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In contaminated sites, remediation measures mostly depend on previous high-resolution site characterization (HRSC) results. In the case of industrial sites, where there is a high pollution risk for groundwater, many hydrogeological models are often achieved using stratigraphy results of geological drilling after the monitoring network design. This approach is only sometimes possible when contaminant back diffusion from small low-permeability lenses and layers occurs within a high-permeability aquifer. This framework needs a significant resolution that can be obtained by coupling preliminary stratigraphic data with specific in situ activities. Results from these additional investigations may help to locate low-permeability layers and, consequently, to identify the most vulnerable areas towards which groundwater management must be deepened. The use of gamma rays in combination with the analysis of the pluviometric and hydrometric data and together with the time series of the concentrations of a given analyte can provide indispensable support for site characterization, the development of numerical groundwater contamination models and remediation procedures when back diffusion occurs. In this study, within an industrial site in the province of Benevento (Italy), based on stratigraphy, a 3D hydrogeological model has been set up and coupled with results of natural gamma radioactivity logs to detect the release of Chromium VI from low-permeability lenses. [ABSTRACT FROM AUTHOR]

Jezero crater has been selected as the landing site for the Mars 2020 Perseverance rover, because it contains a paleolake with two fan-deltas, inlet and outlet valleys. Using the data from the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE), we conducted a quantitative geomorphological study of the inlet valleys of the Jezero paleolake. Results show that the strongest erosion is related to a network of deep valleys that cut into the highland bedrock well upstream of the Jezero crater and likely formed before the formation of the regional olivine-rich unit. In contrast, the lower sections of valleys display poor bedrock erosion and a lack of tributaries but are characterized by the presence of pristine landforms interpreted as fluvial bars from preserved channels, the discharge rates of which have been estimated at 103–104 m3s−1. The valleys' lower sections postdate the olivine-rich unit, are linked directly to the fan-deltas, and are thus formed in an energetic, late stage of activity. Although a Late Noachian age for the fan-deltas' formation is not excluded based on crosscutting relationships and crater counts, this indicates evidence of a Hesperian age with significant implications for exobiology. [ABSTRACT FROM AUTHOR]

The first high-resolution Digital Terrain Model (DTM) of the entire South Pole of Mars has been produced. A modified version (Kim and Muller, 2009) of a NASA-VICAR-based pipeline developed by DLR (German Aerospace Centre) and JPL (Jet Propulsion Laboratory) has been employed with image matching based on the Gotcha (Gruen-Otto-Chau) algorithm (Shin and Muller, 2012) with a specialised setup for the polar region. DTM products have been produced with more than twice the resolution (50 m/pixel) of the gridded Mars Orbiter Laser Altimeter (MOLA) 512 pixels/degree (112 m/pixel) over the South Polar Residual Cap (SPRC) and the Mars South Polar region (82° - 90° S) in MOLA and areoid reference. The accuracy of the HRSC orbital DTMs are compared against a MOLA reference with good results. HRSC orthorectified strip images from 12.5 to 50 m have also been produced from the base DTMs and these have been processed into a 12.5 m mosaic. HRSC strip products are currently being assessed as base images for automatic co-registration of thousands of high-resolution images, making them geometrically consistent with the surface conditions imaged by HRSC. In some cases, Context Camera (CTX) DTMs have been automatically produced and co-registered to the HRSC image strips and these, in turn, are being employed for automated co-registration of higher-resolution images. • Full high-resolution Digital Terrain Model of the South Pole of Mars including the South Polar Residual Cap has been made. • The Digital Terrain Model has been assessed for its vertical and horizontal accuracy. • Nadir Images have been orthorectified and have been tested to automatically co-register thousands of high-resolution images. • With height information obtained from HRSC DTMs and features from ORIs, South Polar Residual Cap could be assessed in 3 Dimension. [ABSTRACT FROM AUTHOR]

