Multi-resolution topographic data extraction from Martian stereo imagery

Abstract

The acquisition of high resolution topographic data such as Digital Terrain Models (DTMs) and orthoimages from various Martian stereo imagery is now readily available. The very successful European Space Agency (ESA) Mars Express mission includes the High Resolution Stereo Camera (HRSC) which has provided, since March 2004, an increasingly global set of along-track stereo coverage at relatively high spatial resolution (<100 m, mainly 12.5–25 m) over the Martian surface. Previous DTM generation was only accomplished with planned or serendipitous Viking Orbiter and more recently from Mars Orbiter Camera Narrow Angle (MOC-NA) stereo-pairs. Neither system was designed for stereo photogrammetric DTM generation. Recently, the NASA Mars Reconnaissance Orbiter (MRO) deployed two major optical pushbroom CCD cameras which are capable of across-track stereo targeting. Both Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) provide very high resolution stereo imagery at 6 m and submetre, respectively. A stereo processing chain has been developed which uses a non-rigorous sensor model with geodetic control derived from a reference stereo data source (HRSC) and is here shown to be successfully applied to CTX and HiRISE stereo imagery for 3 test areas. This processing chain is here demonstrated to generate excellent quality DTMs (up to a maximum grid spacing of 0.7 m with HiRISE and 10 m with CTX) and associated ortho images. The photogrammetric quality of these products is here verified using inter-comparisons with HRSC and Mars Orbiter Laser Altimeter (MOLA) data sets and shows good agreement.