The High Resolution Stereo Camera (HRSC) of Mars Express and its approach to science analysis and mapping for Mars and its satellites (original) (raw)
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Earth and Planetary Science Letters, 2010
Mars global planetary mapping stereo imaging digital terrain model orthoimage We report on the results of the Mars Express High-Resolution Stereo Camera (HRSC) experiment pertaining to one of its major aims, mapping the surface of Mars by high-resolution digital terrain models (DTM, up to 50 m grid spacing) and orthoimages (up to 12.5 m resolution). We introduce the specifications and characteristics of these data products and give an overview of the procedures that have been developed and are applied for their derivation. We also address the performance characteristics of the mapping project related to different aspects of internal accuracy, accuracy with respect to the global reference system, and regional aspects. Using adaptive processing techniques for terrain reconstruction and a revised approach to the improvement of orientation data, a mean precision of the resulting 3D points of about 12 m is obtained, exceeding the mean ground resolution of the stereo images. Using Mars Orbiter Laser Altimeter (MOLA) data, the HRSC models are firmly tied to the global reference system at the scale of the HRSC DTM grid spacing in the lateral dimension, and to within few meters vertically. HRSC high-resolution DTMs are typically generated using a grid size of about 2 times the mean ground resolution, but usually not larger than 3 times the mean ground resolution, and not smaller than 3 times the precision of the integrated 3D points derived from stereo image analysis. Statistically, every grid cell is based on at least one measured 3D point. Thus, horizontal DTM resolution is well established with regard to the precision and density of the derived 3D points, while the concurrent aim of a detailed terrain representation at maximum possible resolution is pursued. Comparison with the DTM derived from MOLA data allows us to identify specific advancements related to this updated view of Martian topography. We also address the mapping performance of HRSC in comparison to MOLA with respect to latitude and to different surface types and morphologies. Finally, comparison with MOLA highlights typical complementarities of the two different approaches for mapping planetary surfaces.
Planetary and Space Science, 2007
ESA's Mars Express has successfully completed its nominal mission of one Martian year covering about 25% of the surface in stereo and color with resolutions up to 10 m/pixel by its high-resolution stereo camera (HRSC). Mars Express is now in its extended mission phase, during which much of the remaining part of the Martian surface is envisaged to be covered in stereo and color. The HRSC instrument is designed to map the morphology, topography, structure and geologic context of the surface as well as atmospheric phenomena. This paper discusses the measurement principles and operations of the instrument as well as the acquisition, calibration and processing of regional and global data sets. As HRSC is a push-broom scanning instrument with nine CCD line detectors mounted in parallel on a focal plane, its unique feature is the ability to obtain near-simultaneous imaging data at high resolution, with along-track triple stereo, four colors and five different phase angles, avoiding any time-dependent variations of the observing conditions. The HRSC spatial resolution is 10 m/pixel at the nominal periapsis altitude of 250 km, with an image swath of 53 km, and 2.3 m/pixel for an additional framing CCD device, called super resolution channel (SRC), practically working as an additional tenth channel of the HRSC and yielding nested-in black and white images for studies of small-scale geologic features. The sub-pixel accuracy of the threedimensional point determination allows the derivation of digital terrain models (DTMs) with a grid size of up to 50 m and a height accuracy of a single pixel with up to 10 m, thus enabling us to carry out detailed quantitative analyses of the surface structure. The HRSC (1) bridges the gap between the medium-high-resolution Viking imagery and the very-high-resolution Global Surveyor mission, thus providing geological context, and (2) fills the gaps in the three-dimensional coverage and DTM grid of the MOLA laser altimetry data, and (3) helps characterize landing sites for in-situ measurements. HRSC also builds the basis for extended compositional mapping when combining spectral information with topographic photomaps over large areas. So far the HRSC measurements have made a significant contribution to the study of the evolution of volcanism and the role of water and ice throughout the Martian history.
The High Resolution Stereo Camera (HRSC) onboard the European Space Agency’s (ESA) Mars Express (MEX) has been orbiting Mars since December 2003. One of the main aims is to cover Mars globally in color and stereoscopically at high resolution. HRSC has so far covered almost half of the surface of Mars at a resolution better than 20 meters per pixel. High resolution digital terrain models (DTM) are necessary for geoscientific studies of Mars. To get a more comprehensive view of regional processes on Mars, images as well as topographic data have to be mosaicked photogrammetrically. This paper briefly describes the simultaneous adjustment of exterior orientation for six HRSC orbit strips covering the Mawrth Vallis region, based on tie point matching and bundle block adjustment as well as the derivation of a DTM mosaic with a ground resolution of 75 m per pixel and an ortho-image mosaic with a ground resolution of 12.5 m per pixel.
