The Effect of Sunglint Correction for Estimating Water Depth Using Rationing, Thresholding, and Mean Value Algorithms

Rekayasa ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 39-48
Author(s):  
Luhur Moekti Prayogo ◽  
Abdul Basith
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Mean Value ◽  
Point Of View ◽  
Water Object ◽  
Depth Data ◽  
Central Java ◽  
Depth Extraction ◽  
The Mean ◽  
Shallow Water Depth

Satellite-Derived Bathymetry (SDB) is an alternative for obtaining shallow water depth data. The existence of images with various resolutions, the availability of a complete image band can develop the extraction results. This method is based on the principle of the satellite's visible band to estimate water depth. The mapping of shallow water depth is dependent on water conditions, both its brightness and surface. When the sensor senses a water object, the reflected reflection comes from the surface, and some sensors cannot penetrate the water object. The sun's position and the sensor's point of view when sensing it results in interference from the water surface (Sunglint). The sunglint effect on the image can be reduced by performing RGB band correction with NIR Infrared. This study aims to demonstrate the effect of Sunglint's correction on three SDB approaches, namely Thresholding, Rationing, and Mean Value on Worldview 3 imagery in Karimunjawa Islands, Central Java. This study's results indicate that the Sunglint correction on Worldview 3 imagery affects the depth extraction results. The best results are shown by Sunglint's correction using the Thresholding approach (B2-B7), which produces the best correlation with R2 of 0.7364 and (B7-B2) with R2 = 0.7351. Contrastingly, the lowest correlation was generated using the Mean Value ((B2 + B7) / 2) approach without Sunglint's correction with R2 = 0.4015. So this research proves that the Worldview 3 image with Sunglint correction can provide bathymetry data, especially in shallow waters.

Stability of offshore structures in shallow water depth

2011 ◽  
Vol 2 (2) ◽  
pp. 320-333
Author(s):  
F. Van den Abeele ◽  
J. Vande Voorde
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Fossil Fuels ◽  
Oil And Gas ◽  
Structural Response ◽  
Offshore Structures ◽  
Exploration And Production ◽  
Subsea Pipelines ◽  
Wave Induced ◽  
Shallow Water Depth

The worldwide demand for energy, and in particular fossil fuels, keeps pushing the boundaries of offshoreengineering. Oil and gas majors are conducting their exploration and production activities in remotelocations and water depths exceeding 3000 meters. Such challenging conditions call for enhancedengineering techniques to cope with the risks of collapse, fatigue and pressure containment.On the other hand, offshore structures in shallow water depth (up to 100 meter) require a different anddedicated approach. Such structures are less prone to unstable collapse, but are often subjected to higherflow velocities, induced by both tides and waves. In this paper, numerical tools and utilities to study thestability of offshore structures in shallow water depth are reviewed, and three case studies are provided.First, the Coupled Eulerian Lagrangian (CEL) approach is demonstrated to combine the effects of fluid flowon the structural response of offshore structures. This approach is used to predict fluid flow aroundsubmersible platforms and jack-up rigs.Then, a Computational Fluid Dynamics (CFD) analysis is performed to calculate the turbulent Von Karmanstreet in the wake of subsea structures. At higher Reynolds numbers, this turbulent flow can give rise tovortex shedding and hence cyclic loading. Fluid structure interaction is applied to investigate the dynamicsof submarine risers, and evaluate the susceptibility of vortex induced vibrations.As a third case study, a hydrodynamic analysis is conducted to assess the combined effects of steadycurrent and oscillatory wave-induced flow on submerged structures. At the end of this paper, such ananalysis is performed to calculate drag, lift and inertia forces on partially buried subsea pipelines.

Polarization lidar for shallow water depth measurement

2010 ◽  
Vol 49 (36) ◽  
pp. 6995 ◽  
Author(s):  
Steven Mitchell ◽  
Jeffrey P. Thayer ◽  
Matthew Hayman
Keyword(s):  
Shallow Water ◽  
Water Depth ◽  
Depth Measurement ◽  
Shallow Water Depth

scholarly journals Generalized Lyzenga's Predictor of Shallow Water Depth for Multispectral Satellite Imagery

2013 ◽  
Vol 36 (4) ◽  
pp. 365-376 ◽  
Author(s):  
Ariyo Kanno ◽  
Yoji Tanaka ◽  
Akira Kurosawa ◽  
Masahiko Sekine
Keyword(s):  
Shallow Water ◽  
Satellite Imagery ◽  
Water Depth ◽  
Multispectral Satellite Imagery ◽  
Shallow Water Depth

scholarly journals Observations and a Model of the Mean Circulation over the Middle Atlantic Bight Continental Shelf