Highlights • Two new types, half and elongates spiders, are newly reported (half) and newly classified (elongated) for the first time in this work. • A new spider formation model, detailing the mechanism of growth of central pits and radiating troughs, was proposed. • Spatial locations of spiders are non-random, revealed by the spatial randomness analysis, and in consistent with our proposed spider formation model. • Inhibited zones exist around spiders within which another spider is less likely to occur. • The formation mechanisms of half and elongated spiders indicate that the topography and substrate characterization play an important role in spider formation. Abstract The south polar area of Mars exhibits an abundance of distinctive and exotic landforms, most of which occur within the region covered by the seasonal CO 2 cap. Araneiform terrain (also referred to as terrain covered by "spiders") is one of these unusual geomorphic features, resulting from CO 2 sublimation driven seasonal erosion. The High Resolution Imaging Science Experiment (HiRISE) on board NASA's Mars Reconnaissance Orbiter (MRO) spacecraft has repeatedly imaged Angustus Labyrinthus, informally known as the Inca City region (81°S, 296°E), over a period of four Martian years, showing a variety of classic polar features associated with sublimation and deposition including spiders. We mapped the spiders´ spatial distribution in the Inca City region and classified them in view of their morphological and topographic characteristics into four types, fat, thin, half, and elongated spiders. The latter two are reported for the first time in this work. We find that the formation mechanisms of half and elongated spiders were substantially influenced by ridge boundaries topography and pre-existing linear depressions, respectively. Based on our observations, we extend the conceptual model of spider erosion, explaining new elements of the spider formation process. We interpret the causes of deviating araneiform species from thin spiders (i.e., half, elongated and fat spiders) in the context of the extended model. We consider the migration of pressurized CO 2 through the porous substrate towards breaches in the ice cover, and the influence of the substrate's cohesive strength on the development of spider legs. Analysis of the spatial distribution of a fat spider population revealed that the initiation locations of spiders are not random but more evenly spaced, indicating the existence of an inhibited zone around a newly formed spider, consistent with our interpretations of the formation mechanism. Our case study in the Inca City region provides new understanding in the formation process of basal sublimation-driven features and thus offers new insight into polar surface processes. [ABSTRACT FROM AUTHOR]

Antoniadi basin displays dark-toned dendritic ridges previously interpreted as inverted fluvial channels. Detailed observations of these dark-toned ridges as well as the geological units in the central region of Antoniadi basin are provided emphasizing images from the Colour and Stereo Surface Imaging System (CaSSIS), the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE) instruments. Results show that the dark-toned ridges are part of the most recent geological unit as they overlie, and thus postdate all plains of the central Antoniadi basin, which is Early Amazonian based on its crater size-frequency distribution. Our observations of the dark-toned ridges are not consistent with inverted fluvial channels: they do not widen in the expected downstream direction, they display a rubbly texture and lack layering at high resolution, and have lobes with local levees in place of channel heads. In addition, the branched ridges are more mafic in composition and display a relatively higher thermal inertia than their surroundings. This suite of characteristics is better explained by volcanic flows developed as distributary channels rather than fluvial tributary channels. The occurrence of dikes in the east and west of the studied region supports that these flows were formed by lava, perhaps a'a like flows as suggested by the rubbly texture, but with an unusually high degree of digitation. Alternatively, such a geometry could be explained by the emplacement of the lava along pre-existing fluvial valleys, but neither the underlying topography, nor two nearby older craters, exhibit signs of fluvial erosion. • Dark ridges within Antoniadi crater, Mars are outstanding features from their dendritic geometry. • Dendritic ridges display morphological characteristics of distributary flows rather than tributary channels. • Their morphology, composition and context suggest volcanic flows rather than fluvial flows. [ABSTRACT FROM AUTHOR]

Web‐based planetary image dissemination platforms usually show outline coverage of available data and offer querying for metadata as well as preview and download. While the usual form of presenting multiorbit data sets is to merge the data into a larger mosaic, for change detection purposes it is essential to maintain the individual images as an important snapshot of the planetary surface taken at a specific time. We introduce the web‐based interactive Mars Analysis and Research System (iMARS web‐GIS), which is specialized on planetary surface change analysis with novel tools for simultaneous visualization of single images as time series in their original sequence. As the data foundation, we use the vast quantity of automatically coregistered orthoimages and digital terrain models (DTM) from three NASA missions' instruments processed and ingested in the context of the EU‐funded iMars project. The baseline for the coregistered images are the High‐Resolution Stereo Camera (HRSC) multiorbit quadrangle image mosaics, which are based on bundle block‐adjusted multiorbit DTM mosaics. Additionally, we make use of the existing along‐track bundle‐adjusted HRSC single images and DTMs available at the planetary data archives. We provide two science cases for exemplary workflows of the multitemporal single‐image analysis, demonstrating the dedicated tools for surface change interpretation—one near Mawrth Vallis and one near the south pole. A web mapping application including the presented functionality has been implemented and is available at http://imars.planet.fu-berlin.de with the iMars project website ( http://www.i-mars.eu/web-gis) serving as a mirror. [ABSTRACT FROM AUTHOR]

