scholarly journals Seamless 3D Image Mapping and Mosaicing of Valles Marineris on Mars Using Orbital HRSC Stereo and Panchromatic Images

2021 ◽  
Vol 13 (7) ◽  
pp. 1385
Author(s):  
Yu Tao ◽  
Greg Michael ◽  
Jan-Peter Muller ◽  
Susan J. Conway ◽  
Alfiah R. D. Putri
Keyword(s):  
Stereo Matching ◽  
3D Models ◽  
Grid Spacing ◽  
Laser Altimeter ◽  
Terrain Model ◽  
Valles Marineris ◽  
Digital Terrain ◽  
3D Terrain ◽  
Spline Fitting ◽  
Novel Approach

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.

scholarly journals Hemispherical differences in the shape and topography of asteroid (101955) Bennu

2020 ◽  
Vol 6 (41) ◽  
pp. eabd3649 ◽  
Author(s):  
M. G. Daly ◽  
O. S. Barnouin ◽  
J. A. Seabrook ◽  
J. Roberts ◽  
C. Dickinson ◽  
...  
Keyword(s):  
Digital Terrain Model ◽  
Surface Flow ◽  
Altimeter Data ◽  
Asymmetric Distribution ◽  
The South ◽  
Laser Altimeter ◽  
Terrain Model ◽  
The North ◽  
Digital Terrain ◽  
Northern And Southern Hemispheres

We investigate the shape of near-Earth asteroid (101955) Bennu by constructing a high-resolution (20 cm) global digital terrain model from laser altimeter data. By modeling the northern and southern hemispheres separately, we find that longitudinal ridges previously identified in the north extend into the south but are obscured there by surface material. In the south, more numerous large boulders effectively retain surface materials and imply a higher average strength at depth to support them. The north has fewer large boulders and more evidence of boulder dynamics (toppling and downslope movement) and surface flow. These factors result in Bennu’s southern hemisphere being rounder and smoother, whereas its northern hemisphere has higher slopes and a less regular shape. We infer an originally asymmetric distribution of large boulders followed by a partial disruption, leading to wedge formation in Bennu’s history.

scholarly journals Workflow for 3D geovisualization of the data obtained with the use of Unmanned Aerial Vehicle in Augmented Reality

2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Łukasz Halik ◽  
Maciej Smaczyński ◽  
Beata Medyńska-Gulij
Keyword(s):  
Augmented Reality ◽  
Large Scale ◽  
3D Model ◽  
Digital Terrain Model ◽  
Point Clouds ◽  
3D Models ◽  
Irregular Shape ◽  
Terrain Model ◽  
Natural Aggregate ◽  
Digital Terrain

<p><strong>Abstract.</strong> The attempt to work out the geomatic workflow of transforming low-level aerial imagery obtained with unmanned aerial vehicles (UAV) into a digital terrain model (DTM) and implementing the 3D model into the augmented reality (AR) system constitutes the main problem discussed in this article. The authors suggest the following workflow demonstrated in Fig. 1.</p><p>The series of pictures obtained by means of UAV equipped with a HD camera was the source of data to be worked out in the final stage of the geovisualization. The series was then processed and a few point clouds were isolated from it, being later used for generating test 3D models.</p><p>The practical aim of the research conducted was to work out, on the basis of the UAV pictures, the 3D geovisualization in the AR system that would depict the heap of the natural aggregate of irregular shape. The subsequent aim was to verify the accuracy of the produced 3D model. The object of the study was a natural aggregate heap of irregular shape and denivelations up to 11 meters.</p><p>Based on the obtained photos, three point clouds (varying in the level of detail) were generated for the 20&amp;thinsp;000-meter-square area. The several-centimeter differences observed between the control points in the field and the ones from the model might corroborate the usefulness of the described algorithm for creating large-scale DTMs for engineering purposes. The method of transformation of pictures into the point cloud that was subsequently transformed into 3D models was employed in the research, resulting in the scheme depicting the technological sequence of the creation of 3D geovisualization worked out in the AR system. The geovisualization can be viewed thanks to a specially worked out mobile application for smartphones.</p>

HRSC 3D Image products of the North Polar Layered Terrain of Mars

2020 ◽  
Author(s):  
Alfiah Rizky Diana Putri ◽  
Yu Tao ◽  
Jan-Peter Muller
Keyword(s):  
High Resolution ◽  
Digital Terrain Model ◽  
Space Science ◽  
Laser Altimeter ◽  
Mars Express ◽  
Stereo Camera ◽  
Terrain Model ◽  
The North ◽  
Digital Terrain ◽  
North Polar

