Inference of manganese nodule coverage from Sea Beam acoustic backscattering data

Geophysics ◽  
1985 ◽  
Vol 50 (6) ◽  
pp. 989-1001 ◽  
Author(s):  
Christian de Moustier
Keyword(s):  
Dynamic Range ◽  
Manganese Nodule ◽  
Ground Truth ◽  
Normal Incidence ◽  
Acoustic Backscattering ◽  
Acoustic Data ◽  
Mining Areas ◽  
Physical Laboratory ◽  
Sea Beam ◽  
Instrument Package

Normal incidence reflectivity from a manganese nodule field was measured with a 12 kHz Sea Beam multibeam echo‐sounding system, aboard the R/V Thomas Washington and used to infer nodule coverage. A reflectivity map of the area was produced using the intensity of the specular return from each ping. The patchiness of the nodule coverage is evidenced by definite highs and lows in the reflectivity pattern. Ground truth was provided by near‐bottom acoustic measurements and photographs taken with the Deep Tow instrument package of the Marine Physical Laboratory. Agreement between the simple nodule coverage predictions from Sea Beam acoustic data and the bottom photographs taken throughout the area is 98 percent. Although the Sea Beam system is limited in its dynamic range, this paper shows that it can be used very effectively to determine both topography and nodule coverage in potential mining areas.

scholarly journals Quantifying and reducing the surface blind zone and the seabed dead zone using new technology

2009 ◽  
Vol 66 (6) ◽  
pp. 1370-1376 ◽  
Author(s):  
Atle Totland ◽  
Geir O. Johansen ◽  
Olav R. Godø ◽  
Egil Ona ◽  
Terje Torkelsen
Keyword(s):  
New Technologies ◽  
New Technology ◽  
Dead Zone ◽  
Autonomous Systems ◽  
Ecosystem Dynamics ◽  
Potential Measurement ◽  
Acoustic Backscattering ◽  
Acoustic Data ◽  
Blind Zone ◽  
Measurement Biases

Abstract Totland, A., Johansen, G. O., Godø, O. R., Ona, E., and Torkelsen, T. 2009. Quantifying and reducing the surface blind zone and the seabed dead zone using new technology. – ICES Journal of Marine Science, 66: 1370–1376. The surface blind zone and the seabed dead zone are unobservable with hull-mounted acoustic systems. These constraints may seriously limit the effectiveness of acoustic observations in studies of ecosystem dynamics. In this paper, new technologies are used to make observations in these boundary zones, by augmenting conventional acoustic observations from transducers mounted in a retractable keel with simultaneous observations from two autonomous acoustic systems, one sampling the surface blind zone and the other the seabed dead zone. These observations to some extent overlap in depth, which allows comparisons between data collected with the vessel and the corresponding data from the two autonomous systems. The main targets of the investigation were young-of-the-year gadoids in the surface blind zone and older cod at least partly in the seabed dead zone. Species and their sizes were identified from trawl samples. The advantages and limitations of using new autonomous equipment for quantifying the acoustic backscattering within otherwise unobservable zones are discussed. The magnitudes of potential measurement biases in acoustic data collected with the vessel are also estimated for this survey.

Expanding dynamic range in a single-shot image through a sparse grid of low exposure pixels

2020 ◽  
Vol 2020 (7) ◽  
pp. 229-1-229-7
Author(s):  
Leon Eisemann ◽  
Jan Froehlich ◽  
Axel Hartz ◽  
Johannes Maucher
Keyword(s):  
Dynamic Range ◽  
Ground Truth ◽  
Sparse Grid ◽  
Single Shot ◽  
High Luminance ◽  
Multiple Exposures ◽  
Low Exposure ◽  
Camera Sensors

Camera sensors are physically restricted in the amount of luminance which can be captured at once. To achieve a higher dynamic range, multiple exposures are typically combined. This method comes with several disadvantages, like temporal or alignment aliasing. Hence, we propose a method to preserve high luminance information in a single-shot image. By introducing a grid of highlight preserving pixels, which equals 1% of the total amount of pixels, we are able to sustain information directly incamera for later processing. To provide evidence, that this number of pixels is enough for gaining additional dynamic range, we use a U-Net for reconstruction. For training, we make use of the HDR+ dataset, which we augment to simulate our proposed grid. We demonstrate that our approach can preserve high luminance information, which can be used for a visually convincing reconstruction, close to the ground truth.

scholarly journals An evaluation of supervised and unsupervised classification techniques for marine benthic habitat mapping using multibeam echosounder data