For a systematic mapping of the Martian surface, the Mars Express orbiter is equipped with a multi-line scanner: Since the beginning of 2004 the High Resolution Stereo Camera (HRSC) regularly acquires long image strips. By now more than 4,000 strips covering nearly the whole planet are available. Due to the nine channels, each with different viewing direction, and partly with different optical filters, each strip provides 3D and color information and allows the generation of digital terrain models (DTMs) and orthophotos. To map larger regions, neighboring HRSC strips can be combined to build DTM and orthophoto mosaics. The global mapping scheme Mars Chart 30 is used to define the extent of these mosaics. In order to avoid unreasonably large data volumes, each MC-30 tile is divided into two parts, combining about 90 strips each. To ensure a seamless fit of these strips, several radiometric and geometric corrections are applied in the photogrammetric process. A simultaneous bundle adjustment of all strips as a block is carried out to estimate their precise exterior orientation. Because size, position, resolution and image quality of the strips in these blocks are heterogeneous, also the quality and distribution of the tie points vary. In absence of ground control points, heights of a global terrain model are used as reference information, and for this task a regular distribution of these tie points is preferable. Besides, their total number should be limited because of computational reasons. In this paper, we present an algorithm, which optimizes the distribution of tie points under these constraints. A large number of tie points used as input is reduced without affecting the geometric stability of the block by preserving connections between strips. This stability is achieved by using a regular grid in object space and discarding, for each grid cell, points which are redundant for the block adjustment. The set of tie points, filtered by the algorithm, shows a more homogenous distribution and is considerably smaller. Used for the block adjustment, it yields results of equal quality, with significantly shorter computation time. In this work, we present experiments with MC-30 half-tile blocks, which confirm our idea for reaching a stable and faster bundle adjustment. The described method is used for the systematic processing of HRSC data. [ABSTRACT FROM AUTHOR]

Understanding planetary atmosphere-surface exchange and extra-terrestrial-surface formation processes within our Solar System is one of the fundamental goals of planetary science research. There has been a revolution in planetary surface observations over the last 15 years, especially in 3D imaging of surface shape. This has led to the ability to overlay image data and derived information from different epochs, back in time to the mid 1970s, to examine changes through time, such as the recent discovery of mass movement, tracking inter-year seasonal changes and looking for occurrences of fresh craters. Within the EU FP-7 iMars project, we have developed a fully automated multi-resolution DTM processing chain, called the Coregistration ASP-Gotcha Optimised (CASP-GO), based on the open source NASA Ames Stereo Pipeline (ASP) [Tao et al., this conference], which is being applied to the production of planetwide DTMs and ORIs (OrthoRectified Images) from CTX and HiRISE. Alongside the production of individual strip CTX & HiRISE DTMs & ORIs, DLR [Gwinner et al., 2015] have processed HRSC mosaics of ORIs and DTMs for complete areas in a consistent manner using photogrammetric bundle block adjustment techniques. A novel automated co-registration and orthorectification chain has been developed by [Sidiropoulos & Muller, this conference]. Using the HRSC map products (both mosaics and orbital strips) as a map-base it is being applied to many of the 400,000 level-1 EDR images taken by the 4 NASA orbital cameras. In particular, the NASA Viking Orbiter camera (VO), Mars Orbiter Camera (MOC), Context Camera (CTX) as well as the High Resolution Imaging Science Experiment (HiRISE) back to 1976. A webGIS has been developed [van Gasselt et al., this conference] for displaying this time sequence of imagery and will be demonstrated showing an example from one of the HRSC quadrangle map-sheets. Automated quality control [Sidiropoulos & Muller, 2015] techniques are applied to screen for suitable images and these are extended to detect temporal changes in features on the surface such as mass movements, streaks, spiders, impact craters, CO2 geysers and Swiss Cheese terrain. For result verification these data mining techniques are then being employed within a citizen science project within the Zooniverse family. Examples of data mining and its verification will be presented. [ABSTRACT FROM AUTHOR]

The photogrammetric bundle adjustment of line scanner image data requires a precise description of the time-dependent image orientation. For this task exterior orientation parameters of discrete points are used to model position and viewing direction of a camera trajectory via polynomials. This paper investigates the influence of the distance between these orientation points on the quality of trajectory modeling. A new method adapts the distance along the trajectory to the available image information. Compared to a constant distance as used previously, a better reconstruction of the exterior orientation is possible, especially when image quality changes within a strip. In our research we use image strips of the High Resolution Stereo Camera (HRSC), taken to map the Martian surface. Several experiments on the global image data set have been carried out to investigate how the bundle adjustment improves the image orientation, if the new method is employed. For evaluation the forward intersection errors of 3D points derived from HRSC images, as well as their remaining height differences to the MOLA DTM are used. In 13.5 % (515 of 3,828) of the image strips, taken during this ongoing mission over the last 12 years, high frequency image distortions were found. Bundle adjustment with a constant orientation point distance was able to reconstruct the orbit in 239 (46.4 %) cases. A variable orientation point distance increased this number to 507 (98.6 %). [ABSTRACT FROM AUTHOR]

