scholarly journals The importance of atmospheric correction for airborne hyperspectral remote sensing of shallow waters: application to depth estimation

2017 ◽  
Vol 10 (10) ◽  
pp. 3919-3929 ◽  
Author(s):  
Elena Castillo-López ◽  
Jose Antonio Dominguez ◽  
Raúl Pereda ◽  
Julio Manuel de Luis ◽  
Ruben Pérez ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Accurate Determination ◽  
Atmospheric Correction ◽  
Principal Component ◽  
Depth Estimation ◽  
Correction Method ◽  
Shallow Waters ◽  
Depth Information ◽  
Cross Track

Abstract. Accurate determination of water depth is indispensable in multiple aspects of civil engineering (dock construction, dikes, submarines outfalls, trench control, etc.). To determine the type of atmospheric correction most appropriate for the depth estimation, different accuracies are required. Accuracy in bathymetric information is highly dependent on the atmospheric correction made to the imagery. The reduction of effects such as glint and cross-track illumination in homogeneous shallow-water areas improves the results of the depth estimations. The aim of this work is to assess the best atmospheric correction method for the estimation of depth in shallow waters, considering that reflectance values cannot be greater than 1.5 % because otherwise the background would not be seen. This paper addresses the use of hyperspectral imagery to quantitative bathymetric mapping and explores one of the most common problems when attempting to extract depth information in conditions of variable water types and bottom reflectances. The current work assesses the accuracy of some classical bathymetric algorithms (Polcyn–Lyzenga, Philpot, Benny–Dawson, Hamilton, principal component analysis) when four different atmospheric correction methods are applied and water depth is derived. No atmospheric correction is valid for all type of coastal waters, but in heterogeneous shallow water the model of atmospheric correction 6S offers good results.

scholarly journals The importance of Atmospheric Correction for Airborne Hyperspectral Remote Sensing of Shallow Waters. Application to Depth Estimation

2017 ◽  
Author(s):  
Elena Castillo-López ◽  
Jose Antonio Dominguez ◽  
Raúl Pereda ◽  
Julio Manuel de Luis ◽  
Ruben Pérez ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Accurate Determination ◽  
Atmospheric Correction ◽  
Principal Component ◽  
Depth Estimation ◽  
Correction Method ◽  
Shallow Waters ◽  
Depth Information ◽  
Cross Track

Abstract. Abstract. Accurate determination of water depth is indispensable in multiple aspects of civil engineering (dock construction, dikes, submarines outfalls, trench control, etc.). According to the final objective, different accuracies will be required. Accuracy in bathymetric information is highly dependent on the atmospheric correction made to the imagery. The reduction of effects such as glint and cross track illumination in shallow-water areas with homogeneous improves the results of the depth estimations. The aim of this work is to assess the best atmospheric correction method for the estimation of depth in shallow waters. This paper addresses the use of hyperspectral imagery to quantitative bathymetric mapping, and explores one of the most common problems when attempting to extract depth information in conditions of variable water types and bottom reflectances. The current work assesses the accuracy of some classical bathymetric algorithms (Polcyn-Lyzenga, Philpot, Benny-Dawson, Hamilton, Principal Component Analysis) when four different atmospheric correction methods are applied and water depth is derived. This work shows the importance of atmospheric correction in order to depth estimation in shallow waters. None atmospheric correction is valid for all type of coastal waters but in heterogeneous shallow water, the model of atmospheric correction 6S offers good results.

scholarly journals Accurate Refraction Correction—Assisted Bathymetric Inversion Using ICESat-2 and Multispectral Data

2021 ◽  
Vol 13 (21) ◽  
pp. 4355
Author(s):  
Changda Liu ◽  
Jiawei Qi ◽  
Jie Li ◽  
Qiuhua Tang ◽  
Wenxue Xu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Incidence Angle ◽  
Correction Method ◽  
Emission Angle ◽  
Sea Surface ◽  
Depth Information ◽  
Multispectral Data ◽  
Position Correction ◽  
Shallow Water Depth

Shallow-water depth information is essential for ship navigation and fishery farming. However, the accurate acquisition of shallow-water depth has been a challenge for marine mapping. Combining Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) bathymetry data with multispectral data, satellite-derived bathymetry is a promising solution through which to obtain bathymetric information quickly and accurately. This study proposes a photon refraction correction method considering sea-surface undulations to address errors in the underwater photons obtained by the ICESat-2. First, the instantaneous sea surface and beam emission angle are integrated to determine the sea-surface incidence angle. Next, the distance of photon propagation in water is determined using sea-surface undulation and Snell’s law. Finally, position correction is performed through geometric relationships. The corrected photons were combined with the multispectral data for bathymetric inversion, and a bathymetric map of the Yongle Atoll area was obtained. A bathymetric chart was created using the corrected photons and the multispectral data in the Yongle Atoll. Comparing the results of different refraction correction methods with the data measured shows that the refraction correction method proposed in this paper can effectively correct bathymetry errors: the root mean square error is 1.48 m and the R2 is 0.86.

