Quantitative Assessment of Automated Crater Detection on Mars

Crater Size-Frequency Distributions (SFD) on planetary surfaces are crucial to dating the geological age. On the Moon they have been employed together with radioactive K-Ar techniques to determine ages of different regions. The launch of the ESA Mars Express (MEX) mission on 6 June 2003 with the 9-view camera HRSC (High Resolution Stereo Camera) orbiting instrument and subsequent spectacular multi-angle and colour data acquired since January 2004 opens up the possibility of applying the lessons learnt on the Moon to Mars. Although there is an on-line web-based cataloguing and mapping system at USGS which shows the location and characteristics of some 40,000 craters on Mars (Mars Crater Consortium, MCC) with diameters >5km, these craters represent only a tiny fraction of the millions of craters which are believed to be present on the Martian surface. It is highly unlikely that there will ever be sufficient resources to map these smaller craters using existing manually-intensive techniques. An automated crater detection algorithm has been developed which exploits both image data and DTMs derived from laser altimetry (MGS-MOC) and in future DTMs from HRSC. The algorithm is described and examples of it’s application for a variety of different crater types are demonstrated. Central to the application of any automated algorithm and prior to systematic application to the Martian planetary surface it is crucial to perform a quantitative assessment of any automated algorithm’s performance. We show results from three different approaches here: (1) inter-comparison of automated crater locations with those in the MCC catalogue; ; (2) intercomparison of automated crater locations with manually-derived crater locations; (3) simulation of crater images using an idealised 3D model of a Martian crater changing the illumination conditions.