The surface of Mars has been an object of interest for planetary research since the launch of Mariner 4 in 1964. Since then different cameras such as the Viking Visual Imaging Subsystem (VIS), Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), and Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) have been imaging its surface at ever higher resolution. The High Resolution Stereo Camera (HRSC) on board of the European Space Agency (ESA) Mars Express, has been imaging the Martian surface, since 25th December 2003 until the present-day. HRSC has covered 100% of the surface of Mars, about 70% of the surface with panchromatic images at 10-20 m/pixel, and about 98% at better than 100 m/pixel (Neukum et. al., 2004), including the polar regions of Mars. The Mars polar regions have been studied intensively recently by analysing images taken by the Mars Express and MRO missions (Plaut et al., 2007). The South Polar Residual Cap (SPRC) does not change very much in volume overall but there are numerous examples of dynamic phenomena associated with seasonal changes in the atmosphere. In particular, we can examine the time variation of layers of solid carbon dioxide and water ice with dust deposition (Bibring, 2004), spider-like channels (Piqueux et al., 2003) and so-called Swiss Cheese Terrain (Titus et al., 2004). Because of seasonal changes each Martian year, due to the sublimation and deposition of water and CO2 ice on the Martian south polar region, clearly identifiable surface changes occur in otherwise permanently icy region. In this research, good quality HRSC images of the Mars South Polar region are processed based on previous identification as the optimal coverage of clear surfaces (Campbell et al., 2015). HRSC images of the Martian South Pole are categorized in terms of quality, time, and location to find overlapping areas, processed into high quality Digital Terrain Models (DTMs) and Orthorectified Images (ORIs) and projected into polar stereographic projection using DLR (Deutsches Zentrum für Luft- und Raumfahrt; German Aerospace Center)'s VICAR and GIS software with modifications developed by Kim & Muller (2009). Surface changes are identified in the Mars SPRC region and analysed based on their appearance in the HRSC images. [ABSTRACT FROM AUTHOR]

Images of Mars taken by spacecraft in the last few decades indicate that the landscape has changed and that current processes are continuously changing the surface. The modifications of the landscape are caused by exogenic processes including eolian activity, mass movement, the growth and retreat of the polar caps, glacial processes and crater-forming impacts. In particular the High Resolution Stereo Camera (HRSC) on board Mars Express (MEx) and the Context Camera (CTX) on board the Mars Reconnaissance Orbiter (MRO) cover large areas at high resolution and thus are particularly well-suited to detect the extent and origin of surface changes on Mars. Multi-temporal observations of variable features on Mars became possible by the increasing number of repeated image acquisitions of the same surface areas. To support the investigation of surface changes that represents a key element in martian research, we developed MUTED, the “Multi-Temporal Database of Planetary Image Data”, which is a tool for the identification of the spatial and multi-temporal coverage of planetary image data from Mars. Using MUTED, scientists are able to identify the location, number, and time range of acquisitions of overlapping images from, for example, HRSC and CTX. MUTED also includes images from other planetary datasets such as those of the Mars Orbiter Camera (MOC), the Thermal Emission Imaging System (THEMIS), and the High Resolution Imaging Science Experiment (HiRISE). The database supports the identification and analysis of surface changes and short-lived surface processes on Mars based on fast automatic planetary image database queries. From the multi-temporal planetary image database and investigations based on multi-temporal observations we will better understand the interactions between the surface of Mars and external forces, including the atmosphere. MUTED is available for the planetary scientific community via the webpage of the Institut für Planetologie (IfP) Muenster. [ABSTRACT FROM AUTHOR]

After more than ten years in orbit at Mars, the coverage from the High Resolution Stereo Camera (HRSC) on the European Space Agency’s Mars Express is sufficient to begin constructing mosaic products on a global scale. We describe our systematic processing procedure and, in particular, the technique used to bring images affected by atmospheric dust into visual consistency with the mosaic. We outline how the same method is used to produce a relative colour mosaic which shows local colour differences. We demonstrate the results and show that the techniques may also be applied to images from other orbital cameras. [ABSTRACT FROM AUTHOR]