Estimation of Shallow Water Depth Using HJ-1C S-band SAR Data

2015 ◽  
Vol 69 (1) ◽  
pp. 113-126 ◽  
Author(s):  
Xiaolin Bian ◽  
Yun Shao ◽  
Wei Tian ◽  
Chunyan Zhang
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Depth Estimation ◽  
Absolute Error ◽  
Fast Fourier Transformation ◽  
Linear Dispersion ◽  
Initial Water ◽  
Sar Data ◽  
Shallow Water Depth ◽  
Water Depths

This paper presents a shallow water depth estimation methodology using S-band Synthetic Aperture Radar (SAR) data from the HJ-1C satellite. It is based on the shoaling and refraction of long surface gravity waves as they propagate shoreward. A two-scale Bragg scattering model is used to describe the imaging process of long waves by SAR. By computing the Fast Fourier Transformation (FFT) for the selected sub image, wavelength and direction of the long wave can be retrieved from the two-dimensional (2D) spectra with wave tracking technology. Shallow water depths are then obtained from the linear dispersion relation with the calculated angular wave frequency obtained from other sources or first guesses of initial water depths or wave periods. Applicability and effectiveness are tested in the near-shore area of the Fujian province, China. Comparison between the derived results and water depths from an Electronic Navigational Chart (ENC) indicates that HJ-1C SAR is capable of higher resolution underwater topography detection, and the methodology can be used for shallow water depth estimation with good accuracy. The average absolute error and average relative error of the estimated results is 0·86 m and 11·05%, respectively.

New Approach for Assessment of Flexible Risers Interference in Shallow Waters

2013 ◽  
Author(s):  
Elton J. B. Ribeiro ◽  
Edson L. Labanca ◽  
Roberto Alvim ◽  
Otavio Veras
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Critical Issue ◽  
Shallow Waters ◽  
Wake Effect ◽  
Hydrodynamic Coefficient ◽  
New Approach ◽  
Campos Basin ◽  
Internal Fluid ◽  
Flexible Risers

This paper presents a methodology to analyze the risers interference connected to an FPSO, which is using turret moored system in shallow water. It is not feasible in shallow water to use riser free hanging catenary configurations, since there is not enough length in order to dissipate FPSO dynamic response due to wave action, which can cause riser damage at TDP. Furthermore, FPSO static offset is very large, around 30% of water depth, when it is compared with deep water, around 11–12% of water depth. In order to become feasible a large number of risers connected to a FPSO using a turret moored system in shallow water are needed to use compliant configurations, such as: lazy wave, pliant wave and Lazy S. As mentioned above risers compliant configurations are capable to avoid riser damage at TDP, but they present a large lateral motion. Thus, riser interference becomes a critical issue to be overcome. As the applicable standards and rules are not entirely prescriptive about this issue, the riser analyst usually have to adopt independent criteria, such as load cases, internal fluid density, hydrodynamic coefficient considering or not wake effect and clashing criteria (allowable, partially allowable or not). Therefore, the proposed methodology is very robust and was used at FEED studies for FPSO OSX-2/3, both belong to OGX, which are planning to install them at the ending of 2013 in Campos Basin, offshore Brazil.

scholarly journals Analysis of Very High Spatial Resolution Images for Automatic Shoreline Extraction and Satellite-Derived Bathymetry Mapping

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 172
Author(s):  
Giovanni Randazzo ◽  
Giovanni Barreca ◽  
Maria Cascio ◽  
Antonio Crupi ◽  
Marco Fontana ◽  
...  
Keyword(s):  
Shallow Water ◽  
Spatial Resolution ◽  
Water Depth ◽  
High Spatial Resolution ◽  
Satellite Image ◽  
Atmospheric Correction ◽  
Coastal Areas ◽  
Ratio Method ◽  
Very High Spatial Resolution ◽  
Very High