2008 ◽  
Vol 38 (6) ◽  
pp. 1203-1221 ◽  
Author(s):  
Steven J. Lentz
Keyword(s):  
Pressure Gradient ◽  
Continental Shelf ◽  
Shallow Water ◽  
Water Depth ◽  
Circulation Pattern ◽  
Near Surface ◽  
Middle Atlantic ◽  
The Mean ◽  
Offshore Flow ◽  
Mean Circulation

Abstract Analyses of current time series longer than 200 days from 33 sites over the Middle Atlantic Bight continental shelf reveal a consistent mean circulation pattern. The mean depth-averaged flow is equatorward, alongshelf, and increases with increasing water depth from 3 cm s−1 at the 15-m isobath to 10 cm s−1 at the 100-m isobath. The mean cross-shelf circulation exhibits a consistent cross-shelf and vertical structure. The near-surface flow is typically offshore (positive, range −3 to 6 cm s−1). The interior flow is onshore and remarkably constant (−0.2 to −1.4 cm s−1). The near-bottom flow increases linearly with increasing water depth from −1 cm s−1 (onshore) in shallow water to 4 cm s−1 (offshore) at the 250-m isobath over the slope, with the direction reversal near the 50-m isobath. A steady, two-dimensional model (no along-isobath variations in the flow) reproduces the main features of the observed circulation pattern. The depth-averaged alongshelf flow is primarily driven by an alongshelf pressure gradient (sea surface slope of 3.7 × 10−8 increasing to the north) and an opposing mean wind stress that also drives the near-surface offshore flow. The alongshelf pressure gradient accounts for both the increase in the alongshelf flow with water depth and the geostrophic balance onshore flow in the interior. The increase in the near-bottom offshore flow with water depth is due to the change in the relative magnitude of the contributions from the geostrophic onshore flow that dominates in shallow water and the offshore flow driven by the bottom stress that dominates in deeper water.

scholarly journals Penile length of newborns and children in Surakarta, Indonesia

2013 ◽  
Vol 53 (2) ◽  
pp. 65 ◽  
Author(s):  
Annang Giri Moelyo ◽  
Melita Widyastuti
Keyword(s):  
Down Syndrome ◽  
Gestational Age ◽  
Ambiguous Genitalia ◽  
Mean Value ◽  
Normal Range ◽  
Penile Length ◽  
Central Java ◽  
Majority Population ◽  
The Mean ◽  
Diagnosis Age

Background Penile length is a factor for assessing abnormalities inexternal genitalia. To diagnose micropenis, a condition in whichpenile length is < - 2.5 standard deviations (SD), a reference isrequired for diagnosis. Age and race/ethnic groups are factorsthat contribute to normal penile length. To date, Indon esia doesnot have such a reference for normal penile length in newbornsand children.Objective To assess normal penile length in newborns and childrenin Surakarta, Central Java, in which the majority population isofJavanese ethnicity.Methods We studied male newborns and children who werepatients in Moewardi Hospital from January 2011 to January2012. We included males aged 0-18 years whose parents providedinformed consent. We excluded children with undescendedtestis, hypospadia, ambiguous genitalia, con genital anomalies,or syndromes (such as Down syndrome). For penile len gthmeasurements, we stretched the flaccid penis, depressed thepubic fat and placed a wooden spatula vertically along the dorsalpenis. The penile length was measured from the penile baseto the tip of the glans excluding the prepuce. Measurementswere performed three times and a mean value was calculatedfor each subject.Results Of the 300 subjects, 100 were newborns and 200 werechildren aged 1 month - 18 years. Two hundred ninety-six subjects(98.7%) were Javanese. The mean penile lengths of preterm(gestational age 30-36 weeks) and term (gestational age > 36weeks) newborns were 1.88 (SD 0.14) cm and 2.3 7 (SD 0.26) cm,respectively. The mean penile lengths by age groupings were asfollows: 0-<6 months, 2.67 (SD 0.58) cm; 6- < 12 months, 2.67(SD 0.58) cm; 1- <3 years, 2.80 (SD 0.84) cm; 3-<5 years, 3 .50(SD 0.55) cm; 5- <7 years, 3 .50 (SD 0.71) cm; 7-<9 years, 3 .85(SD 0.53 ) cm; 9-<ll years, 4.50 (SD 0.71) cm; 11-< 13 years,4.63 (SD 1.13) cm; 13-< 15 years, 5.53 (SD 1.45) cm; and 15-18years, 6.16 (SD 1.19) cm.Conclusion Normal penile length in boys in Surakarta is smallerthan the normal range reference currently in use.

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