RISK LEVEL ASSESSMENT OF SMALL-SCALE MOUNTAINS STREAM USING A DIGITAL ELEVATION MODEL

2021 ◽  
Vol 77 (1) ◽  
pp. 24-38
Author(s):  
Taiki MORI ◽  
Tomoyasu SUGIYAMA ◽  
Yoshifumi SATOFUKA ◽  
Hiroshi TOCHINO
Keyword(s):  
Digital Elevation Model ◽  
Risk Level ◽  
Small Scale ◽  
Digital Elevation ◽  
Elevation Model

scholarly journals First Evaluation of Topography on GNSS-R: An Empirical Study Based on a Digital Elevation Model

2019 ◽  
Vol 11 (21) ◽  
pp. 2556 ◽  
Author(s):  
Hugo Carreno-Luengo ◽  
Guido Luzi ◽  
Michele Crosetto
Keyword(s):  
Soil Moisture ◽  
Digital Elevation Model ◽  
Small Scale ◽  
Navigation Satellite ◽  
Topographic Wetness Index ◽  
Digital Elevation ◽  
Global Navigation ◽  
Elevation Model ◽  
Global Navigation Satellite ◽  
Topographic Parameters

Understanding the effects of Earth’s surface topography on Global Navigation Satellite Systems Reflectometry (GNSS-R) space-borne data is important to calibrate experimental measurements, so as to provide accurate soil moisture content (SMC) retrievals. In this study, several scientific observables obtained from delay-Doppler maps (DDMs) ⟨ | Y r , t o p o ( τ , f ) | 2 ⟩ generated on board the Cyclone Global Navigation Satellite System (CyGNSS) mission were evaluated as a function of several topographic parameters derived from a digital elevation model (DEM). This assessment was performed as a function of Soil Moisture Active Passive (SMAP)-derived SMC at grazing angles θ e ~ [20,30] ° and in a nadir-looking configuration θ e ~ [80,90] °. Global scale results showed that the width of the trailing edge (TE) was small T E ~ [100, 250] m and the reflectivity was high Γ ~ [–10, –3] dB over flat areas with low topographic heterogeneity, because of an increasing coherence of Earth-reflected Global Positioning System (GPS) signals. However, the strong impact of several topographic features over areas with rough topography provided motivation to perform a parametric analysis. A specific target area with little vegetation, low small-scale surface roughness, and a wide variety of terrains in South Asia was selected. A significant influence of several topographic parameters i.e., surface slopes and curvatures was observed. This triggered our study of the sensitivity of T E and Γ to SMC and topographic wetness index ( T W I ). Regional scale results showed that T E and Γ are strongly correlated with the T W I , while the sensitivity to SMC was almost negligible. The Pearson correlation coefficients of T E and Γ with T W I are r Γ ~ 0.59 and r T E ~−0.63 at θ e ~ [20, 30] ° and r Γ ~ 0.48 and r T E ~ −0.50 at θ e ~ [80, 90] °, respectively.

scholarly journals DIGITAL ELEVATION MODEL TO VISUALIZE SMALL SPATIAL OBJECT IN 3D

MATICS ◽  
2012 ◽  
Author(s):  
Cahyo Crysdian
Keyword(s):  
Digital Elevation Model ◽  
3D Visualization ◽  
Small Scale ◽  
Data Set ◽  
Spatial Object ◽  
Population Average ◽  
Digital Elevation ◽  
Elevation Data ◽  
Elevation Model ◽  
Srtm Data

