scholarly journals Comment on “Objective extraction of channel heads from high-resolution topographic data” by Fiona J. Clubb et al.

2015 ◽  
Vol 51 (2) ◽  
pp. 1372-1376 ◽  
Author(s):  
Paola Passalacqua ◽  
Efi Foufoula-Georgiou
Keyword(s):  
High Resolution ◽  
Topographic Data

scholarly journals Reading the bed morphology of a mountain stream: a geomorphometric study on high-resolution topographic data

2010 ◽  
Vol 14 (2) ◽  
pp. 393-405 ◽  
Author(s):  
S. Trevisani ◽  
M. Cavalli ◽  
L. Marchi
Keyword(s):  
High Resolution ◽  
Ad Hoc ◽  
Flow Direction ◽  
Spatial Scales ◽  
Mountain Stream ◽  
Topographic Data ◽  
The Difference ◽  
Morphological Differences ◽  
High Level ◽  
Local Anomalies

Abstract. High-resolution topographic data expand the potential of quantitative analysis of the earth surface, improving the interpretation of geomorphic processes. In particular, the morphologies of the channel beds of mountain streams, which are characterised by strong spatial variability, can be analysed much more effectively with this type of data. In this study, we analysed the aerial LiDAR topographic data of a headwater stream, the Rio Cordon (watershed area: 5 km2), located in the Dolomites (north-eastern Italy). The morphology of the channel bed of Rio Cordon is characterised by alternating step pools, cascades, and rapids with steps. We analysed the streambed morphology by means of ad hoc developed morphometric indices, capable of highlighting morphological features at a high level of spatial resolution. To perform the analysis and the data interpolation, we carried out a channel-oriented coordinate transformation. In the new coordinate system, the calculation of morphometric indices in directions along and transverse to the flow direction is straightforward. Three geomorphometric indices were developed and applied as follows: a slope index computed on the whole width of the channel bed, directional variograms computed along the flow direction and perpendicular to it, and local anomalies, calculated as the difference between directional variograms at different spatial scales. Directional variograms in the flow direction and local anomalies have proven to be effective at recognising morphologic units, such as steps, pools and clusters of large boulders. At the spatial scale of channel reaches, these indices have demonstrated a satisfactory capability to outline patterns associated with boulder cascades and rapids with steps, whereas they did not clearly differentiate between morphologies with less marked morphological differences, such as step pools and cascades.

High-Resolution Digital Elevation and Bathymetry Model for Tsunami Run-Up and Inundation Simulation in Penang

2019 ◽  
Vol 13 (05n06) ◽  
pp. 1941001
Author(s):  
Su Yean Teh ◽  
Hock Lye Koh ◽  
Yong Hui Lim
Keyword(s):  
High Resolution ◽  
Indian Ocean ◽  
Sea Level ◽  
Interpolation Method ◽  
Topographic Maps ◽  
Seamless Integration ◽  
Topographic Data ◽  
Digital Elevation ◽  
Run Up ◽  
Tsunami Run Up

Many beaches in Penang island were severely inundated by the 26 December 2004 Indian Ocean mega tsunami with 57 deaths recorded. It is anticipated that the next big tsunami will cause even more damages to beaches in Penang. Hence, developing community resilience against the risks of the next tsunami is essential. Resilience entails many interlinked components, beginning with a good understanding of the inundation scenarios critical to community evacuation and resilience preparation. Inundation scenarios are developed from tsunami simulations involving all three phases of tsunami generation, propagation and run-up. Accurate and high-resolution bathymetric–topographic maps are essential for simulations of tsunami wave inundation along beaches. Bathymetric maps contain information on the depths of landforms below sea level while topographic maps reveal the elevation of landforms above sea level. Bathymetric and topographic datasets for Malaysia are, however, currently not integrated and are available separately and in different formats, not suitable for inundation simulations. Bathymetric data are controlled by the National Hydrographic Centre (NHC) of the Royal Malaysian Navy while topographic data are serviced by the Department of Survey and Mapping Malaysia (JUPEM). It is highly desirable to have seamless integration of high-resolution bathymetric and topographic data for tsunami simulations and for other scientific studies. In this paper, we develop a robust method for integrating the NHC bathymetric and JUPEM topographic data into a regularly-spaced grid system essential for tsunami simulation. A primary objective of this paper is to develop the best Digital Elevation and Bathymetry Model (DEBM) for Penang based upon the most suitable and accurate interpolation method for integrating bathymetric and topographic data with minimal interpolation errors. We analyze four commonly used interpolation methods for generating gridded topographic and bathymetric surfaces, namely (i) Kriging, (ii) Multiquadric (MQ), (iii) Thin Plate Spline (TPS) and (iv) Inverse Distance to Power (IDP). The study illustrated that the Kriging interpolation method produces an integrated bathymetric and topographic surface that best approximates the admiralty nautical chart of Penang essential for tsunami run-up and inundation simulations. Tsunami inundation scenarios critical to risk analysis and mitigation could then be developed using this DEBM for various earthquake scenarios, as presented in this paper for the 2004 Indian Ocean Tsunami.