The ' Shadow Method ' is a tool to estimate the Atmospheric Optical Depth (AOD) on Mars from the brightness of shadows. This method is derived from the equations of radiative transfer, but there are several important simplifications that together invoke errors of several tens of percent. Work by us and by others show that these errors are largely systematic and can be minimized by adding an empirical 'Correction-Factor' to the equations. To quantify this factor, we compared shadow method retrievals from orbiter images with in-situ measurements by the Curiosity rover. We analysed a set of seven images that was taken by DLR's High Resolution Stereo Camera (HRSC) on-board ESA's orbiter Mars Express. The images were taken in seven channels: NIR, red, green, blue, and in three panchromatic stereo channels S1, Nadir, and S2. All these images show Gale crater and the exploration site of the Curiosity rover therein. Comparing the rover measurement of the AOD with shadow method retrievals from 5 close-by regions yielded the following correction factors: 0.53 ± 0.03 for Nadir, 0.60 ± 0.04 for S1, 0.62 ± 0.03 for S2, 0.66 ± 0.03 for NIR, 0.64 ± 0.03 for Red, 0.55 ± 0.03 for Green, and 0.57 ± 0.03 for Blue. We analysed 71 regions with varying altitudes between −4.6 km to +3.8 km and found that, on an average, the AOD decreases with increasing altitude. The available channels yielded the following averages of atmospheric optical depth before applying the correction factor: Nadir: 0.47; S1: 0.46; S2: 0.52; Red: 0.49; Green: 0.53; Blue: 0.57 and NIR: 0.44 while after applying the correction factor we obtain Nadir: 0.89; S1: 0.77; S2: 0.84; Red: 0.77; Green: 0.96; Blue: 1.0 and NIR: 0.67. The Curiosity rover, at an altitude of −4.87 km, measured a ground-truth AOD of 0.88. The shadowed and sunlit comparison regions that were used for this work range in altitudes from −4.6 km to +3.8 km. The AOD decreases with altitude and the decrease yields the following scale heights: S1: 12.5 + 0.48/−0.35 km; nadir: 11.1 + 0.53/−0.33 km; S2: 14.3 + 0.48/−0.44 km; NIR: 11.1 + 0.56/−0.47 km; red: 14.3 + 0.52/−0.49 km; green: 15.6 + 0.62/−0.59 km; blue: 14.3 + 0.44/−0.42 km. For this area and around that time of day, the Mars Climate Database predicts a pressure scale height of 11.6–12.2 km, which agrees well with the scale heights that we derived for Nadir, S1 and NIR. One region (number 42) contained a cloud with an optical depth of up to 0.6—0.8; i.e., around one third of the total AOD of 1.9 ± 0.01 measured for this area. Region 29 showed the highest AOD of our sample. • The Atmospheric Optical Depth (AOD) can be estimated with the Shadow Method. • Images taken by Mars Express HRSC's, Red and NIR channels and by the panchromatic stereo channels S1, Nadir, and S2 yield better results than those taken by the blue and green channels. • We show that the AOD decreases with altitude. • We studied the optical depth of a cloud. [ABSTRACT FROM AUTHOR]

The High Resolution Stereo Camera (HRSC) on the European spacecraft Mars Express has high spatial resolution and global coverage. Thus, global high resolution topographic data from the Martian surface can be derived through photogrammetric processing of HRSC data., butthe accuracy and efficiency of image matching can be improved with geometric constraints of the epipolar line. A approximate epipolar re-sampling method which is fit for HRSC linear pushbroom imagery is proposed. Firstly, the epipolar geometry of HRSC image is analyzed using a projection trajectory method. Then, the original HRSC images were differentially rectified into a normalized image. Next, the epipolar geometry in the normalized image is analyzed and the approximate epipolar line direction determined. Lastly, the epipolar image is generated through epipolar resampling in normalized image. Experimental results demonstrate the feasibility of the proposed methodThe parallax in the y direction is less than one pixel in the epipolar resampled image. Moreover, the geometric distortion is decreased when image matching is performed on normalized images. [ABSTRACT FROM AUTHOR]

This paper presents a wide range of research and processing results in the area of multi-resolution orbital data co-registration, multiresolution ground 3D reconstruction, and orbit-to-ground data fusion, achieved within the EU-FP7 PRoVisG and PRoViDE project. We focus on three NASA rover missions, MER-A, MER-B, and MSL, to provide examples of automated methods for producing coregistered, multi-resolution 3D products. We highlight the mis-registration discovered between current HiRISE to HRSC datasets, CTX to HRSC and HiRISE to CTX co- results, wide baseline stereo reconstruction results of rover imagery, ground-to-orbit coregistration, i.e. reconstructed wide baseline ground ORI and HiRISE ORI co-registration, and extensive exploitation of the coregistered datasets in visualisation and interactive web-GIS. [ABSTRACT FROM AUTHOR]

