Using the High Resolution Stereo Camera (HRSC), digital terrain models can be derived that illustrate the topography of the region using false colours. The altitudes can be read from the coloured scale at the top left of the image; north is to the right. In the absence of 'sea level', the elevation data are referenced to an areoid – a modelled equipotential surface on which everything experiences the same gravitational attraction towards the centre of the planet. The height differences between the bases of these two craters are easy to detect. The floor of Danielson Crater (blue, diameter approximately 60 kilometres) lies about 1000 metres lower than that of the smaller Kalocsa Crater (diameter approximately 33 kilometres).
As a joint undertaking by DLR, ESA and FU Berlin, the Mars Express HRSC images are published under a Creative Commons licence since December 2014: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO. This licence will also apply to all HRSC images released to date.