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.

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

<p>The NASA Mars Orbital Laser Altimeter (MOLA) Digital Terrain Model (DTM) has the greatest coverage available for Mars with an average resolution of 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 resolutions finer than 100 m/pixel, and 100% at lower resolutions [2]. Previously, 50m/pixel DTMs were produced 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].</p><p> </p><p>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].</p><p> <br>ACKNOWLEDGEMENT: Part of the research leading to these results has received partial funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n ̊ 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 Alexander Dumke for the exterior orientation processing results used within this research.<br><br>[1] Smith, David, et al. 2001. “Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars.” Journal of Geophysical Research: Planets 106(E10):23689–23722<br><br>[2] Gwinner, et al. 2016. “The High Resolution Stereo Camera (HRSC) of Mars Express and Its Approach to Science Analysis and Mapping for Mars and Its Satellites.” Planetary and Space Science 126:93–138<br><br>[3] Kim and J-P. Muller, 2009. “Multi-resolution topographic data extraction from Martian stereo imagery.” Planetary and Space Science, 57(14-15):2095-2112.<br><br>[4] D. Shin and J-P. Muller, 2012. “Progressively weighted adaptive correlation matching for quasi-dense 3d reconstruction.” Pattern Recognition, 45(10):3795-3809.<br><br>[5] Putri, A.R.D., et al., 2019. “A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express.” Planetary and Space Science.<br><br>[6] Calvin, W.M., et al., 2015. “Interannual and seasonal changes in the north polar ice deposits of Mars: Observations from MY 29–31 using MARCI.” Icarus, 251, pp.181-190.</p><p> </p>

scholarly journals Modeling Streamflow and Sediment Loads with a Photogrammetrically Derived UAS Digital Terrain Model: Empirical Evaluation from a Fluvial Aggregate Excavation Operation

Drones ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 20
Author(s):  
Joseph P. Hupy ◽  
Cyril O. Wilson
Keyword(s):  
Soil Erosion ◽  
Point Cloud ◽  
Empirical Evaluation ◽  
Digital Terrain Model ◽  
Surface Flow ◽  
Sediment Loading ◽  
Terrain Model ◽  
Digital Terrain ◽  
Statistical Measures ◽  
Geospatial Datasets

Soil erosion monitoring is a pivotal exercise at macro through micro landscape levels, which directly informs environmental management at diverse spatial and temporal scales. The monitoring of soil erosion can be an arduous task when completed through ground-based surveys and there are uncertainties associated with the use of large-scale medium resolution image-based digital elevation models for estimating erosion rates. LiDAR derived elevation models have proven effective in modeling erosion, but such data proves costly to obtain, process, and analyze. The proliferation of images and other geospatial datasets generated by unmanned aerial systems (UAS) is increasingly able to reveal additional nuances that traditional geospatial datasets were not able to obtain due to the former’s higher spatial resolution. This study evaluated the efficacy of a UAS derived digital terrain model (DTM) to estimate surface flow and sediment loading in a fluvial aggregate excavation operation in Waukesha County, Wisconsin. A nested scale distributed hydrologic flow and sediment loading model was constructed for the UAS point cloud derived DTM. To evaluate the effectiveness of flow and sediment loading generated by the UAS point cloud derived DTM, a LiDAR derived DTM was used for comparison in consonance with several statistical measures of model efficiency. Results demonstrate that the UAS derived DTM can be used in modeling flow and sediment erosion estimation across space in the absence of a LiDAR-based derived DTM.

scholarly journals Landslides Hazard Assessment Using Different Approaches

2017 ◽  
Vol 13 (2) ◽  
pp. 1-16
Author(s):  
Cristina Coman ◽  
Sanda Manea
Keyword(s):  
Hazard Assessment ◽  
Geographical Area ◽  
Digital Terrain Model ◽  
Seismic Action ◽  
Hazard Maps ◽  
Terrain Model ◽  
North East ◽  
The North ◽  
Digital Terrain ◽  
Natural Slopes

AbstractRomania represents one of Europe’s countries with high landslides occurrence frequency. Landslide hazard maps are designed by considering the interaction of several factors which, by their joint action may affect the equilibrium state of the natural slopes. The aim of this paper is landslides hazard assessment using the methodology provided by the Romanian national legislation and a very largely used statistical method. The final results of these two analyses are quantitative or semi-quantitative landslides hazard maps, created in geographic information system environment. The data base used for this purpose includes: geological and hydrogeological data, digital terrain model, hydrological data, land use, seismic action, anthropic action and an inventory of active landslides. The GIS landslides hazard models were built for the geographical area of the Iasi city, located in the north-east side of Romania.