&lt;p&gt;The NASA Mars Orbital Laser Altimeter (MOLA) Digital Terrain Model (DTM) has the greatest coverage available for Mars with an average resolution of&amp;#160;463 m/pixel (128pixel/ degree) globally and 112 m/ pixel (512 pixels/degree) for the polar regions [1]. The ESA Mars Express High-Resolution Stereo Camera (HRSC) is currently orbiting Mars and continuously mapping the surface, 98% with&amp;#160;resolutions finer than 100 m/pixel, and 100% at lower resolutions [2]. Previously,&amp;#160;50m/pixel DTMs were produced&amp;#160;using a NASA-VICAR-based pipeline developed by the German Aerospace Centre, with modifications from Kim and Muller [3] for the south polar region, using an image matcher based on the Gruen-Otto-Chau (Gotcha) algorithm [4].&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In this research, we demonstrate application of the same method to the North Polar [5] region. Forty single strip DTMs have been processed and corrected to produce a north polar HRSC DTM mosaic at 50m/pixel. The assessment of the dataset to MOLA will be discussed. Moreover, a large number (~50) of the North polar HRSC images are co-registered and orthorectified using the DTM mosaic. We also demonstrate observations of the seasonal ice cap growth and retreat using the orthorectified images for Martian Year (MY) 27-32. In addition, the results for MY28-31 are compared against the observations from the Mars Colour Imager (MARCI)[6].&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;br&gt;ACKNOWLEDGEMENT:&amp;#160;Part of the research leading to these results has received partial funding from the European Union&amp;#8217;s Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n &amp;#778;&amp;#160;607379; The first author is supported by the Indonesian Endowment Fund for Education. We would also like to express gratitude to the HRSC team and the MOLA team for the usage of HRSC and MOLA data, and&amp;#160;Alexander Dumke for the exterior orientation processing results used within this research.&lt;br&gt;&lt;br&gt;[1] Smith, David, et al. 2001. &amp;#8220;Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars.&amp;#8221; Journal of Geophysical Research: Planets 106(E10):23689&amp;#8211;23722&lt;br&gt;&lt;br&gt;[2] Gwinner, et al. 2016. &amp;#8220;The High Resolution Stereo Camera (HRSC) of Mars Express and Its Approach to Science Analysis and Mapping for Mars and Its Satellites.&amp;#8221; Planetary and Space Science 126:93&amp;#8211;138&lt;br&gt;&lt;br&gt;[3] Kim and J-P. Muller, 2009. &amp;#8220;Multi-resolution topographic data extraction from Martian stereo imagery.&amp;#8221; Planetary and Space Science, 57(14-15):2095-2112.&lt;br&gt;&lt;br&gt;[4] D. Shin and J-P. Muller, 2012. &amp;#8220;Progressively weighted adaptive correlation matching for quasi-dense 3d reconstruction.&amp;#8221; Pattern Recognition, 45(10):3795-3809.&lt;br&gt;&lt;br&gt;[5] Putri, A.R.D., et al., 2019. &amp;#8220;A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express.&amp;#8221; Planetary and Space Science.&lt;br&gt;&lt;br&gt;[6] Calvin, W.M., et al., 2015. &amp;#8220;Interannual and seasonal changes in the north polar ice deposits of Mars: Observations from MY 29&amp;#8211;31 using MARCI.&amp;#8221; Icarus, 251, pp.181-190.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Assessing the Performance of ICESat-2/ATLAS Multi-Channel Photon Data for Estimating Ground Topography in Forested Terrain

2020 ◽  
Vol 12 (13) ◽  
pp. 2084
Author(s):  
Yanqiu Xing ◽  
Jiapeng Huang ◽  
Armin Gruen ◽  
Lei Qin
Keyword(s):  
Mean Squared Error ◽  
Photon Counting ◽  
Digital Terrain Model ◽  
Airborne Lidar ◽  
Coefficient Of Determination ◽  
Laser Altimeter ◽  
Terrain Model ◽  
Vegetation Height ◽  
Counting Approach ◽  
Digital Terrain

