scholarly journals The impact of sea state condition on airborne lidar bathymetry measurements

2012 ◽  
Author(s):  
Torbjorn Karlsson ◽  
Shachak Pe'eri ◽  
Andreas Axelsson
Keyword(s):  
Airborne Lidar ◽  
State Condition ◽  
Sea State ◽  
Airborne Lidar Bathymetry ◽  
The Impact

scholarly journals The Impact of Offshore Wind Farms on Sea State Demonstrated by Airborne LiDAR Measurements

2021 ◽  
Vol 9 (6) ◽  
pp. 644
Author(s):  
Konrad Bärfuss ◽  
Johannes Schulz-Stellenfleth ◽  
Astrid Lampert
Keyword(s):  
Spectral Energy Distribution ◽  
Laser Scanner ◽  
Wind Farms ◽  
Airborne Lidar ◽  
Offshore Wind ◽  
Spectral Energy ◽  
Sea State ◽  
Offshore Wind Farms ◽  
The North ◽  
The Impact

The increasing number of wind farms installed in the North Sea has an impact on the downstream wind speed. This has been hypothesized as well for sea state properties. Wave effects can be expected in particular in fetch-limited conditions with offshore wind directions. With systematic flights deploying an airborne laser scanner, these impacts are shown directly for the first time. The flights were conducted perpendicular to the main wind direction upstream and downstream of the cluster of the offshore wind parks Amrumbank West, Nordsee Ost, and Meerwind Süd/Ost. The flight legs covered the area potentially influenced by the wind parks and the undisturbed area next to the wind parks. The analysis of the spectral energy distribution shows a re-distribution of the wave energy in the downstream area with enhanced energy at smaller wavelengths. The effect is still clearly visible at a distance of 55 km. As the sea surface constitutes the link between the atmosphere and the ocean, it is very likely that wind parks modify the properties of the water column as well.

scholarly journals A MATLAB GEODETIC SOFTWARE FOR PROCESSING AIRBORNE LIDAR BATHYMETRY DATA

2015 ◽  
Vol XL-5/W5 ◽  
pp. 167-170 ◽  
Author(s):  
M. Pepe ◽  
G. Prezioso
Keyword(s):  
Laser Scanning ◽  
Point Clouds ◽  
Geoid Undulation ◽  
Airborne Lidar ◽  
Navigation Systems ◽  
Ellipsoidal Height ◽  
Geoid Model ◽  
Intelligence Agency ◽  
Airborne Lidar Bathymetry ◽  
The Impact

The ability to build three-dimensional models through technologies based on satellite navigation systems GNSS and the continuous development of new sensors, as Airborne Laser Scanning Hydrography (ALH), data acquisition methods and 3D multi-resolution representations, have contributed significantly to the digital 3D documentation, mapping, preservation and representation of landscapes and heritage as well as to the growth of research in this fields. <br><br> However, GNSS systems led to the use of the ellipsoidal height; to transform this height in orthometric is necessary to know a geoid undulation model. The latest and most accurate global geoid undulation model, available worldwide, is EGM2008 which has been publicly released by the U.S. National Geospatial-Intelligence Agency (NGA) EGM Development Team. Therefore, given the availability and accuracy of this geoid model, we can use it in geomatics applications that require the conversion of heights. Using this model, to correct the elevation of a point does not coincide with any node must interpolate elevation information of adjacent nodes. <br><br> The purpose of this paper is produce a Matlab® geodetic software for processing airborne LIDAR bathymetry data. In particular we want to focus on the point clouds in ASPRS LAS format and convert the ellipsoidal height in orthometric. The algorithm, valid on the whole globe and operative for all UTM zones, allows the conversion of ellipsoidal heights using the EGM2008 model. Of this model we analyse the slopes which occur, in some critical areas, between the nodes of the undulations grid; we will focus our attention on the marine areas verifying the impact that the slopes have in the calculation of the orthometric height and, consequently, in the accuracy of the in the 3-D point clouds. This experiment will be carried out by analysing a LAS APRS file containing topographic and bathymetric data collected with LIDAR systems along the coasts of Oregon and Washington (USA).

scholarly journals Refined Geometric Modeling of Laser Pulse Propagation in Airborne LiDAR Bathymetry

2021 ◽  
Author(s):  
Katja Richter ◽  
David Mader ◽  
Patrick Westfeld ◽  
Hans-Gerd Maas
Keyword(s):  
Geometric Modeling ◽  
Water Surface ◽  
Pulse Propagation ◽  
Geometric Model ◽  
Airborne Lidar ◽  
Surface Geometry ◽  
Accurate Representation ◽  
Airborne Lidar Bathymetry ◽  
The Impact ◽  
Water Bottom