2014 ◽  
Vol 72 (5) ◽  
pp. 1498-1513 ◽  
Author(s):  
Jay Calvert ◽  
James Asa Strong ◽  
Matthew Service ◽  
Chris McGonigle ◽  
Rory Quinn
Keyword(s):  
Selection Process ◽  
Ground Truth ◽  
Unsupervised Classification ◽  
Horizontal Resolution ◽  
Habitat Mapping ◽  
Benthic Habitat ◽  
Marine Habitat ◽  
Ground Truth Data ◽  
Multibeam Echosounder ◽  
Acoustic Data

Abstract Marine habitat mapping provides information on seabed substrata and faunal community structure to users including research scientists, conservation organizations, and policy makers. Full-coverage acoustic data are frequently used for habitat mapping in combination with video ground-truth data in either a supervised or unsupervised classification. In this investigation, video ground-truth data with a camera footprint of 1 m2 were classified to level 4 of the European Nature Information System habitat classification scheme. Acoustic data with a horizontal resolution of 1 m2 were collected over an area of 130 km2 using a multibeam echosounder, and processed to provide bathymetry and backscatter data. Bathymetric derivatives including eastness, northness, slope, topographic roughness index, vector rugosity measure, and two measures of curvature were created. A feature selection process based on Kruskal–Wallis and post hoc pairwise testing was used to select environmental variables able to discriminate ground-truth classes. Subsequently, three datasets were formed: backscatter alone (BS), backscatter combined with bathymetry and derivatives (BSDER), and bathymetry and derivatives alone (DER). Two classifications were performed on each of the datasets to produce habitat maps: maximum likelihood supervised classification (MLC) and ISO Cluster unsupervised classification. Accuracy of the supervised habitat maps was assessed using total agreement, quantity disagreement, and allocation disagreement. Agreement in the unsupervised maps was assessed using the Cramer's V coefficient. Choice of input data produced large differences in the accuracy of the supervised maps, but did not have the same effect on the unsupervised maps. Accuracies were 46, 56, and 49% when calculated using the sample and 52, 65, and 51% when using an unbiased estimate of the population for the BS, BSDER, and DER maps, respectively. Cramer's V was 0.371, 0.417, and 0.366 for the BS, BSDER, and DER maps, respectively.

Approaches to Acoustic Backscattering Measurements From the Deep Seafloor

1988 ◽  
Vol 110 (2) ◽  
pp. 77-84 ◽  
Author(s):  
C. de Moustier
Keyword(s):  
Remote Sensing ◽  
Measuring Instruments ◽  
Physical Constraints ◽  
Acoustic Backscattering ◽  
Quantitative Measurements ◽  
Geological Processes ◽  
Sonar Systems ◽  
Sea Beam ◽  
Primary Means ◽  
Qualitative Measure

Because the average ocean depth is four kilometers, seafloor investigations are mostly remote sensing operations. The primary means to determine the morphology, the structure, and the texture of the seafloor are acoustic. This paper considers the current seafloor remote sensing approaches involving acoustic backscattering. The physical constraints imposed by the ocean as a propagation medium, by the seafloor as a backscattering boundary, and by the measuring instruments are briefly reviewed. The sonar systems currently used by the oceanographic community for deep seafloor acoustic backscattering measurements deal with these constraints differently, depending on their specific application and on whether they are towed behind a ship or mounted on her hull. Towed sidescan systems such as Gloria II (U.K.), the Sea Mapping and Remote Characterization (Sea MARC) I and II, the Deep Tow system of the Marine Physical Laboratory (MPL), and hull-mounted systems, such as Swathmap all give a qualitative measure of backscattering by converting echo amplitudes to gray levels to produce a sidescan image of the seafloor. A new approach is presented which uses a Sea Beam multibeam echo-sounder to produce similar acoustic images. Quantitative measurements of backscattering have been attempted in recent experiments using the Deep Tow system and Sea Beam. Such measurements provide some insight into the geological processes responsible for the acoustic backscatter, with useful applications for geologists as well as designers and operators of bottom-interacting sonars.

