THREE YEARS OF MARS CARTOGRAPHY USING HRSC DATA
J. Albertz1, S. Gehrke1, H. Lehmann1, M. Waehlisch2, G. Neukum3
1 - Technische Universitaet Berlin, Geodesy and Geoinformation Science
2 - German Aerospace Center (DLR), Institute for Planetary Exploration
3 - Freie Universitaet Berlin, Institute of Geosciences
Since January 2004, the High Resolution Stereo Camera (HSRC) on board of Mars Express is imaging the Martian surface. The data acquired provide both full color and systematic stereo; it is well suited to derive color orthoimages, Digital Terrain Models, and, based on that, topographic and thematic maps. The standard map series of the Mars Express mission is the Topographic Image Map Mars 1:200,000. The planet Mars is covered by altogether 10.372 sheets in equal-area map projections, 10,324 of them in Sinusoidal Projection, supplemented by 48 polar sheets in Lambert Azimuthal Projection. The series’ layout scheme is flexible to the generation of special target maps, thematic maps, and related products.
In order to automate the generation of such maps, the cartographic software package Planetary Image Mapper (PIMap) has been developed at Technische Universität Berlin. The map production is predominantly carried out at the university in collaboration with the German Aerospace Center (DLR), which is responsible for photogrammetric processing of HRSC data. Other HRSC Team members are involved, especially with regard to thematic mapping.
An average sheet of the Topographic Image Map Mars 1:200,000 displays approximately 120x120 km; considering an HRSC image width of 60 km in highest resolution of 12 m/pixel, it is evident that mosaics of adjacent orbits are necessary to cover the mapped area. Therefore, especially in the early stage, map sheets needed to be adapted to individual orbits by location and/or scale. The first maps within the regular sheet lines could be generated in summer 2004. Until the present day, a variety of topographic and also thematic maps of different Martian regions has been produced – including, e.g., the first large-scale maps of the north-polar region, which combine HRSC imagery and Mars Orbiter Laser Altimeter (MOLA) contours. Furthermore, it has been shown that HRSC data of highest resolution are suitable for mapping in scales up to 1:100 000 and even 1:50 000, which can be systematically achieved by dividing standard sheets into quarters and sixteenth, respectively. A benefit of future map sheets will be the inclusion of the Catalog of Large Martian Impact Craters (companion abstract by Gehrke et al.).
In conclusion, the Topographic Image Map Mars 1:200,000 series has proven to be a useful and guide-lining standard. From the experience gained during three years of HRSC cartography and operational application of the software PIMap it is clear that we are well prepared for systematic map generation from HRSC data.