Morphometry of volcanic cones on Mars in perspective of Astrobiological Research

2015 ◽  
Vol 14 (4) ◽  
pp. 537-545 ◽  
Author(s):  
Michael Gilichinsky ◽  
Nikita Demidov ◽  
Elizaveta Rivkina
Keyword(s):  
Morphometric Analysis ◽  
Digital Terrain Model ◽  
Basal Area ◽  
Kamchatka Peninsula ◽  
Width Ratio ◽  
Cinder Cones ◽  
Terrain Model ◽  
The North ◽  
Digital Terrain ◽  
North Polar

AbstractThe permanently frozen volcanic sediment is one of the most promising geological objects for searching life on Mars. On Earth, volcanic intrusions into permafrost result in formation of the unique microbial communities. We propose several terrestrial analogues of Martian polar volcanoes, such as the permanently frozen volcanic sediments on the Kamchatka peninsula and in Antarctica. The present study shows applicability of the morphometric analysis for demonstration of the morphological similarity between the terrestrial and Martian cinder cones. In the present work, the morphometric analysis of young Martian landforms is based on the assumption that the conical structures identified on digital terrain model (DTM) are volcanic cinder cones. Morphometric analysis of the studied cones showed a range of degradation. The extent of degradation may be an indicator of age based on comparison with volcanic cinder cones on Earth. A morphometric analysis of potentially young volcanic cones in the North Polar Region of Mars was performed to estimate their relative age. The 14 potential cinder cones were identified using the DTM provided by Mars Express High Resolution Stereo Camera (HRSC), allowing for the basic morphometric calculations. The majority of the cinder cones are localized in the Chasma Boreale region within the area 79°–81°N and 261°–295°E. The calculated morphometric parameters showed that the cone average steepness varied from 3.4° to 11.8°, cone height-to-width ratio varied from 0.025 to 0.12, and the ratio between surface and basal area of the cone varied from 1.005 to 1.131. The studied cinder cones were classified with respect to the morphometric ratios assuming that larger values correspond to the younger structures. Employing the terrestrial analogy of morphometric ratios as a proxy for relative geological age, we suggest that existing microorganisms may be found in permafrost of young Martian cinder cones.

scholarly journals Digital Terrain Model Derivatives Analysis with the Aim of Identifying Specific Soil Types in Young Post-Glacial Topography with a Vector Approach

2021 ◽  
Vol 54 (1) ◽  
pp. 123
Author(s):  
Małgorzata Radło-Kulisiewicz
Keyword(s):  
Digital Terrain Model ◽  
Spatial Location ◽  
Soil Mapping ◽  
Soil Types ◽  
Font Size ◽  
Terrain Model ◽  
North East ◽  
The North ◽  
Digital Terrain ◽  
Starting Point

<p>This article discusses a study conducted in order to analyse selected Digital Terrain Model (DTM) derivates in  diverse young post-glacial topographic profiles  with the aim of identifying terrain features that could be related to the soils that formed there. The area under investigation is within the reach of the youngest Vistulian Glaciation, in the north-east of Poland. The main goal of the study was to reveal indirect relationships between a lithological soil type and terrain forms, which transpire from DTM derivatives. This can directly help to assign the type of soil in the area to one of the three soil types: a) made of sand, b) made of loam, c) wet-soils. <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">The starting point for<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> the research undertaken was the landscape approach to soil modelling and the article deals with<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> medium scales. </span></span></span>Derivatives were analysed using vector data notation, focusing on selected derivative values and their spatial location in relation to one another. The results obtained indicate the possibility of using this approach as an auxiliary approach in soil mapping of areas for which the quality of source materials (such as precipitation geometry) is low. Thus, they can be of assistance in improving the existing soil maps of selected scales. The trend revealed in the obtained results of DTM analysis can be considered as a contribution to realisation of assumptions of a study in digital soil mapping with the use of selected methods of AI.</p>

scholarly journals Medieval Archaeology Under the Canopy with LiDAR. The (Re)Discovery of a Medieval Fortified Settlement in Southern Italy

2018 ◽  
Vol 10 (10) ◽  
pp. 1598 ◽  
Author(s):  
Nicola Masini ◽  
Fabrizio Gizzi ◽  
Marilisa Biscione ◽  
Vincenzo Fundone ◽  
Michele Sedile ◽  
...  
Keyword(s):  
Middle Ages ◽  
Southern Italy ◽  
Digital Terrain Model ◽  
Maximum Information ◽  
Archaeological Prospection ◽  
Terrain Model ◽  
The North ◽  
Digital Terrain ◽  
Visualization Techniques ◽  
Medieval Archaeology

Despite the recognized effectiveness of LiDAR in penetrating forest canopies, its capability for archaeological prospection can be strongly limited in areas covered by dense vegetation for the detection of subtle remains scattered over morphologically complex areas. In these cases, an important contribution to improve the identification of topographic variations of archaeological interest is provided by LiDAR-derived models (LDMs) based on relief visualization techniques. In this paper, diverse LDMs were applied to the medieval site of Torre Cisterna to the north of Melfi (Southern Italy), selected for this study because it is located on a hilly area with complex topography and thick vegetation cover. These conditions are common in several places of the Apennines in Southern Italy and prevented investigations during the 20th century. Diverse LDMs were used to obtain maximum information and to compare the performance of both subjective (through visual inspections) and objective (through their automatic classification) methods. To improve the discrimination/extraction capability of archaeological micro-relief, noise filtering was applied to Digital Terrain Model (DTM) before obtaining the LDMs. The automatic procedure allowed us to extract the most significant and typical features of a fortified settlement, such as the city walls and a tower castle. Other small, subtle features attributable to possible buried buildings of a habitation area have been identified by visual inspection of LDMs. Field surveys and in-situ inspections were carried out to verify the archaeological points of interest, microtopographical features, and landforms observed from the DTM-derived models, most of them automatically extracted. As a whole, the investigations allowed (i) the rediscovery of a fortified settlement from the 11th century and (ii) the detection of an unknown urban area abandoned in the Middle Ages.

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.

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.

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