<div class="Section1"><p><strong> </strong>An effort to develop a Digital Elevation Model (DEM) for small scale spatial objects is presented in this paper. The motivation of the research is to visualize a small spatial object as detail as possible in 3D, thus the presentation of the object in term of a computer model is similar to its presentation in reality. To reach this objective, the research was conducted in four stages i.e. elevation data retrieval, 3D visualization and its enhancement, and the development of blank data removal. Elevation data is obtained from SRTM dataset that has 3 arc-second or approximately 90 meters data resolution. Data obtained from SRTM is then visualized in 3D, in which visualization is enriched with view angle setting. Results of visualization show that enhancement to SRTM data set is required to present elevation data in 3D. It is due to the existence of blank data contained in the elevation data retrieved from SRTM. Therefore, this paper proposes two methods to enhance SRTM dataset i.e. population average and neighbors average, in order to counter the existence of blank data. The first method uses the population average of statistic to eliminate blank data, while the latter relies on the average value of its neighboring pixels. Comparison among those methods is held in this research to disclose the performance of each method. Result of comparison shows that the method based on neighbors average outperform population average method to eliminate blank data contained in SRTM data set. Thus, neighbor average delivers better 3D visualization for small scale spatial object.</p></div><em> </em> <p><em> </em></p> <p><strong>Keywords:</strong> Digital Elevation Model, 3D Visualization, Spatial</p>

HYPSO: a new multiresolution global raster digital elevation model for small-scale terrain mapping

2021 ◽  
Author(s):  
Timofey Samsonov
Keyword(s):  
Digital Elevation Model ◽  
Digital Elevation Models ◽  
Small Scale ◽  
Russian Science ◽  
Levels Of Detail ◽  
Digital Elevation ◽  
Elevation Data ◽  
Data Source ◽  
Elevation Model ◽  
Terrain Features

&lt;p&gt;During the last decade a significant progress in methods and techniques of elevation data acquisition has been achieved. With lidar-derived digital elevation models it is now possible to investigate landforms with precision and detail which was never possible before. The resolution of global and continental elevation models is approaching first meters, which enables detailed geomorphometric analysis and mapping in wide spatial extents. At the same time, Earth scientists are interested not only in learning the properties of small landforms, but also in investigating the large regional terrain features, as well as hierarchical properties of terrain structure. For this, small details must be omitted from digital elevation model, and the analyzed dataset is expected to have coarser resolution. Currently available coarse-resolution global digital elevation models such as GMTED2010, GEBCO_2019 and ETOPO1 are characterized by spatial resolution ranging from 7.5&amp;#8221; to 1&amp;#8217;, which is approximately equal to cell size of 250-2000 m on the equator. Such resolution fits well into the small-scale mapping and analysis context. However, these models have excessive level of detail in relation to their resolution, which is a consequence of the method of their derivation &amp;#8212; mainly aggregation and resampling of more detailed data. As a result, terrain maps created using these models, are characterized by lack of generalization, which prevents realistic portray of large terrain forms. To solve the problem, the new high-quality mutiresolution digital elevation model HYPSO has been developed. HYPSO is derived based on GEBCO_2019 model (15&amp;#8221; resolution) using the structural generalization, during which the less detailed terrain surface is reconstructed from characteristic stream and watershed lines. HYPSO includes eight levels of detail (LoDs) with resolutions 30&amp;#8221;, 1&amp;#8217;, 2&amp;#8217;, 4&amp;#8217;, 8&amp;#8217;, 16&amp;#8217;, 32&amp;#8217; and 64&amp;#8217; which are suitable for mapping any region on the Earth including the seabed at scales 1:1 000&amp;#160;000 and smaller. The sequence of LoDs is characterized by sequential decrease in detail, which enables production of multiscale maps. Additionally, HYPSO is spatially conflated with river/lake centerlines in popular Natural Earth cartographic database and can be used as a background terrain layer in production of general geographic (base) maps. While the primary purpose of HYPSO is hypsometric mapping, it is also suitable as a data source for performing the geomorphometric analysis aimed at investigating the properties of large terrain landforms, which is demonstrated on several examples.&lt;/p&gt;&lt;p&gt;&lt;em&gt;The study was supported by the Russian Science Foundation grant No. 19-77-10071&lt;/em&gt;&lt;/p&gt;

STUDY OF THE LANDSLIDE MORPHOLOGY BASED ON GNSS DATA AND AIRBORNE SOUNDING (ON THE EXAMPLE OF A SECTION OF THE PROTVA RIVER VALLEY)

2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Geodetic Network ◽  
Aerial Survey ◽  
River Valley ◽  
Ease Of Use ◽  
Digital Elevation ◽  
Loose Deposits ◽  
Positioning Method ◽  
Landslide Body ◽  
Elevation Model

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.

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