scholarly journals Self-AdaptIve LOcal Relief Enhancer (SAILORE): A New Filter to Improve Local Relief Model Performances According to Local Topography

Geomatics ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 450-463
Author(s):  
Jean-Pierre TOUMAZET ◽  
François-Xavier SIMON ◽  
Alfredo MAYORAL
Keyword(s):  
Low Frequency ◽  
View Factor ◽  
Digital Elevation ◽  
Local Relief ◽  
Optimal Values ◽  
Elevation Model ◽  
Filtering Effect ◽  
Steep Slopes ◽  
Natural Slopes ◽  
Self Adaptive

The use of Light Detection and Ranging (LiDAR) is becoming more and more common in different landscape exploration domains such as archaeology or geomorphology. In order to allow the detection of features of interest, visualization filters have to be applied to the raw Digital Elevation Model (DEM), to enhance small relief variations. Several filters have been proposed for this purpose, such as Sky View Factor, Slope, negative and positive Openness, or Local Relief Model (LRM). The efficiency of each of these methods is strongly dependent on the input parameters chosen in regard of the topography of the investigated area. The LRM has proved to be one of the most efficient, but it has to be parameterized in order to be adapted to the natural slopes characterizing the investigated area. Generally, this setting has a single value, chosen as the best compromise between optimal values for each relief configuration. As LiDAR is mainly used in wide areas, a large distribution of natural slopes is often encountered. The aim of this paper is to propose a Self AdaptIve LOcal Relief Enhancer (SAILORE) based on the Local Relief Model approach. The filtering effect is adapted to the local slope, allowing the detection at the same time of low-frequency relief variation on flat areas, as well as the identification of high-frequency relief variation in the presence of steep slopes. First, the interest of this self-adaptive approach is presented, and the principle of the method, compared to the classical LRM method, is described. This new tool is then applied to a LiDAR dataset characterized by various terrain configurations in order to test its performance and compare it with the classical LRM. The results of this test show that SAILORE significantly increases the detection capability while simplifying it.

scholarly journals Strengths of Exaggerated Tsunami-Originated Placenames: Disaster Subculture in Sanriku Coast, Japan

2019 ◽  
Vol 8 (10) ◽  
pp. 429 ◽  
Author(s):  
Yuzuru Isoda ◽  
Akio Muranaka ◽  
Go Tanibata ◽  
Kazumasa Hanaoka ◽  
Junzo Ohmura ◽  
...  
Keyword(s):  
Low Frequency ◽  
Local Area ◽  
Local Communities ◽  
Sanriku Coast ◽  
The Past ◽  
Disaster Experience ◽  
Digital Elevation ◽  
Disaster Subculture ◽  
Group Interviews ◽  
Elevation Model

Disaster-originated placename is a kind of disaster subculture that is used for a practical purpose of identifying a location while reminding the past disaster experience. They are expected to transmit the risks and knowledge of high-risk low-frequency natural hazards, surviving over time and generations. This paper compares the perceptions to tsunami-originated placenames in local communities having realistic and exaggerated origins in Sanriku Coast, Japan. The reality of tsunami-originated placenames is first assessed by comparing the tsunami run-ups indicated in the origins and that of the tsunami in the Great East Japan Earthquake 2011 using GIS and digital elevation model. Considerable proportions of placenames had exaggerated origins, but the group interviews to local communities revealed that origins indicating unrealistic tsunami run-ups were more believed than that of the more realistic ones. We discuss that accurate hazard information will be discredited if it contradicts to the people’s everyday life and the desire for safety, and even imprecise and ambiguous information can survive if it is embedded to a system of local knowledge that consistently explains the various facts in a local area that requires explanation.

scholarly journals ACCURACY OF 3D RECONSTRUCTION IN AN ILLUMINATION DOME

2016 ◽  
Vol XLI-B5 ◽  
pp. 69-76 ◽  
Author(s):  
Lindsay MacDonald ◽  
Isabella Toschi ◽  
Erica Nocerino ◽  
Mona Hess ◽  
Fabio Remondino ◽  
...  
Keyword(s):  
Surface Reconstruction ◽  
High Frequency ◽  
Point Cloud ◽  
Laser Scanner ◽  
Low Frequency ◽  
Photometric Stereo ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Digital Elevation ◽  
Elevation Model

