A method for building a 3D model of an area of interest on the surface of a planet, the method comprising: - providing a plurality of 2D images from satellites, where each 2D image out of the plurality of 2D images at least partly covers the area of interest, and where each subarea of the area of interest is covered by a minimum of three images, taken from different angles, out of the plurality of 2D images; - performing bundle adjustments for the plurality of 2D images; - dividing the area of interest into parts, characterised in that, for each part of the area of interest: - taking all possible combinations of two images out of the minimum of three images covering that part of the area of interest, taken from different angles, out of the plurality of 2D images; and - establishing point matching correspondence for each such combination of two images so that a set of points for each such combination is achieved; - combining the sets of points for which point matching correspondence was established so that a final set of points is achieved; - building (240; 340) a 3D model of said part of the area of interest based on the final set of points; and - combining the 3D models from each part of the area of interest to a 3D model of the whole area of interest, where the images in the plurality of 2D images are taken from at least two different satellites. - providing a plurality of 2D images from satellites, where each 2D image out of the plurality of 2D images at least partly covers the area of interest, and where each subarea of the area of interest is covered by a minimum of three images, taken from different angles, out of the plurality of 2D images; - performing bundle adjustments for the plurality of 2D images; - dividing the area of interest into parts, characterised in that, for each part of the area of interest: - taking all possible combinations of two images out of the minimum of three images covering that part of the area of interest, taken from different angles, out of the plurality of 2D images; and - establishing point matching correspondence for each such combination of two images so that a set of points for each such combination is achieved; - combining the sets of points for which point matching correspondence was established so that a final set of points is achieved; - building (240; 340) a 3D model of said part of the area of interest based on the final set of points; and - taking all possible combinations of two images out of the minimum of three images covering that part of the area of interest, taken from different angles, out of the plurality of 2D images; and - establishing point matching correspondence for each such combination of two images so that a set of points for each such combination is achieved; - combining the sets of points for which point matching correspondence was established so that a final set of points is achieved; - building (240; 340) a 3D model of said part of the area of interest based on the final set of points; and - combining the 3D models from each part of the area of interest to a 3D model of the whole area of interest, where the images in the plurality of 2D images are taken from at least two different satellites.