Abstract: The use of numerical datasets of the same type derived from remote sensing instruments is often treated as equivalent in value and utility, within the limits of their spatial resolution. Surface topography is a good example of this. We used gridded digital terrain models (DTMs) derived from both laser altimetry and stereo pairs as well as the original laser data points to quantify the topography of impact craters, which have well-studied morphometry. The primary purpose was to test the accuracy of laser data given an image-based DTM with approximately a factor of 10 better spatial resolution; we used the Mars Orbiter Laser Altimeter and High-Resolution Stereo Camera datasets for this work. We found that the ability to derive accurate topographic information in laser altimetry diminished well before the ability to visually resolve the feature in the dataset, but we also found that laser point and gridded data-based results were in good agreement down to their resolution limits. Relative to the image-based DTM, pixel-for-pixel, the laser data were more useful in their ability to visibly resolve the impact craters. This work has implications for remote sensing in general, but specifically the application to limited sources of data for planetary surface topography, such as Mercury where the northern hemisphere topography is being measured with a laser altimeter but the southern hemisphere topography is based only on stereo pairs. [Copyright &y& Elsevier]

Abstract: We have developed a new optimisation based shape from shading algorithm which is able to make use of sophisticated camera and reflectance models and does not require a good initialising surface. Surface shape consistent with ground truth is obtained when the technique is applied to both synthetic rendered surfaces and real images captured by the Mars Express orbiter and HRSC instrument. The obtained surfaces provide improved fine surface detail over that found using stereo techniques and demonstrate the applicability of the technique to real images. [Copyright &y& Elsevier]

Abstract: Martian topographic data has been collected by various exploration missions over the last decade. These products provide detailed topographic information and are invaluable for scientists to interpret and understand the geological and climate evolution which has occurred on Mars. In order to fully utilise these multi-sensor, multi-resolution and multi-scale Martian topographic products, a co-registration process has been developed which allows co-registration of Digital Terrain Models (DTMs) to be performed to co-align these multiple datasets. Surface matching is the core technique to implement this task and it is here assessed to determine the parameters of the most robust algorithm for DTM co-registration. Once this task was finished, the matching tool was developed accordingly with a decision algorithm. This algorithm was then employed to align DTMs derived from Mars Orbiter Laser Altimeter (MOLA), High Resolution Stereo Camera (HRSC) and High Resolution Imaging Science Experiment (HiRISE). For MOLA and HRSC DTMs, the co-registration was performed directly as the MOLA DTM acted as a reference surface within a bundle adjustment process. DTMs from different versions covering three HRSC orbital strips were used for the assessment process. As a result the mean bias of the height differences of a preliminary version HRSC DTM was significantly reduced from 38.596m to 2.233m, when compared against MOLA while the bias of a newer DTM was improved from 1.616m to 0.161m after matching. Regarding the co-registration of HiRISE and MOLA DTMs, a hierarchical approach employing a HRSC DTM as an intermediate dataset was assessed. The results demonstrated that the method is feasible and that the three DTMs were co-registered effectively. Due to the success highlighted in this paper, a surface matching tool is recommended to be applied to DTMs derived from multiple sources before these data are further used. Moreover, surface matching can be considered as an additional step of any workflow for Mars DTM creation. [Copyright &y& Elsevier]

Abstract: We used Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), High-Resolution Stereo Camera (HRSC), and Observatoire pour la Minéralogie, l''Eau, les Glaces et l''Activité (OMEGA) data to assess the physical and compositional properties of the Malea Planum portion of the Circum-Hellas Volcanic Province (CHVP). Our analysis of surface materials shows that the thermal inertia decreases from north to south, and that there is greater dust cover on the flanks of the CHVP volcanoes than in their putative calderas. Local variations in thermal inertia in Malea Planum are likely due to variations in surface material caused by aeolian and periglacial/permafrost processes, whereas regional variations are likely due to seasonal deposition and sublimation of ice at higher latitudes. Spectral analysis of OMEGA data indicates the widespread presence of pyroxenes and/or olivine, particularly in the rims of craters that likely excavated volcanic materials. Dark materials occur throughout the CHVP, but are concentrated in topographic lows such as crater and caldera floors. Derivation of modal mineralogies from OMEGA data show a variation in composition of dark materials across Malea Planum: eastern dark deposits have higher olivine and low-calcium pyroxene contents, lower high-calcium pyroxene contents, and higher ratios of low-calcium to total pyroxene, relative to western dark deposits. Correlation with cratering-model age estimates suggests that the western deposits are associated with older features (3.8Ga) than the eastern deposits (3.6Ga), but these age differences are within uncertainties. Nevertheless, these results suggest a potential change in composition of volcanic materials in the Malea Planum portion of the CHVP with space, and possibly time. [Copyright &y& Elsevier]

