DLR's High Resolution Stereo Camera (HRSC) on board Mars Express uses its nine sensors to record the surface of Mars from different angles. Teams of scientists at the DLR Institute of Planetary Research and the Freie Universität Berlin calculate digital terrain models from four stereo or photometric channels directed 'obliquely' forwards and backwards onto the martian surface, and the nadir channel directed vertically onto Mars, which assign height information to each pixel. The colour scale at the top right of the image shows the altitude in relation to the 'areoid' – an imaginary surface on Mars with the same gravitational pull. The height differences between the plateaus, plateaus of the mesas and depressions in between are over 2000 metres.