Measurements of short water waves using stereo matched image sequences

Benetazzo, Alvise

doi:10.1016/j.coastaleng.2006.06.012

Cited by 152 publications

(167 citation statements)

References 13 publications

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“…As regard to vertical resolution, the WASS system is intrinsically a high-resolution system, because the Z-coordinate is a continuous function of both left and right image coordinates as well as internal/external parameters. On the other hand, the accuracy in measuring the wave surface elevation is defined for a given WASS configuration (see Benetazzo, 2006;Benetazzo et al, 2012), and it was estimated equal to 0.01 m and 0.04 m for Acqua Alta and Crimean experiments respectively. At the present stage of WASS development, specular reflections restricted the application of stereo methods to conditions with limited sun glitter.…”

Section: Wass Deployments and Data Acquisitionmentioning

confidence: 99%

“…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%

“…Only at large spatial scales, Synthetic Aperture Radar (SAR), or Interferometric SAR (INSAR) provides sufficient resolution for measuring waves longer than 100 m (see, e.g., Dankert et al, 2003). At smaller scales, video techniques are effective to correctly estimate the space-time dynamics and associated spectral properties (see, for example, Benetazzo, 2006). In particular, stereo cameras can be exploited to retrieve both spatial and temporal data whose statistical content is richer than that of a time series retrieved from wave gauges (Fedele et al, 2011b;Gallego et al, 2011;Benetazzo et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…In practice, stereopairs are acquired simultaneously and the geometry of the stereo system is defined so to minimize errors due to sea surface specularities (Jahne, 1993). Epipolar methods are traditionally used for the reconstruction of the water surface (Mat et al, 2004; see also Benetazzo, 2006), and recently variational-based techniques have been proposed to solve for the stereo problem (see for example, Gallego et al, 2011). In particular, epipolarbased techniques consist in finding pixel correspondences in the two synchronized images by a pixel-by-pixel-based search that is computationally expensive.…”

Section: Introductionmentioning

confidence: 99%

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Space–time measurements of oceanic sea states

et al. 2013

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Section: Wass Deployments and Data Acquisitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Space–time measurements of oceanic sea states

et al. 2013

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“…Indeed, a stereo camera view provides both spatial and temporal data whose statistical content is richer than that of time series retrieved from wave gauges (Benetazzo, 2006;Fedele et al, 2012Fedele et al, , 2011Gallego et al, 2011). Since the water surface is a specular object in rapid movement, it is convenient to acquire stereo-pairs simultaneously, and the geometry of the stereo system is designed to minimize errors due to sea surface specularities (Jahne, 1993).…”

Section: Introductionmentioning

confidence: 99%

Offshore stereo measurements of gravity waves

Benetazzo

Fedele

Gallego

et al. 2012

Coastal Engineering

116

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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Observations of surface waves interacting with ice using stereo imaging

Campbell

Bechle

2014

JGR Oceans

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A powerful Automated Trinocular Stereo Imaging System (ATSIS) is used to remotely measure waves interacting with three distinct ice types: brash, frazil, and pancake. ATSIS is improved with a phaseonly correlation matching algorithm and parallel computation to provide high spatial and temporal resolution 3-D profiles of the water/ice surface, from which the wavelength, frequency, and energy flux are calculated. Alongshore spatial frequency distributions show that pancake and frazil ices differentially attenuate at a greater rate for higher-frequency waves, causing a decrease in mean frequency. In contrast, wave propagation through brash ice causes a rapid increase in the dominant wave frequency, which may be caused by nonlinear energy transfer to higher frequencies due to collisions between the brash ice particles. Consistent to the results in frequency, the wavelengths in pancake and frazil ices increase but decrease in brash ice. The total wave energy fluxes decrease exponentially in both pancake and frazil ice, whereas the overall energy flux remain constant in the brash ice due to thin layer thickness. The spatial energy flux distributions also reveal that wave reflection occurs at the boundary of each ice layer, with reflection coefficient decaying exponentially away from the ice interface. Reflection is the strongest at the pancake/ice-free and frazil/brash interfaces and the weakest at the brash/ice-free interface. These high resolution observations measured by ATSIS demonstrate the spatially variable nature of waves propagating through ice.

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Measurements of short water waves using stereo matched image sequences

Cited by 152 publications

References 13 publications

Space–time measurements of oceanic sea states

Space–time measurements of oceanic sea states

Offshore stereo measurements of gravity waves

Observations of surface waves interacting with ice using stereo imaging

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