We propose using coupled deep learning based super-resolution restoration (SRR) and single-image digital terrain model (DTM) estimation (SDE) methods to produce subpixel-scale topography from single-view ESA Trace Gas Orbiter Colour and Stereo Surface Imaging System (CaSSIS) and NASA Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (HiRISE) images. We present qualitative and quantitative assessments of the resultant 2 m/pixel CaSSIS SRR DTM mosaic over the ESA and Roscosmos Rosalind Franklin ExoMars rover's (RFEXM22) planned landing site at Oxia Planum. Quantitative evaluation shows SRR improves the effective resolution of the resultant CaSSIS DTM by a factor of 4 or more, while achieving a fairly good height accuracy measured by root mean squared error (1.876 m) and structural similarity (0.607), compared to the ultra-high-resolution HiRISE SRR DTMs at 12.5 cm/pixel. We make available, along with this paper, the resultant CaSSIS SRR image and SRR DTM mosaics, as well as HiRISE full-strip SRR images and SRR DTMs, to support landing site characterisation and future rover engineering for the RFEXM22. [ABSTRACT FROM AUTHOR]

Abstract: The High Resolution Stereo Camera (HRSC) onboard the Mars Express spacecraft in orbit about Mars has four detector channels dedicated to produce images in four spectral channels. Utilizing these spectrophotometric data requires understanding the instrument radiometric calibration and other photometric properties of the data. We present here some results of our investigation into the HRSC color data characteristics. This covers comparison of HRSC measurements with those of telescopes and the Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité (OMEGA) instrument, also on Mars Express. We also investigate the dependence of HRSC Color measurements on solar phase angle and altitude of the Mars surface. These results confirm and extend our earlier findings [McCord, T.B., Adams, J.B., Bellucci, G., Combe, J.-Ph., Hansen, G., Hoffman, H., Jaumann, R., Lumme, K., Neukum, G., Pinet, P., Poulet, F., the HRSC Co-I Team, The Mars Express high Resolution Stereo Camera spectrophotometric data: characteristics and science analysis. J. Geophys. Res. 112, E6, 2007.]. A basic finding from our study is that there are nearly constant offsets between the I/F value derived from the HRSC data and those determined from OMEGA and groundbased telescope measurements, especially in the HRSC red bandpass. These offsets are nearly independent of solar phase angle and Mars surface altitude but are considerably larger for the one comparison at Phobos we were able to make. Several hypotheses could explain these effects: atmospheric scattering, surface photometric effects, shift of the spatial registration or calibration. All these possibilities were investigated. [Copyright &y& Elsevier]

Abstract: The High Resolution Stereo Camera (HRSC) has been orbiting the planet Mars since January 2004 onboard the European Space Agency (ESA) Mars Express mission and delivers imagery which is being used for topographic mapping of the planet. The HRSC team has conducted a systematic inter-comparison of different alternatives for the production of high resolution digital terrain models (DTMs) from the multi look HRSC push broom imagery. Based on carefully chosen test sites the test participants have produced DTMs which have been subsequently analysed in a quantitative and a qualitative manner. This paper reports on the results obtained in this test. [Copyright &y& Elsevier]

Abstract: 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 10m/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 10m/pixel at the nominal periapsis altitude of 250km, with an image swath of 53km, and 2.3m/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 three-dimensional point determination allows the derivation of digital terrain models (DTMs) with a grid size of up to 50m and a height accuracy of a single pixel with up to 10m, 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. [Copyright &y& Elsevier]

Summary: This paper presents an application of object-oriented techniques for habitat classification based on remotely sensed images and ancillary data. The study reports the results of habitat mapping at multiple scales using Earth Observation (EO) data at various spatial resolutions and multi temporal acquisition dates. We investigate the role of object texture and context in classification as well as the value of integrating knowledge from ancillary data sources. Habitat maps were produced at regional and local scales in two case studies; Schleswig-Holstein, Germany and Wye Downs, United Kingdom. At the regional scale, the main task was the development of a consistent object-oriented classification scheme that is transferable to satellite images for other years. This is demonstrated for a time series of Landsat TM/ETM+ scenes. At the local scale, investigations focus on the development of appropriate object-oriented rule networks for the detailed mapping of habitats, e.g. dry grasslands and wetlands using very high resolution satellite and airborne scanner images. The results are evaluated using statistical accuracy assessment and visual comparison with traditional field-based habitat maps. Whereas the application of traditional pixel-based classification result in a pixelised (salt and pepper) representation of land cover, the object-based classification technique result in solid habitat objects allowing easy integration into a vector-GIS for further analysis. The level of detail obtained at the local scale is comparable to that achieved by visual interpretation of aerial photographs or field-based mapping and also retains spatially explicit, fine scale information such as scrub encroachment or ecotone patterns within habitats. [Copyright &y& Elsevier]