scholarly journals Global Sensitivity Analysis with 2D Hydraulic Codes: Application on Uncertainties Related to High-Resolution Topographic Data

2015 ◽  
pp. 301-315 ◽  
Author(s):  
Morgan Abily ◽  
Olivier Delestre ◽  
Philippe Gourbesville ◽  
Nathalie Bertrand ◽  
Claire-Marie Duluc ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
High Resolution ◽  
Global Sensitivity Analysis ◽  
Global Sensitivity ◽  
Topographic Data

scholarly journals Using kites for 3-D mapping of gullies at decimetre-resolution over several square kilometres: a case study on the Kamech catchment, Tunisia

2018 ◽  
Vol 18 (6) ◽  
pp. 1567-1582 ◽  
Author(s):  
Denis Feurer ◽  
Olivier Planchon ◽  
Mohamed Amine El Maaoui ◽  
Abir Ben Slimane ◽  
Mohamed Rached Boussema ◽  
...  
Keyword(s):  
High Resolution ◽  
Aerial Photography ◽  
Airborne Lidar ◽  
Data Set ◽  
Topographic Data ◽  
Independent Field ◽  
Wide Range ◽  
Laser Systems ◽  
High Level

Abstract. Monitoring agricultural areas threatened by soil erosion often requires decimetre topographic information over areas of several square kilometres. Airborne lidar and remotely piloted aircraft system (RPAS) imagery have the ability to provide repeated decimetre-resolution and -accuracy digital elevation models (DEMs) covering these extents, which is unrealistic with ground surveys. However, various factors hamper the dissemination of these technologies in a wide range of situations, including local regulations for RPAS and the cost for airborne laser systems and medium-format RPAS imagery. The goal of this study is to investigate the ability of low-tech kite aerial photography to obtain DEMs with decimetre resolution and accuracy that permit 3-D descriptions of active gullying in cultivated areas of several square kilometres. To this end, we developed and assessed a two-step workflow. First, we used both heuristic experimental approaches in field and numerical simulations to determine the conditions that make a photogrammetric flight possible and effective over several square kilometres with a kite and a consumer-grade camera. Second, we mapped and characterised the entire gully system of a test catchment in 3-D. We showed numerically and experimentally that using a thin and light line for the kite is key for a complete 3-D coverage over several square kilometres. We thus obtained a decimetre-resolution DEM covering 3.18 km2 with a mean error and standard deviation of the error of +7 and 22 cm respectively, hence achieving decimetre accuracy. With this data set, we showed that high-resolution topographic data permit both the detection and characterisation of an entire gully system with a high level of detail and an overall accuracy of 74 % compared to an independent field survey. Kite aerial photography with simple but appropriate equipment is hence an alternative tool that has been proven to be valuable for surveying gullies with sub-metric details in a square-kilometre-scale catchment. This case study suggests that access to high-resolution topographic data on these scales can be given to the community, which may help facilitate a better understanding of gullying processes within a broader spectrum of conditions.

Evaluation of the sensitivity of open source DEM vs. local high resolution DEM data in tsunami hazard assessment

2020 ◽  
Author(s):  
Duygu Tufekci-Enginar ◽  
M. Lutfi Suzen ◽  
G. Guney Dogan ◽  
Ahmet Cevdet Yalciner
Keyword(s):  
High Resolution ◽  
Open Source ◽  
Spatial Resolution ◽  
Hazard Assessment ◽  
Tsunami Hazard ◽  
Quality Data ◽  
Topographic Data ◽  
Aster Gdem ◽  
Tsunami Hazard Assessment ◽  
Topography Data