Acoustic characterization of Mysis relicta at multiple frequencies

2008 ◽  
Vol 65 (12) ◽  
pp. 2769-2779 ◽  
Author(s):  
Lars G. Rudstam ◽  
Frank R. Knudsen ◽  
Helge Balk ◽  
Gideon Gal ◽  
Brent T. Boscarino ◽  
...  
Keyword(s):  
Average Length ◽  
Target Strength ◽  
Mysis Relicta ◽  
Detection Range ◽  
Acoustic Backscattering ◽  
Acoustic Data ◽  
Acoustic Characterization ◽  
Lower Maximum ◽  
Multiple Frequencies

We measured acoustic backscattering from Mysis relicta , a common invertebrate in northern lakes, using five frequencies (38, 120, 200, 430, and 710 kHz). Acoustic backscattering from mysids was highest at 430 kHz and lowest at 38 kHz (19 dB lower). Maximum difference between the four other frequencies was 5.2 dB. Mysid target strength (TS) ranged from –80.1 dB at 430 kHz to –99.4 dB at 38 kHz (12 mm average length, range 5–21 mm). A theoretical scattering model (Stanton’s fluid-like, bent-cylinder model) predicted TS within 0.3–1.9 dB of observed TS for the different frequencies. The detection range was lowest at 38 and 710 kHz and greatest at 120 and 200 kHz. Fish were common above the mysid layer and produced higher acoustic backscattering at 38 kHz than at the other frequencies. A combination of 38 kHz and 120 or 200 kHz provides a strong contrast between mysid and fish acoustic backscattering that would help separate these groups using acoustic data.

scholarly journals Stochastic formalism-based seafloor feature discrimination using multifractality of time-dependent acoustic backscatter

2014 ◽  
Vol 21 (1) ◽  
pp. 101-113 ◽  
Author(s):  
K. Haris ◽  
B. Chakraborty
Keyword(s):  
Ground Truth ◽  
Normal Incidence ◽  
Dual Frequency ◽  
Scale Invariant ◽  
Subtle Difference ◽  
Single Beam ◽  
First Order ◽  
Fine Sediments ◽  
Analysis Technique ◽  
Invariant Properties

Abstract. Dual-frequency echo-envelope data acquired using the normal-incidence single-beam echosounder system (SBES) have been examined to study its scale invariant properties. The scaling and multifractality of the SBES echo envelopes (at 33 and 210 kHz) were validated by applying a stochastic-based multifractal analysis technique. The analyses carried out substantiate the hierarchy of multiplicative cascade dynamics in the echo envelopes, demonstrating a first-order multifractal phase transition. The resulting scale invariant parameters (α, C1, and H) establish gainful information that can facilitate distinctive delineation of the sediment provinces in the central part of the western continental shelf of India. The universal multifractal parameters among the coarse and fine sediments exhibit subtle difference in α and H, whereas the codimension parameter C1 representing the sparseness of the data varies. The C1 values are well clustered at both the acoustic frequencies, demarcating the coarse and fine sediment provinces. Statistically significant correlations are noticeable between the computed C1 values and the ground truth sediment information. The variations in the multifractal parameters and their behavior with respect to the ground truth sediment information are in good corroboration with the previously estimated sediment geoacoustic inversion results obtained at the same locations.

scholarly journals Acoustic Observation of Zooplankton Using High Frequency Sonar (Observasi Akustik Zooplankton Menggunakan Sonar Frekuensi Tinggi)

2015 ◽  
Vol 20 (2) ◽  
pp. 61 ◽  
Author(s):  
Henry M Manik
Keyword(s):  
High Frequency ◽  
Acoustic Scattering ◽  
Temporal Distribution ◽  
Acoustic Backscattering ◽  
Acoustic Data ◽  
Accuracy And Precision ◽  
Acoustic Observation ◽  
Physical Information ◽  
Acoustic Surveys ◽  
Biological Organisms

Underwater acoustic sampling techniques provide an advantage over traditional net-sampling for zooplankton research. The research presents a methodology for extracting both biological and physical information from high frequency sonar. These methods can easily provide the information that will improve our understanding of the spatial and temporal distribution of zooplankton. Measured acoustic data converted into biological organisms and numerical physics-based scattering models were used in this research. The numerical backscattering process was modeled using the Distorted-Wave Born Approximation (DWBA) to predict the amount of sound scattered by a weakly scattering animal. Both acoustic measurement and DWBA modeled scattering patterns showed that acoustic scattering levels are highly dependent on zooplankton orientation. The acoustic backscattering from zooplankton depends on the material properties (i.e. the sound speed and density of the zooplankton), the shape and size, and the orientation relative to the incident acoustic wave. DWBA model significantly improve the accuracy and precision of zooplankton acoustic surveys. Zooplankton data measurement and DWBA model analysis provide a basis for future acoustical studies.

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