Coordinate registration by automated crater recognition

An algorithm for the automatic recognition of impact craters is presented, based on Hough transforms and accounting for both the circularity of the crater rim and the presence of the internal depression. The algorithm is applied to adjust a catalogue of crater coordinates originally measured in the context of the USGS 1:2M controlled photomosaic to the more precise geodetic grid derived from the Mars Orbiter Laser Altimeter experiment of the Mars Global Surveyor mission. The transformed coordinates are used to generate a global displacement field which may be used as a general transformation between the two coordinate systems. The feasibility of using the new coordinates to extract topographic profiles passing through the crater centres is demonstrated. The potential application of the algorithm for surface dating using the HRSC stereoscopic images and for searching for unknown impact structures on the Earth is discussed.