<p>Tsunami simulations using high resolution datasets would always resemble the results that are closer to the reality. However, high resolution airborne or spaceborne local datasets have not yet been available for many regions and acquisition of this data is costly or might not even be possible for some locations. This hard-to-reach situation of high resolution datasets obliged researchers to work with open source datasets in their studies, which forces them to cope with the uncertainties of low spatial resolution.</p><p>Tsunami numerical models require both bathymetric and topographic data in order to calculate wave propagation in the water and inundation on the land. Leaving aside the availability of reliable bathymetric data, there are different open source global Digital Elevation Model (DEM) datasets, which are freely available. ASTER GDEM, SRTM and ALOS World 3D are present global open source DEMs that have highest spatial resolution of 30 meters. These three different sources of DEMs are generated using different technologies during data acquisition and different methodologies while processing. Even if they are the best available open source datasets, they all include variable sources of differences and errors.</p><p>This study aims evaluation of the sensitivity of open source DEM datasets against high resolution DEM datasets for tsunami hazard assessment and examination of accuracy of the simulations’ results. A small area in Silivri district of Istanbul is selected as study area, where 1m resolution of topographic data is available. Tsunami simulations are performed using NAMI DANCE GPU with topography data of 1m resolution based on LiDAR measurements and topography data of 30m resolution based on ASTER GDEM, SRTM and ALOS World 3D datasets. The resulted inundation on land and flow depth distributions are plotted and discussed with comparisons.</p><p> </p><p>Acknowledgement: MSc. Bora Yalciner and Assoc. Prof. Dr. Andrey Zaytsev are acknowledged for their contributions in developing tsunami numerical model NAMI DANCE GPU used in this study. The authors also thank Istanbul Metropolitan Municipality, Directorate of Earthquake and Ground Investigation for providing high quality data and close cooperation.</p><p>Keywords: tsunami, hazard assessment, numerical modeling, open source DEM, high-resolution DEM</p>

scholarly journals Reading the bed morphology of a mountain stream: a geomorphometric study on high-resolution topographic data

2009 ◽  
Vol 6 (6) ◽  
pp. 7287-7319 ◽  
Author(s):  
S. Trevisani ◽  
M. Cavalli ◽  
L. Marchi
Keyword(s):  
High Resolution ◽  
Ad Hoc ◽  
Flow Direction ◽  
Spatial Scales ◽  
Mountain Stream ◽  
Topographic Data ◽  
The Difference ◽  
Morphological Differences ◽  
High Level ◽  
Local Anomalies

Abstract. High-resolution topographic data expand the potential of quantitative analysis of the earth surface, improving the interpretation of geomorphic processes. In particular, the morphologies of the channel beds of mountain streams, which are characterised by strong spatial variability, can be analysed much more effectively with this type of data. In the present study, we analysed the aerial LiDAR topographic data of a headwater stream, the Rio Cordon (watershed area: 5 km2), located in the Dolomites (north-eastern Italy). The morphology of the channel bed of Rio Cordon is characterised by alternating step pools, cascades, and rapids with steps. We analysed the streambed morphology by means of ad hoc developed morphometric indices, capable of highlighting morphological features at a high level of spatial resolution. To perform the analysis and the data interpolation, we carried out a channel-oriented coordinate transformation. In the new coordinate system, the calculation of morphometric indices in directions along and transverse to the flow direction is straightforward. Three geomorphometric indices were developed and applied as follows: a slope index computed along the whole width of the channel bed, directional variograms computed along the flow direction and perpendicular to it, and local anomalies, calculated as the difference between directional variograms at different spatial scales. Directional variograms in the flow direction and local anomalies have proven to be effective at recognising morphologic units, such as steps, pools and clusters of large boulders. At the spatial scale of channel reaches, these indices have demonstrated a satisfactory capability to outline patterns associated with boulder cascades and rapids with steps, whereas they did not clearly differentiate between morphologies with less marked morphological differences, such as step pools and cascades.

scholarly journals A method based on structure-from-motion photogrammetry to generate sub-millimetre-resolution digital elevation models for investigating rock breakdown features

2019 ◽  
Vol 7 (1) ◽  
pp. 45-66 ◽  
Author(s):  
Ankit Kumar Verma ◽  
Mary Carol Bourke
Keyword(s):  
High Resolution ◽  
Structure From Motion ◽  
Low Cost ◽  
Digital Elevation Models ◽  
Point Clouds ◽  
Experimental Conditions ◽  
Weathered Rock ◽  
Topographic Data ◽  
Digital Elevation ◽  
Dense Point

Abstract. We have generated sub-millimetre-resolution DEMs of weathered rock surfaces using SfM photogrammetry techniques. We apply a close-range method based on structure-from-motion (SfM) photogrammetry in the field and use it to generate high-resolution topographic data for weathered boulders and bedrock. The method was pilot tested on extensively weathered Triassic Moenkopi sandstone outcrops near Meteor Crater in Arizona. Images were taken in the field using a consumer-grade DSLR camera and were processed in commercially available software to build dense point clouds. The point clouds were registered to a local 3-D coordinate system (x, y, z), which was developed using a specially designed triangle-coded control target and then exported as digital elevation models (DEMs). The accuracy of the DEMs was validated under controlled experimental conditions. A number of checkpoints were used to calculate errors. We also evaluated the effects of image and camera parameters on the accuracy of our DEMs. We report a horizontal error of 0.5 mm and vertical error of 0.3 mm in our experiments. Our approach provides a low-cost method for obtaining very high-resolution topographic data on weathered rock surfaces (area < 10 m2). The results from our case study confirm the efficacy of the method at this scale and show that the data acquisition equipment is sufficiently robust and portable. This is particularly important for field conditions in remote locations or steep terrain where portable and efficient methods are required.