The High-Resolution Imaging Science Experiment (HiRISE) onboard the Mars Reconnaissance Orbiter provides remotely sensed imagery at the highest spatial resolution at 25–50 cm/pixel of the surface of Mars. However, due to the spatial resolution being so high, the total area covered by HiRISE targeted stereo acquisitions is very limited. This results in a lack of the availability of high-resolution digital terrain models (DTMs) which are better than 1 m/pixel. Such high-resolution DTMs have always been considered desirable for the international community of planetary scientists to carry out fine-scale geological analysis of the Martian surface. Recently, new deep learning-based techniques that are able to retrieve DTMs from single optical orbital imagery have been developed and applied to single HiRISE observational data. In this paper, we improve upon a previously developed single-image DTM estimation system called MADNet (1.0). We propose optimisations which we collectively call MADNet 2.0, which is based on a supervised image-to-height estimation network, multi-scale DTM reconstruction, and 3D co-alignment processes. In particular, we employ optimised single-scale inference and multi-scale reconstruction (in MADNet 2.0), instead of multi-scale inference and single-scale reconstruction (in MADNet 1.0), to produce more accurate large-scale topographic retrieval with boosted fine-scale resolution. We demonstrate the improvements of the MADNet 2.0 DTMs produced using HiRISE images, in comparison to the MADNet 1.0 DTMs and the published Planetary Data System (PDS) DTMs over the ExoMars Rosalind Franklin rover's landing site at Oxia Planum. Qualitative and quantitative assessments suggest the proposed MADNet 2.0 system is capable of producing pixel-scale DTM retrieval at the same spatial resolution (25 cm/pixel) of the input HiRISE images. [ABSTRACT FROM AUTHOR]

We demonstrate an end-to-end application of the in-house deep learning-based surface modelling system, called MADNet, to produce three large area 3D mapping products from single images taken from the ESA Mars Express's High Resolution Stereo Camera (HRSC), the NASA Mars Reconnaissance Orbiter's Context Camera (CTX), and the High Resolution Imaging Science Experiment (HiRISE) imaging data over the ExoMars 2022 Rosalind Franklin rover's landing site at Oxia Planum on Mars. MADNet takes a single orbital optical image as input, provides pixelwise height predictions, and uses a separate coarse Digital Terrain Model (DTM) as reference, to produce a DTM product from the given input image. Initially, we demonstrate the resultant 25 m/pixel HRSC DTM mosaic covering an area of 197 km × 182 km, providing fine-scale details to the 50 m/pixel HRSC MC-11 level-5 DTM mosaic. Secondly, we demonstrate the resultant 12 m/pixel CTX MADNet DTM mosaic covering a 114 km × 117 km area, showing much more detail in comparison to photogrammetric DTMs produced using the open source in-house developed CASP-GO system. Finally, we demonstrate the resultant 50 cm/pixel HiRISE MADNet DTM mosaic, produced for the first time, covering a 74.3 km × 86.3 km area of the 3-sigma landing ellipse and partially the ExoMars team's geological characterisation area. The resultant MADNet HiRISE DTM mosaic shows fine-scale details superior to existing Planetary Data System (PDS) HiRISE DTMs and covers a larger area that is considered difficult for existing photogrammetry and photoclinometry pipelines to achieve, especially given the current limitations of stereo HiRISE coverage. All of the resultant DTM mosaics are co-aligned with each other, and ultimately with the Mars Global Surveyor's Mars Orbiter Laser Altimeter (MOLA) DTM, providing high spatial and vertical congruence. In this paper, technical details are presented, issues that arose are discussed, along with a visual evaluation and quantitative assessments of the resultant DTM mosaic products. [ABSTRACT FROM AUTHOR]

A seamless mosaic has been constructed including a 3D terrain model at 50 m grid-spacing and a corresponding terrain-corrected orthoimage at 12.5 m using a novel approach applied to ESA Mars Express High Resolution Stereo Camera orbital (HRSC) images of Mars. This method consists of blending and harmonising 3D models and normalising reflectance to a global albedo map. Eleven HRSC image sets were processed to Digital Terrain Models (DTM) based on an opensource stereo photogrammetric package called CASP-GO and merged with 71 published DTMs from the HRSC team. In order to achieve high quality and complete DTM coverage, a new method was developed to combine data derived from different stereo matching approaches to achieve a uniform outcome. This new approach was developed for high-accuracy data fusion of different DTMs at dissimilar grid-spacing and provenance which employs joint 3D and image co-registration, and B-spline fitting against the global Mars Orbiter Laser Altimeter (MOLA) standard reference. Each HRSC strip is normalised against a global albedo map to ensure that the very different lighting conditions could be corrected and resulting in a tiled set of seamless mosaics. The final 3D terrain model is compared against the MOLA height reference and the results shown of this intercomparison both in altitude and planum. Visualisation and access mechanisms to the final open access products are described. [ABSTRACT FROM AUTHOR]