High‐resolution digital elevation models derived from Viking Orbiter images: Method and comparison with Mars Orbiter Laser Altimeter Data

Abstract

The purpose of this paper is to present a method to derive local and high‐resolution digital elevation models (DEM) of Mars from Viking Orbiter images. We focus on two aspects that appear to be new in photogrammetry applied to Mars: the correlation method and the relative orientation method based on the analysis of the coplaneity. We demonstrate that a DEM from two Viking Orbiter images selected according to the criteria of parallax height ratio, resolution, and illumination conditions can be obtained with a better spatial lateral resolution than the interpolated Mars Orbiter Laser Altimeter (MOLA) data. Two images on the Deuteronilus Mensae area satisfy these criteria. The algorithm of reconstruction of the topography is divided into two steps. First, a correlation method at subpixel level based on Fourier transform has been adapted to extract image location of homologous points. As initial camera positions and angles are known with poor accuracy, an adjustment is then carried out by the method of relative orientation which requires no absolute control points and takes advantage of the subpixel accuracy of our matching algorithm. Finally, the DEM is projected into a Martian reference frame and registered to MOLA data for validation. The spatial resolution depends on the roughness of the area and is locally close to the distance between individual MOLA footprints along one profile (300 m), as demonstrated from the comparison with MOLA profiles. These first results of high‐resolution DEM from Viking Orbiter images should be used with MOLA data for many geological studies that require high‐resolution topographic data.