A method, apparatus, system, and computer program product for operating an aerial imaging system. A first altitude of a first aircraft is determined, by a computer system, using first images of a key point generated by the first aircraft during a flight and stereo depth triangulation. The first altitude is compared with a second altitude of a second aircraft determined by the second aircraft, by the computer system, to form a comparison. An offset between the first altitude and the second altitude is determined, by the computer system, using the comparison. At least one of the first altitude or the second altitude is adjusted based on the offset. A plurality of images of a region from the first aircraft at the first altitude and from the second aircraft at the second altitude is obtained.