ACCURACY VALIDATION OF TILTED CAMERA SETUPS IN OPEN SKIES PROJECT AND MAPPING APPLICATIONS

Abstract. Signed March 24, 1992, the Open Skies Treaty permits each state-party to conduct short-notice, unarmed, reconnaissance flights over the others' entire territories to collect data on military forces and activities. Observation aircraft equipped with sensors shall enable the observing party to identify significant military equipment. The Open Skies Treaty agreed on an observation of 30cm GSD. Based on 8 mid-format cameras for 3 flight levels, a system was adjusted to comply with the regulations. However, the overall aim was to also use the system for mapping purposes in Romania, specifically the medium altitude configuration. From this medium altitude configuration, one specific combination raised our interest. The designed wide corridor mapping system, using two RGB tilted cameras and one RGB nadir camera generates a certain range of resolution of the sideward looking tilted cameras and a non-homogenous distribution of the GSD in the overlapping areas. While a reduction of the GSD in the remote parts of the tilted cameras is a well-known and accepted fact, the effect in the overlap of the tilted cameras with the nadir one is the opposite mathematically. In some cases, such an effect can cause a better GSD in these areas than expected.