Characterization of the two-dimensional roughness of wave-rippled sea floors using digital photogrammetry

Lyons, Anthony P.; Fox, Warren L. J.; Hasiotis, T.; Pouliquen, E.

doi:10.1109/joe.2002.1040935

Cited by 54 publications

(34 citation statements)

References 16 publications

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“…As a consequence of the poor visibility and between adjacent ridges of 1.92 cm and height of about 1 cm. less-than-pristine sand sea floor encountered during SAX04, The spacing was chosen to approximate half of a digital stereo photography was planned to be conducted by divers on re-creations of the manipulations when water clarity From the digital stereo photographs the 3D surface of the sea floor can be realized; from the 3D realization a 2D roughness power spectrum can be estimated; from the roughness power spectrum the spectral exponent and spectral strength parameters corresponding to the slope and intercept of regression lines calculated at the appropriate azimuths of the roughness orientations can be derived [3]; and from the two parameters describing the roughness spectrum at the appropriate orientations inputs to acoustic scattering models can be determined [4]. Ultimately, the predictions of the scattering models can be compared with the acoustic scattering data collected during SAX04.…”

Section: Report Date (Dd-mm-yyyy)mentioning

confidence: 99%

“…Comparison of the left and right registered z images with automatic stereo correlation, using a technique called area-based matching, results in the derivation of the N relative height differences of the photographed sea floor [3]. under-water visibility near the sea floor at the SAX04 site, rendering the photographs useless for photogrammetry.…”

Section: Wmentioning

confidence: 99%

“…Digital Calibration photos were taken in five positions (flat; and redinthpoogasuelsfr oormeryDgtl Citi oned peftrighotos we botae win h fiespoitions (at;e ad Elevation Models composed of 3D arrays of position (x, y) and tilted left, right, top and bottom) with respect to the fixed hih z auswr osrce rmatcreaino iia geometryheight (z) values were constructed from autocorrelation of digital between the real comer and the re-projected corer at each grd image pairs from the Vortex Springs site. 2D roughness power spectra are estimated from the array values, taking care to taper the vertex for all positions and duplicates indicates a relatively data array to reduce spectral leakage [3]. These 2D roughness tight cluster with some outlying values (Figs.…”

Section: Wmentioning

confidence: 99%

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Roughness Spectra and Acoustic Response from a Diver-Manipulated Sea Floor

et al. 2006

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The public reporting burden for this collection of information is estimated to average 1 hour per response, Including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information It it does not display a currently valid OMB control number.PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. Abstract-A digital stereo photogrammetric system was de-wavelength corresponding to an acoustic frequency of 45 signed and implemented to measure seafloor roughness in coastal kHz-i.e., the Bragg wavelength for 45 kHz. Ripple-like sands. High-resolution images that achieve more than four patterns were created for treatments parallel, perpendicular, pixels/mm in either the horizontal or vertical dimension are created by two cameras sealed in watertight housings and and 30 degrees to the transmitted direction of acoustic energy actuated simultaneously by a scuba diver. A Digital Elevation from a variable frequency (20 to 150 kHz) transducer mounted Model (DEM) of the photographed sea floor is created from on a 4.8-m-high, moveable, underwater tower. Divers made digital autocorrelation of left and right paired images. The DEM the ripple patterns in a 2 m-by-2 m quadrat 10 m from the is used to estimate a 2D roughness power spectrum, from which tower resulting in are derived parameters of the spectral exponent and spectral , a grazing angle of about 28 degrees to the strength that are used as inputs in high-frequency acoustic desired target.Upon creating the microroughness, and scattering models.subsequently thereafter at various time intervals, divers were to document the seafloor morphology with underwaterAn important component of the Sediment Acoustic Prior to and during SAX04 Hurricanes Frances, Ivan, and EXperiment 2004 (SAX04) conducted in the northeastern Gulf Jeanne, as well as Tropical Storm Matthew, interrupted the of Mexico during September-November of 2004 was to collection of data. Furthermore, underwater visibility during investigate the acoustic scattering from the rippled sea floor, the experiments was hampered by material suspended in the In situ manipulative experiments were conducted to determine water from these storms that rendered photogrammetry the effects of dynamic seafloor roughness on high-frequency ineffectual. In addition to the lack of water clarity, another acoustic scattering, with particular emphasis on the effects of obstacle encountered was a result of t...

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Section: Report Date (Dd-mm-yyyy)mentioning

confidence: 99%

Section: Wmentioning

confidence: 99%

Section: Wmentioning

confidence: 99%

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Roughness Spectra and Acoustic Response from a Diver-Manipulated Sea Floor

et al. 2006

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“…Photographs captured using the NURC photogrammetry system were calibrated and processed according to standard photogrammetric methods [5] to produce surface height fields of the seafloor. A number of the results exhibited significant errors due to the presence of fish and poor water quality.…”

Section: Work Completedmentioning

confidence: 99%

Seafloor Scattering in Shallow Water Environments

Gerig

Bradley²

2013

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense. Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188). 1215 Jefferson Davis Highway. Suite 1204, Arlington. VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

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“…In this paper, the main concern is to better understand how an anisotropic rough surface can impact the acoustic propagation and scattering. The small slope approximation allows us to modify directly the height statistics, either by using true measurements of a rough surface [21] or by using theoretical model via the height covariance function of the seabed to describe its roughness. This modelling approach differs from many computations where anisotropy is directly implemented in the scattered field.…”

Section: Introductionmentioning

confidence: 99%

High Frequency Roughness Scattering from Various Rough Surfaces: Theory and Laboratory Experiments

Jaud¹,

Sessarego²,

Gervaise³

et al. 2012

OJA

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The scattering strength of isotropic and anisotropic rough surfaces was experimentally and theoretically investigated for high frequencies about 500 kHz. Emphasis was placed on studying the response from three two-dimensional rough surfaces which roughness was either isotropic (characterized by a Gaussian distribution) or anisotropic (characterized by a modified-sine surface). Theoretical predictions rely on the first-order small slope approximation either including a Gaussian structure function or a quasi-periodic structure function. The combination of true data and theoretical results indicates the importance of taking into account the anisotropy of a surface in a scattering prediction process. It is shown that the scattering strength varies a lot depending on the propagation plane. In the longitudinal direction of ripples, scattering strength is mostly in the specular direction, whereas in the transversal direction of the ripples, the scattering strength is spread in a very different way related to the particular features of the ripples, with several maxima and minima independent of the specular direction. Contrary to the isotropic surface, the scattering strength from an anisotropic rough surface is modified from one propagation plane to another, which explains why the entire rough surface should be taken into account without any simplification as it is often seen when dealing with scattering models. Compared to such a surface, positions of the emitter and of the receiver are naturally significant when measuring scattering strength.

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Characterization of the two-dimensional roughness of wave-rippled sea floors using digital photogrammetry

Cited by 54 publications

References 16 publications

Roughness Spectra and Acoustic Response from a Diver-Manipulated Sea Floor

Roughness Spectra and Acoustic Response from a Diver-Manipulated Sea Floor

Seafloor Scattering in Shallow Water Environments

High Frequency Roughness Scattering from Various Rough Surfaces: Theory and Laboratory Experiments

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