AbstractTo achieve a geometrically accurate representation of the water bottom, airborne LiDAR bathymetry (ALB) requires the correction of the raw 3D point coordinates due to refraction at the air–water interface, different signal velocity in air and water, and further propagation induced effects. The processing of bathymetric LiDAR data is based on a geometric model of the laser bathymetry pulse propagation describing the complex interactions of laser radiation with the water medium and the water bottom. The model comprises the geometric description of laser ray, water surface, refraction, scattering in the water column, and diffuse bottom reflection. Conventional geometric modeling approaches introduce certain simplifications concerning the water surface, the laser ray, and the bottom reflection. Usually, the local curvature of the water surface and the beam divergence are neglected and the travel path of the outgoing and the returned pulse is assumed to be identical. The deviations between the applied geometric model and the actual laser beam path cause a coordinate offset at the water bottom, which affects the accuracy potential of the measuring method. The paper presents enhanced approaches to geometric modeling which are based on a more accurate representation of water surface geometry and laser ray geometry and take into account the diffuse reflection at the water bottom. The refined geometric modeling results in an improved coordinate accuracy at the water bottom. The impact of the geometric modeling methods on the accuracy of the water bottom points is analyzed in a controlled manner using a laser bathymetry simulator. The findings will contribute to increase the accuracy potential of modern ALB systems.

AIRBORNE LIDAR BATHYMETRY ON RUMOI COAST IN HOKKAIDO

2019 ◽  
Vol 75 (2) ◽  
pp. I_115-I_120
Author(s):  
Shinji IKI ◽  
Tatsuo FUJIYAMA ◽  
Kiwamu KADOWAKI ◽  
Tomoaki YOKOTA ◽  
Tomoharu WATANABE ◽  
...  
Keyword(s):  
Airborne Lidar ◽  
Airborne Lidar Bathymetry

Registration of Airborne LiDAR Bathymetry and Multibeam Echo Sounder Point Clouds

2021 ◽  
pp. 1-5
Author(s):  
Xiankun Wang ◽  
Fanlin Yang ◽  
Hande Zhang ◽  
Dianpeng Su ◽  
Zhiliang Wang ◽  
...  
Keyword(s):  
Point Clouds ◽  
Airborne Lidar ◽  
Airborne Lidar Bathymetry ◽  
Echo Sounder

scholarly journals PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 261-266
Author(s):  
A.-L. Montreuil ◽  
M. Chen ◽  
A. Esquerré ◽  
R. Houthuys ◽  
R. Moelans ◽  
...  
Keyword(s):  
Management Practices ◽  
Morphological Changes ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Airborne Lidar ◽  
Coastline Change ◽  
The Mean ◽  
The Impact

<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>

Waveform decomposition and feature extraction of airborne LiDAR bathymetry

2021 ◽  
Author(s):  
Liu Jiaoyang ◽  
Su Dianpeng ◽  
Qi Chao ◽  
Yang Anxiu ◽  
Wang Xiankun ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Airborne Lidar ◽  
Airborne Lidar Bathymetry

Impact of the Uncertainties of the RAOs of a Semisubmersible Platform on the Performance of a Motion-Based Wave Inference Method

2019 ◽  
Author(s):  
J. Mas-Soler ◽  
Pedro C. de Mello ◽  
Eduardo A. Tannuri ◽  
Alexandre N. Simos ◽  
A. Souto-Iglesias
Keyword(s):  
Bayesian Inference ◽  
Transfer Functions ◽  
Inference Model ◽  
Sea State ◽  
Statistical Errors ◽  
Regularization Parameters ◽  
Ill Posed ◽  
State Estimations ◽  
The Impact ◽  
Mathematical Process

Abstract Motion based wave inference allows the estimation of the directional sea spectrum from the measured motions of a vessel. Solving the resulting inverse problem is challenging as it is often ill-posed; as a matter of fact, statistical errors of the estimated platform response functions (RAOs) may lead to misleading estimations of the sea states as many noise values are severely amplified in the mathematical process. Hence, in order to obtain reliable estimations of the sea conditions some hypothesis must be included by means of regularization parameters. This work discusses how these errors affect the regularization parameters and the accuracy of the sea state estimations. For this purpose, a statistical quantification of the errors associated to the estimated transfer functions has been included in an expanded Bayesian inference approach. Then, the resulting statistical inference model has been verified by means of a comparison between the outputs of this approach and those obtained without considering the statistical errors in the Bayesian inference. The assessment of the impact on the accuracy of the estimations is based on the results of a dedicated model-scale experimental campaign, which includes more than 150 different test conditions.

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