Automated trinocular stereo imaging system for three-dimensional surface wave measurements

Wanek, Justin; Wu, Chin H.

doi:10.1016/j.oceaneng.2005.05.006

Cited by 95 publications

(74 citation statements)

References 34 publications

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“…In particular, directional spectra of short gravity waves were estimated from stereo-pairs by Shemdin et al (1988) and Banner et al (1989). Benetazzo (2006) has proposed and tested a Wave Acquisition Stereo System (WASS) for field measurements at the coast, and more recently Bechle and Wu (2011) have studied coastal waves over areas ~3 m 2 using a trinocular system (Wanek and Wu, 2006). Kosnik and Dulov (2011) have estimated sea roughness from stereo images and de Vries et al (2011) have presented a stereo analysis of waves in the surf zone over an area of 1000 m 2 .…”

Section: Introductionmentioning

confidence: 99%

Space–time measurements of oceanic sea states

et al. 2013

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Section: Introductionmentioning

confidence: 99%

Space–time measurements of oceanic sea states

et al. 2013

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“…For example, Shemdin et al (1988) and Banner et al (1989) estimated directional spectra of short gravity waves, and Benetazzo (2006) proposed and optimized a Wave Acquisition Stereo System (WASS) for field measurements at the coast. More recently, Bechle and Wu (2011) have studied coastal waves over areas of ~3 m 2 using a trinocular system (Wanek andWu, 2006), de Vries et al (2011) have presented stereo measurements of waves in the surf zone over an area of -1000 m 2 , and Kosnik and Dulov (2011) have estimated sea roughness from stereo images.…”

Section: Introductionmentioning

confidence: 99%

Offshore stereo measurements of gravity waves

Benetazzo

Fedele

Gallego

et al. 2012

Coastal Engineering

109

104

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Stereo video techniques are effective for estimating the space-time wave dynamics over an area of the ocean. Indeed, a stereo camera view allows retrieval of both spatial and temporal data whose statistical content is richer than that of time series data retrieved from point wave probes. To prove this, we consider an application of the Wave Acquisition Stereo System (WASS) for the analysis of offshore video measurements of gravity waves in the Northern Adriatic Sea. In particular, we deployed WASS at the oceanographic platform Acqua Alta, off the Venice coast, Italy. Three experimental studies were performed, and the overlapping field of view of the acquired stereo images covered an area of approximately 1100 m 2 . Analysis of the WASS measurements show that the sea surface can be accurately estimated in space and time together, yielding associated directional spectra and wave statistics that agree well with theoretical models. From the observed wavenumber-frequency spectrum one can also predict the vertical profile of the current flow underneath the wave surface. Finally, future improvements of WASS and applications are discussed.

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“…First, the so-called interior calibration was used to correct radial and tangential distortions (commonly appeared in the photographs from spherical-lens cameras). The distortion parameters are defined by the collinearity equations can be found in Wanek and Wu [21]. In Figure 5, the parameters, (uc, vc), represent the center of the image; r is the distance from image center to an arbitrary point; (k1, k2) and (p1, p2) are the lens parameters of radial and tangential distortions, respectively.…”

Section: (I) Image Calibrationmentioning

confidence: 99%

“…Two images (at least) were taken from different vantage points to triangulate three-dimensional coordinates of water surface [13,21,23]. Based on the camera orientation Figure 5.…”

Section: (Ii) Image Mappingmentioning

confidence: 99%

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Application of an Automated Discharge Imaging System and LSPIV during Typhoon Events in Taiwan

Huang

Young

Liu

2018

Water

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An automated discharge imaging system (ADIS), which is a non-intrusive and safe approach, was developed for measuring river flows during flash flood events. ADIS consists of dual cameras to capture complete surface images in the near and far fields. Surface velocities are accurately measured using the Large Scale Particle Image Velocimetry (LSPIV) technique. The stream discharges are then obtained from the depth-averaged velocity (based upon an empirical velocity-index relationship) and cross-section area. The ADIS was deployed at the Yu-Feng gauging station in Shimen Reservoir upper catchment, northern Taiwan. For a rigorous validation, surface velocity measurements were conducted using ADIS/LSPIV and other instruments. In terms of the averaged surface velocity, all of the measured results were in good agreement with small differences, i.e., 0.004 to 0.39 m/s and 0.023 to 0.345 m/s when compared to those from acoustic Doppler current profiler (ADCP) and surface velocity radar (SVR), respectively. The ADIS/LSPIV was further applied to measure surface velocities and discharges during typhoon events (i.e., Chan-Hom, Soudelor, Goni, and Dujuan) in 2015. The measured water level and surface velocity both showed rapid increases due to flash floods. The estimated discharges from ADIS/LSPIV and ADCP were compared, presenting good consistency with correlation coefficient R = 0.996 and normalized root mean square error NRMSE = 7.96%. The results of sensitivity analysis indicate that the components till (τ) and roll (θ) of the camera are most sensitive parameters to affect the surface velocity using ADIS/LSPIV. Overall, the ADIS based upon LSPIV technique effectively measures surface velocities for reliable estimations of river discharges during typhoon events.

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Automated trinocular stereo imaging system for three-dimensional surface wave measurements

Cited by 95 publications

References 34 publications

Space–time measurements of oceanic sea states

Space–time measurements of oceanic sea states

Offshore stereo measurements of gravity waves

Application of an Automated Discharge Imaging System and LSPIV during Typhoon Events in Taiwan

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