The amount of Earth observation images available to the public has been the main source of information, helping governments and decision-makers tackling the current world’s most pressing global challenge. However, a number of highly skilled and qualified personnel are still needed to fill the gap and help turn these data into intelligence. In addition, the accuracy of this intelligence relies on the quality of these images in times of temporal, spatial, and spectral resolution. For the purpose of contributing to the global effort aiming at monitoring natural and anthropic processes affecting coastal areas, we proposed a framework for image processing to extract the shoreline and the shallow water depth on GeoEye-1 satellite image and orthomosaic image acquired by an unmanned aerial vehicle (UAV) on the coast of San Vito Lo Capo, with image preprocessing steps involving orthorectification, atmospheric correction, pan sharpening, and binary imaging for water and non-water pixels analysis. Binary imaging analysis step was followed by automatic instantaneous shoreline extraction on a digital image and satellite-derived bathymetry (SDB) mapping on GeoEye-1 water pixels. The extraction of instantaneous shoreline was conducted automatically in ENVI software using a raster to vector (R2V) algorithm, whereas the SDB was computed in ArcGIS software using a log-band ratio method applied on the satellite image and available field data for calibration and vertical referencing. The results obtained from these very high spatial resolution images demonstrated the ability of remote sensing techniques in providing information where techniques using traditional methods present some limitations, especially due to their inability to map hard-to-reach areas and very dynamic near shoreline waters. We noticed that for the period of 5 years, the shoreline of San Vito Lo Capo sand beach migrated about 15 m inland, indicating the high dynamism of this coastal area. The bathymetric information obtained on the GeoEye-1 satellite image provided water depth until 10 m deep with R2 = 0.753. In this paper, we presented cost-effective and practical methods for automatic shoreline extraction and bathymetric mapping of shallow water, which can be adopted for the management and the monitoring of coastal areas.

scholarly journals Optical Model for Sea Grass Mapping and Water Depth Estimation in Shallow Water

2007 ◽  
Vol 54 ◽  
pp. 1451-1455
Author(s):  
Nobuhito MORI ◽  
Junichi NINOMIYA ◽  
Mamoru ARITA ◽  
Ichiro DEGUCHI ◽  
Toshiharu YOSHIDA ◽  
...  
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Optical Model ◽  
Depth Estimation ◽  
Sea Grass

scholarly journals IN-SITU MEASUREMENT OF DIFFUSE ATTENUATION COEFFICIENT AND ITS RELATIONSHIP WITH WATER CONSTITUENT AND DEPTH ESTIMATION OF SHALLOW WATERS BY REMOTE SENSING TECHNIQUE

2017 ◽  
Vol 14 (1) ◽  
pp. 47
Author(s):  
Budhi Agung Prasetyo ◽  
Vincentius Paulus Siregar ◽  
Syamsul Bahri Agus ◽  
Wikanti Asriningrum
Keyword(s):  
Attenuation Coefficient ◽  
Water Depth ◽  
Depth Estimation ◽  
In Situ Measurement ◽  
Shallow Waters ◽  
Landsat 8 ◽  
Band Ratio ◽  
Diffuse Attenuation Coefficient ◽  
The Relationship

Diffuse attenuation coefficient, Kd(λ), has an empirical relationship with water depth, thus potentially to be used to estimate the depth of the water based on the light penetration in the water column. The aim of this research is to assess the relationship of diffuse attenuation coefficient with the water constituent and its relationship to estimate the depth of shallow waters of Air Island, Panggang Island and Karang Lebar lagoons and to compare the result of depth estimation from Kd model and derived from Landsat 8 imagery. The measurement of Kd(λ) was carried out using hyperspectral spectroradiometer TriOS-RAMSES with range 320 – 950 nm. The relationship between measurement Kd(λ) on study site with the water constituent was the occurrence of absorption by chlorophyll-a concentration at the blue and green spectral wavelength. Depth estimation using band ratio from Kd(λ) occurred at 442,96 nm and 654,59 nm, which had better relationship with the depth from in-situ measurement compared to the estimation based on Landsat 8 band ratio. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. However, depth estimation based on Kd(λ) ratio was inconsistent due to the bottom albedo reflection because the Kd(λ) measurement was carried out in shallow waters. Estimation of water depth based on Kd(λ) ratio had better results compared to the Landsat 8 band ratio.

Analysis of Propagation of Long Waves in Shallow Water Using the KdV-Based Nonlinear Fourier Transform (KdV-NLFT)

2014 ◽  
Author(s):  
Markus Brühl ◽  
Hocine Oumeraci
Keyword(s):  
Fourier Transform ◽  
Free Surface ◽  
Water Resources ◽  
Shallow Water ◽  
Water Depth ◽  
Shallow Waters ◽  
Nonlinear Phenomenon ◽  
Undular Bore ◽  
Wave Maker ◽  
Nonlinear Fourier Transform

Hydraulic model tests and numerical simulations show that long sinusoidal waves that are generated in very shallow waters are not stable but show modifications of the free surface as function of propagation in time and space. First, with increasing distance from the wave maker the wave becomes asymmetric and develops into a bore-shaped wave. Second, with further increasing distance more and more additional wave crests appear from the front of the bore (undular bore). The shallower the water depth, the more additional wave components can be observed. In extremely shallow water, the periodic sine waves completely disintegrate into periodic trains of solitons. At Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI), TU Braunschweig, a nonlinear Fourier transform based on the Korteweg-deVries equation (KdV-NLFT) is implemented and successfully applied in Brühl [1] that provides an explanation for this nonlinear phenomenon and allows the prediction of the dispersion and propagation of long sinusoidal waves in shallow water.

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