As a continuation of Ice, Cloud, and Land Elevation Satellite-1 (ICESat-1), the ICESat-2/Advanced Topographic Laser Altimeter System (ATLAS) employs a micro-pulse multi-beam photon counting approach to produce photon data for measuring global terrain. Few studies have assessed the accuracy of different ATLAS channels in retrieving ground topography in forested terrain. This study aims to assess the accuracy of measuring ground topography in forested terrain using different ATLAS channels and the correlation between laser intensity parameters, laser pointing angle parameters, and elevation error. The accuracy of ground topography measured by the ATLAS footprints is evaluated by comparing the derived Digital Terrain Model (DTM) from the ATL03 (Global Geolocated Photon Data) and ATL08 (Land and Vegetation Height) products with that from the airborne Light Detection And Ranging (LiDAR). Results show that the ATLAS product performed well in the study area at all laser intensities and laser pointing angles, and correlations were found between the ATLAS DTM and airborne LiDAR DTM (coefficient of determination––R2 = 1.00, root mean squared error––RMSE = 0.75 m). Considering different laser intensities, there is a significant correlation between the tx_pulse_energy parameter and elevation error. With different laser pointing angles, there is no significant correlation between the tx_pulse_skew_est, tx_pulse_width_lower, tx_pulse_width_upper parameters and the elevation error.

3D multi-resolution mapping of Valles Marineris for better understanding of RSL formation

2020 ◽  
Author(s):  
Yu Tao ◽  
Jan-Peter Muller ◽  
Susan Conway
Keyword(s):  
High Resolution ◽  
Liquid Water ◽  
Imaging System ◽  
Laser Altimeter ◽  
Imaging Spectrometer ◽  
Valles Marineris ◽  
Digital Terrain ◽  
Imaging Science ◽  
Resolution Mapping ◽  
Recurring Slope Lineae

&lt;p&gt;Recurring Slope Lineae (RSLs) are metre- to decametre-wide dark streaks found on steep slopes, which lengthen downslope during the warmest times of the year, fading during the cooler periods and reappearing again in the next Martian year. This behaviour has been linked to the action of liquid water, but as liquid water is thermodynamically unstable under current martian conditions this interpretation is under vigorous debate. A better understanding of the formation process of RSLs is therefore fundamental to constraining Mars&amp;#8217; water budget and habitability. One of the key components for studying the RSL process is accurate knowledge of the slopes and aspects.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The Valles Marineris (VM) area has the highest concentration of RSLs found on Mars as well as being a location where the triple point of water can be reached during the Martian summertime. This study focuses on multi-resolution 3D mapping of the whole VM area with all digital terrain models (DTMs) vertically referenced to the global standard Mars Orbiter Laser Altimeter (MOLA) surface. A multi-resolution DTM has been generated consisting of 82 Mars Express High Resolution Camera (HRSC) 50m DTMs and 1763 Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) 18m DTMs which will be presented. For 3 selected study areas (Coprates Montes, Capri Mensa, Nectaris Montes), terrain corrected and co-registered MRO High Resolution Imaging Science Experiment (HiRISE; at 0.25m), Compact Reconnaissance Imaging Spectrometer for Mars (CRISM; at 20/50m) and ExoMars Trace Gas Orbiter (TGO) Colour and Stereo Surface Imaging System (CaSSIS; at 2.5m) colour images and associated DTMs will be discussed.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;The research leading to these results is receiving funding from the UKSA Aurora programme (2018-2021) under grant no. ST/S001891/1.&lt;/p&gt;

scholarly journals The Effect of LiDAR Sampling Density on DTM Accuracy for Areas with Heavy Forest Cover

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 265
Author(s):  
Mihnea Cățeanu ◽  
Arcadie Ciubotaru
Keyword(s):  
Forest Cover ◽  
Initial Point ◽  
Ground Surface ◽  
Digital Terrain Model ◽  
Morphological Data ◽  
Sampling Density ◽  
Terrain Model ◽  
Digital Terrain ◽  
Point Density ◽  
The Impact

Laser scanning via LiDAR is a powerful technique for collecting data necessary for Digital Terrain Model (DTM) generation, even in densely forested areas. LiDAR observations located at the ground level can be separated from the initial point cloud and used as input for the generation of a Digital Terrain Model (DTM) via interpolation. This paper proposes a quantitative analysis of the accuracy of DTMs (and derived slope maps) obtained from LiDAR data and is focused on conditions common to most forestry activities (rough, steep terrain with forest cover). Three interpolation algorithms were tested: Inverse Distance Weighted (IDW), Natural Neighbour (NN) and Thin-Plate Spline (TPS). Research was mainly focused on the issue of point data density. To analyze its impact on the quality of ground surface modelling, the density of the filtered data set was artificially lowered (from 0.89 to 0.09 points/m2) by randomly removing point observations in 10% increments. This provides a comprehensive method of evaluating the impact of LiDAR ground point density on DTM accuracy. While the reduction of point density leads to a less accurate DTM in all cases (as expected), the exact pattern varies by algorithm. The accuracy of the LiDAR-derived DTMs is relatively good even when LiDAR sampling density is reduced to 0.40–0.50 points/m2 (50–60 % of the initial point density), as long as a suitable interpolation algorithm is used (as IDW proved to be less resilient to density reductions below approximately 0.60 points/m2). In the case of slope estimation, the pattern is relatively similar, except the difference in accuracy between IDW and the other two algorithms is even more pronounced than in the case of DTM accuracy. Based on this research, we conclude that LiDAR is an adequate method for collecting morphological data necessary for modelling the ground surface, even when the sampling density is significantly reduced.

