shape of the astronomical body and reverse 3-D ray tracing, from the model of the surface of the astronomical body to a model of an image plane of the digital camera, in each of at least one candidate image of the plurality of acquired images, determining a candidate pixel in the candidate image that geographically corresponds to the pixel in the mosaic image, thereby determining at least one candidate pixel; and assigning a value to the pixel in the mosaic image, based on a value of the determined at least one candidate pixel.