The accuracy of 3D surface reconstruction was compared from image sets of a Metric Test Object taken in an illumination dome by two methods: photometric stereo and improved structure-from-motion (SfM), using point cloud data from a 3D colour laser scanner as the reference. Metrics included pointwise height differences over the digital elevation model (DEM), and 3D Euclidean differences between corresponding points. The enhancement of spatial detail was investigated by blending high frequency detail from photometric normals, after a Poisson surface reconstruction, with low frequency detail from a DEM derived from SfM.

scholarly journals ACCURACY OF 3D RECONSTRUCTION IN AN ILLUMINATION DOME

2016 ◽  
Vol XLI-B5 ◽  
pp. 69-76
Author(s):  
Lindsay MacDonald ◽  
Isabella Toschi ◽  
Erica Nocerino ◽  
Mona Hess ◽  
Fabio Remondino ◽  
...  
Keyword(s):  
Surface Reconstruction ◽  
High Frequency ◽  
Point Cloud ◽  
Laser Scanner ◽  
Low Frequency ◽  
Photometric Stereo ◽  
Point Cloud Data ◽  
Cloud Data ◽  
Digital Elevation ◽  
Elevation Model

The accuracy of 3D surface reconstruction was compared from image sets of a Metric Test Object taken in an illumination dome by two methods: photometric stereo and improved structure-from-motion (SfM), using point cloud data from a 3D colour laser scanner as the reference. Metrics included pointwise height differences over the digital elevation model (DEM), and 3D Euclidean differences between corresponding points. The enhancement of spatial detail was investigated by blending high frequency detail from photometric normals, after a Poisson surface reconstruction, with low frequency detail from a DEM derived from SfM.

scholarly journals Monitoring Errors of Semi-Mechanized Coffee Planting by Remotely Piloted Aircraft

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1224
Author(s):  
Lucas Santos Santana ◽  
Gabriel Araújo e Silva Ferraz ◽  
João Paulo Barreto Cunha ◽  
Mozarte Santos Santana ◽  
Rafael de Oliveira Faria ◽  
...  
Keyword(s):  
Process Control ◽  
Statistical Process Control ◽  
Aerial Images ◽  
Statistical Process ◽  
Digital Elevation ◽  
Dependent Variables ◽  
Remotely Piloted Aircraft ◽  
Elevation Model ◽  
Steep Slopes

Mechanized operations on terrain slopes can still lead to considerable errors in the alignment and distribution of plants. Knowing slope interference in semi-mechanized planting quality can contribute to precision improvement in decision making, mainly in regions with high slope. This study evaluates the quality of semi-mechanized coffee planting in different land slopes using a remotely piloted aircraft (RPA) and statistical process control (SPC). In a commercial coffee plantation, aerial images were collected by a remotely piloted aircraft (RPA) and subsequently transformed into a digital elevation model (DEM) and a slope map. Slope data were subjected to variance analysis and statistical process control (SPC). Dependent variables analyzed were variations in distance between planting lines and between plants in line. The distribution of plants on all the slopes evaluated was below expected; the most impacted was the slope between 20–25%, implementing 7.8% fewer plants than projected. Inferences about the spacing between plants in the planting row showed that in slopes between 30–40%, the spacing was 0.53 m and between 0 and 15% was 0.55 m. This denotes the compensation of the speed of the operation on different slopes. The spacing between the planting lines had unusual variations on steep slopes. The SCP quality graphics are of lower quality in operations between 30–40%, as they have an average spacing of 3.65 m and discrepant points in the graphics. Spacing variations were observed in all slopes as shown in the SCP charts, and possible causes and implications for future management were discussed, contributing to improvements in the culture installation stage.

scholarly journals DISTRIBUTION AND EVOLUTION OF ICE APRONS IN A CHANGING CLIMATE IN THE MONT-BLANC MASSIF (WESTERN EUROPEAN ALPS)

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 469-475
Author(s):  
S. Kaushik ◽  
L. Ravanel ◽  
F. Magnin ◽  
Y. Yan ◽  
E. Trouve ◽  
...  
Keyword(s):  
Slope Aspect ◽  
European Alps ◽  
Equilibrium Line Altitude ◽  
Mountain Areas ◽  
Area Loss ◽  
Digital Elevation ◽  
Elevation Model ◽  
Optical Satellite Images ◽  
Steep Slopes ◽  
Mont Blanc Massif