HRSC on Mars Express – Photogrammetric and Cartographic Research
Photogrammetric Engineering & Remote Sensing, 2005
The High Resolution Stereo Camera (HRSC) on the European spacecraft Mars Express is the first camera on a planetary mission especially designed for photogrammetric and cartographic purposes. Since January 2004 the camera has been taking image data from the Martian surface, characterized by high-resolution, stereo capability and color. These data provide an enormous potential for the generation of 3D surface models, color orthoimages, topographic and thematic maps, and additional products. The image data acquired undergo calibration and systematic processing to orthoimages and 3D data products. Within the international HRSC Science Team
MARS: HIGH-RESOLUTION DIGITAL TERRAIN MODEL AND ORTHOIMAGE MOSAIC ON THE BASIS OF MEX/HRSC DATA
The High Resolution Stereo Camera (HRSC) onboard the European Space Agency's (ESA) Mars Express (MEX) has been orbiting Mars since December 2003. One of the main aims is to cover Mars globally in color and stereoscopically at high resolution. HRSC has so far covered almost half of the surface of Mars at a resolution better than 20 meters per pixel. High resolution digital terrain models (DTM) are necessary for geoscientific studies of Mars. To get a more comprehensive view of regional processes on Mars, images as well as topographic data have to be mosaicked photogrammetrically. This paper briefly describes the simultaneous adjustment of exterior orientation for six HRSC orbit strips covering the Mawrth Vallis region, based on tie point matching and bundle block adjustment as well as the derivation of a DTM mosaic with a ground resolution of 75 m per pixel and an ortho-image mosaic with a ground resolution of 12.5 m per pixel.
The mapping performance of the HRSC/SRC in Mars orbit
RED
The images obtained by the HRSC (High Resolution Stereo Camera) on Mars Express show excellent potential for topographic mapping of the planet. The derived stereo models agree with topographic data obtained earlier by MOLA (Mars Orbiter Laser Altimeter) on the Mars Global Surveyor: For the image scenes from the Mars-Express commissioning phase that were studied, we find absolute differences in heights as small as 50 m and lateral positional differences along MOLA tracks of about 100 m. We show that HRSC effectively fills the gaps left between the MOLA tracks. SRC (Super Resolution Channel) images are well placed at their nominal geometric positions and reveal further detail within the HRSC context images. However, many of the images, fall short of the expected image quality for reasons to be examined.
Remote Sensing and Data Analyses on Planetary Topography
Remote Sensing
Planetary mapping product established by topographic remote sensing is one of the most significant achievements of contemporary technology. Modern planetary remote sensing technology now measures the topography of familiar solid planets/satellites such as Mars and the Moon with sub-meter precision, and its applications extend to the Kuiper Belt of the Solar System. However, due to a lack of fundamental knowledge of planetary remote sensing technology, the general public and even the scientific community often misunderstand these astounding accomplishments. Because of this technical gap, the information that reaches the public is sometimes misleading and makes it difficult for the scientific community to effectively respond to and address this misinformation. Furthermore, the potential for incorrect interpretation of the scientific analysis might increase as planetary research itself increasingly relies on publicly accessible tools and data without a sufficient understanding of the u...
An Ortho-Image Map using Data Obtained from the Mars Orbiter Camera of Mars Global Surveyor
INTERNATIONAL …, 2002
A basic requirement for the planning of future Mars missions are precise and high resolution maps, especially, of the landing site area. We present a new digital orthoimage map of Mars using data obtained from the Mars Orbiter Camera (MOC) of the Mars Global Surveyor (MGS). The new map covers the Mars surface from 180° E (180° W) to 360° E (0° W) and from 60° South to 60° North with a resolution of 231.529 m/pixel (256 pixel/degree). The mosaic was divided into 8 parts, according to the digital size of the Mars Digital Image Mosaics (MDIM2). They are available digitally at http://solarsystem.dlr.de/PG/MOC/. In addition, we announce the release of a printed map of Coprates (MC 18) based on MGS data. For map creation, digital image processing methods have been applied. Furthermore, we developed a general processing method for creating image mosaics based on MOC data. This method can be used for creating image mosaics using CCD (Charged Coupled Device) line camera data and it is applicable also for other Mars missions, whenever a CCD line camera is employed.