The problem of the geo-referencing of unknown terrestrial objects with use of the space snapshots is an important part of remote sensing of the Earth. For resolving the above-mentioned problem, the onboard optical-electronic system of the low-Earth spacecraft is used as well as special imaging schemes and calculation algorithms should be elaborated. The main purpose of this paper is to propose and to study such new algorithms.

      We consider two fundamentally different algorithms for the geo-referencing of terrestrial objects using space snapshots. The first of these algorithms is based on the photogrammetric condition of collinearity. The second one is leant upon the rules of triangles resolution.

      The geo-referencing includes the flight stage as the shooting of objects from the orbit and the ground stage as the processing of images transmitted to the ground altogether with the synchronously received indications of the star tracker and the equipment of GPS customer. It is believed that the preliminarily supposed location of the geo-referencing object is known with accuracy of the order of 1 ... 2 km or hundreds of meters. This allows us to direct the camera's optical axis to the vicinity of the geo-referencing object in such a way that to be ensured that this object is captured by the field of view of the camera and the geo-referencing has accuracy of the order of tens of meters. Unlike other algorithms, our approach does not require the use of an ellipsoid that approximates the shape of the Earth, and, consequently, the proposed algorithms are free of the inconvenience associated with possible local inaccuracies of such approximation.

      The numerical simulation had demonstrated a satisfactory accuracy of the proposed geo-referencing algorithms in accordance with the aforesaid demands.

     We conclude that the proposed algorithms may be effectively applied for the geo-referencing of terrestrial objects with use of space snapshots.