Abstract. Ice Apron (IA) is a poorly studied ice feature, commonly existing in all the world’s major mountain regions. This study aims to map the locations of the IAs in the Mont Blanc massif (MBM), making use of the very high-resolution optical satellite images from 2001, 2012 and 2019. 423 IAs were identified and accurately delineated in the MBM on the images from 2019, and their topographic characteristics were studied. We generated our own Digital Elevation Model (DEM) at 4 m resolution since the freely available products predominantly suffer from significant inconsistencies, especially in steep mountain areas. Results show that most IAs exist at elevations above the regional Equilibrium Line Altitude (ELA), on steep slopes, on concave surfaces, on northern and southern aspects and on the most rugged terrains. They are also commonly associated with steep slope glaciers as 85% of them occur on these glaciers’ headwalls. A comparison between 2001 and 2019 shows that IAs have lost around 29% of their area over a period of 18 years. This is significant and the rate of area loss is very alarming in comparison with the larger glacier bodies. We also studied the effect of topographic parameters on the area loss. We found that topographic factors like slope, aspect, curvature, elevation and Terrain Ruggedness Index (TRI) strongly influence the rate of area loss of IAs.

Enhancing subtle seafloor relief variation: relief visualisation techniques for bathymetric data 

2021 ◽  
Author(s):  
Ana Novak ◽  
Sašo Poglajen ◽  
Marko Vrabec
Keyword(s):  
Small Scale ◽  
View Factor ◽  
M Cell ◽  
Northern Adriatic ◽  
Bathymetric Data ◽  
Continental Shelves ◽  
Digital Elevation ◽  
Local Relief ◽  
Oriented Parallel ◽  
Local Dominance

<p>Bathymetric data is commonly visualized as a simple shaded relief, where features oriented parallel to the light source are prone to false topographic perception or are even obscured to the viewer. On the other hand, many relief visualisation techniques developed in past decades are extensively used in visualisation and analysis of high-resolution digital elevation models, especially in geomorphological and archaeological studies. We tested and assessed the suitability of relief visualisation techniques provided by the Relief Visualisation Toolbox (RVT) software for representation of bathymetric data. We used a multibeam-sonar derived bathymetric model with a 10 x 10 m cell size from the Gulf of Trieste (northern Adriatic) characterised by a shallow low-relief seabed. Our results clearly demonstrate the effectiveness of relief visualisation techniques for exposing subtle relief variation in bathymetric data. We find that small-scale features (outcrops, wrecks, pockmarks, reefs, etc.) and negative linear features are best highlighted by “visualization for archaeological topography” (VAT) and “openness” techniques. High-relief features and topographic infection points are pronounced by “hillshade from multiple directions” and “sky-view factor” (SVF). Finally, “principal components analysis” (PCA), “prismatic openness”, “simple local relief model”, “anisotropic SVF” and “local dominance” algorithms show best results when we want to highlight both high- and low-relief features in one image. The tested techniques are far superior to a simple hillshade visualisation especially when imaging low-gradient relief (common on continental shelves and abyssal plains) where topographic details are often not adequately pronounced by hillshading. To our knowledge, this study represents the first attempt to test and compare several relief visualisation techniques for bathymetric data.  </p>

scholarly journals Assessment of debris-flow susceptibility at medium-scale in the Barcelonnette Basin, France

2011 ◽  
Vol 11 (2) ◽  
pp. 627-641 ◽  
Author(s):  
M. S. Kappes ◽  
J.-P. Malet ◽  
A. Remaître ◽  
P. Horton ◽  
M. Jaboyedoff ◽  
...  
Keyword(s):  
Regional Scale ◽  
Low Frequency ◽  
Data Availability ◽  
Limiting Factor ◽  
Case Scenario ◽  
Worst Case ◽  
High Dependency ◽  
Digital Elevation ◽  
Elevation Model

Abstract. Debris flows are among the most dangerous processes in mountainous areas due to their rapid rate of movement and long runout zone. Sudden and rather unexpected impacts produce not only damages to buildings and infrastructure but also threaten human lives. Medium- to regional-scale susceptibility analyses allow the identification of the most endangered areas and suggest where further detailed studies have to be carried out. Since data availability for larger regions is mostly the key limiting factor, empirical models with low data requirements are suitable for first overviews. In this study a susceptibility analysis was carried out for the Barcelonnette Basin, situated in the southern French Alps. By means of a methodology based on empirical rules for source identification and the empirical angle of reach concept for the 2-D runout computation, a worst-case scenario was first modelled. In a second step, scenarios for high, medium and low frequency events were developed. A comparison with the footprints of a few mapped events indicates reasonable results but suggests a high dependency on the quality of the digital elevation model. This fact emphasises the need for a careful interpretation of the results while remaining conscious of the inherent assumptions of the model used and quality of the input data.

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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