Pre-landslide topographic reconstruction using a Digital Elevation Model from CaSSIS onboard the Trace Gas Orbiter.

2021 ◽  
Author(s):  
Anthony Guimpier ◽  
Susan Conway ◽  
Maurizio Pajola ◽  
Alice Lucchetti ◽  
Emanuele Simioni ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging System ◽  
Three Dimensional ◽  
Vertical Resolution ◽  
Topographic Data ◽  
Contour Lines ◽  
Digital Elevation ◽  
Landslide Event ◽  
Imaging Science ◽  
Topographic Reconstruction

&lt;p&gt;Landslides are common features on the surface of Mars. They have morphologies that resemble debris slides, mudflows [1], or giant rock avalanches [e.g., 2] on Earth. They can mobilise large quantities of material up to 10&lt;sup&gt;12&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt; and spread over areas of up to 10&lt;sup&gt;9&lt;/sup&gt; m&lt;sup&gt;2&lt;/sup&gt; [e.g., 3].&lt;/p&gt;&lt;p&gt;The topography before the landslide event occurred is required to both estimate the volume of mobilised material and quantify the distribution and thickness of the deposit. The mass distribution of the deposit can also be used to compare with 3D flow simulations of landslides [e.g. 1, 3]. However, on Mars there are no landslides that have known topographic data before the event occurred, hence we have to rely on topographic reconstruction.&lt;/p&gt;&lt;p&gt;This type of reconstruction, which we have already carried out using HiRISE (High Resolution Imaging Science Experiment) Digital Elevation Models (DEM) with 1-2 m vertical resolution [e.g., 1], has never been undertaken using DEMs with 4-5 m vertical resolution derived from CaSSIS (Colour and Stereo Surface Imaging System) stereo pairs [4]. CaSSIS uses a 180&amp;#176; camera rotation to capture stereo images of a given site in a single pass. DEMs are then generated using 3DPD (three Dimensional reconstruction of Planetary Data) software [5].&lt;/p&gt;&lt;p&gt;Our aim is to test whether a landslide reconstruction can be carried out with a CaSSIS DEM. For our purpose we use a 6&amp;#160;km long landslide in Baetis Chaos region, Mars.&lt;/p&gt;&lt;p&gt;Our reconstruction consists of three main steps: 1) We first calculate contour lines. 2) Reconstructed contour lines are then drawn by connecting contour lines on either side of the boundary taking into account the overall topography outside the landslide. 3) Then, the reconstructed contour lines are converted into points at intervals equal to the spatial resolution of the DEM. These points are then interpolated using a natural neighbour algorithm to calculate a new DEM without the landslide. We were able to estimate that the landslide in Baetis Chaos has a volume of 10&lt;sup&gt;8&lt;/sup&gt;&amp;#160;m&lt;sup&gt;3&lt;/sup&gt; and the deposit has a maximum thickness of 200&amp;#160;m using CaSSIS data.&lt;/p&gt;&lt;p&gt;Our successful reconstruction using a CaSSIS DEM increases the potential coverage of high-resolution stereo-topographic data beyond those already available with CTX and/or HiRISE. The resolution CaSSIS DEMs fills a gap in the topographic data currently available for studying landslides. Landslides &gt; 15&amp;#160;km long can be studied with MOLA or HRSC data, and landslides &lt; 5 km long can be studied using HiRISE data. Now, landslides and other landforms 5-15&amp;#160;km can be studied using CaSSIS data with equivalent quality to CTX stereo-topography.&lt;/p&gt;&lt;p&gt;Acknowledgement:&amp;#160;CaSSIS is a project of the University of Bern, with instrument hardware development supported by INAF/Astronomical Observatory of Padova&amp;#160;(ASI-INAF agreement n.2020-17-HH.0), and the Space Research Center (CBK) in Warsaw.&lt;/p&gt;&lt;p&gt;References: [1] A. Guimpier et al. (In review) &lt;em&gt;PSS&lt;/em&gt;. [2] G. Magnarini et al. (2019) &lt;em&gt;Nature Communications&lt;/em&gt;. [3] G.B. Crosta et al. (2018) &lt;em&gt;ESS&lt;/em&gt;, 5, 89&amp;#8211;119. [4] A. Lucas et al. (2014) &lt;em&gt;Nature Communications&lt;/em&gt;. [5] E. Simioni et al. (In press) &lt;em&gt;PSS&lt;/em&gt;.&lt;/p&gt;

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