scholarly journals DTM-based analysis of the spatial distribution of topolineaments

2020 ◽  
Vol 12 (1) ◽  
pp. 1185-1199
Author(s):  
Mirosław Kamiński
Keyword(s):  
Laser Scanning ◽  
Digital Terrain Model ◽  
Research Area ◽  
Tectonic Structures ◽  
Empirical Bayesian ◽  
Scanning Method ◽  
Empirical Bayesian Kriging ◽  
Terrain Model ◽  
Digital Terrain ◽  
Airborne Laser

AbstractThe research area is located on the boundary between two Paleozoic structural units: the Radom–Kraśnik Block and the Mazovian–Lublin Basin in the southeastern Poland. The tectonic structures are separated by the Ursynów–Kazimierz Dolny fault zone. The digital terrain model obtained by the ALS (Airborne Laser Scanning) method was used. Classification and filtration of an elevation point cloud were performed. Then, from the elevation points representing only surfaces, a digital terrain model was generated. The model was used to visually interpret the course of topolineaments and their automatic extraction from DTM. Two topolineament systems, trending NE–SW and NW–SE, were interpreted. Using the kernel density algorithm, topolineament density models were generated. Using the Empirical Bayesian Kriging, a thickness model of quaternary deposits was generated. A relationship was observed between the course of topolineaments and the distribution and thickness of Quaternary formations. The topolineaments were compared with fault directions marked on tectonic maps of the Paleozoic and Mesozoic. Data validation showed consistency between topolineaments and tectonic faults. The obtained results are encouraging for further research.

scholarly journals Production, Validation and Morphometric Analysis of a Digital Terrain Model for Lake Trichonis Using Geospatial Technologies and Hydroacoustics

2021 ◽  
Vol 10 (2) ◽  
pp. 91
Author(s):  
Triantafyllia-Maria Perivolioti ◽  
Antonios Mouratidis ◽  
Dimitrios Terzopoulos ◽  
Panagiotis Kalaitzis ◽  
Dimitrios Ampatzidis ◽  
...  
Keyword(s):  
Morphometric Analysis ◽  
Ad Hoc ◽  
Regional Scale ◽  
Digital Terrain Model ◽  
Relevant Information ◽  
Relative Difference ◽  
Systematic Observation ◽  
Qualitative And Quantitative ◽  
Terrain Model ◽  
Digital Terrain

Covering an area of approximately 97 km2 and with a maximum depth of 58 m, Lake Trichonis is the largest and one of the deepest natural lakes in Greece. As such, it constitutes an important ecosystem and freshwater reserve at the regional scale, whose qualitative and quantitative properties ought to be monitored. Depth is a crucial parameter, as it is involved in both qualitative and quantitative monitoring aspects. Thus, the availability of a bathymetric model and a reliable DTM (Digital Terrain Model) of such an inland water body is imperative for almost any systematic observation scenario or ad hoc measurement endeavor. In this context, the purpose of this study is to produce a DTM from the only official cartographic source of relevant information available (dating back approximately 70 years) and evaluate its performance against new, independent, high-accuracy hydroacoustic recordings. The validation procedure involves the use of echosoundings coupled with GPS, and is followed by the production of a bathymetric model for the assessment of the discrepancies between the DTM and the measurements, along with the relevant morphometric analysis. Both the production and validation of the DTM are conducted in a GIS environment. The results indicate substantial discrepancies between the old DTM and contemporary acoustic data. A significant overall deviation of 3.39 ± 5.26 m in absolute bottom elevation differences and 0.00 ± 7.26 m in relative difference residuals (0.00 ± 2.11 m after 2nd polynomial model corrector surface fit) of the 2019 bathymetric dataset with respect to the ~1950 lake DTM and overall morphometry appear to be associated with a combination of tectonics, subsidence and karstic phenomena in the area. These observations could prove useful for the tectonics, geodynamics and seismicity with respect to the broader Corinth Rift region, as well as for environmental management and technical interventions in and around the lake. This dictates the necessity for new, extensive bathymetric measurements in order to produce an updated DTM of Lake Trichonis, reflecting current conditions and tailored to contemporary accuracy standards and state-of-the-art research in various disciplines in and around the lake.

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