Application of Riemann Distance in Depth Estimation of Active Sonar Targets in Shallow Waters

ABSTRACT. Studies in shallow waters pointed out that the acoustic wave interference patterns have potential application in a broad range of problems in underwater acoustics such as: passive sonar, active sonar, array processing, time-reverse mirrors and geoacoustic inversion. For shallow waters underwater sound waveguides, the main features of this research is interference pattern or “striations” obtained by means of Frequency-time or Frequency-distance spectrograms. This work aims to characterize these interference pattern or striations related to “invariant” parameter β. The theory is developed based on real underwater waveguide. The present results confirm that the parameter β is frequency dependent and at high frequencies it tends to the unity. In another words, far from the waveguide cut-off frequency the present real waveguides could be treated by an ideal waveguide. Besides, in this approximation it is possible to make source-receiver passive distance predictions based on the related interference pattern.Keywords: underwater acoustic, waveguide, interference pattern.RESUMO. Estudos em águas rasas apontam que os padrões de interferência de ondas acústicas têm aplicação potencial em uma ampla gama de problemas de acústica submarina, tais como: sonar passivo, sonar ativo, processamento de arrays, espelhos de reversão temporal e inversão geoacústica. O foco principal desta pesquisa é o padrão de interferência ou estrias obtidas por meio de espectrogramas e gráficos no plano de Frequências e Distâncias. Este trabalho tem como objetivo caracterizar estes padrões de interferência ou estrias com o parâmetro invariante β. A teoria é desenvolvida com base em um guia de onda real. Os resultados deste estudo confirmam que o parâmetro β é dependente da frequência e, em altas frequências, tende à unidade. Em outras palavras, longe da frequência de corte, o comportamento do guia de onda real é semelhante ao guia de onda ideal. Além disso, nesta aproximação, é possível fazer previsões de distância passiva entre o receptor e a fonte com base no padrão de interferência.Palavras-chave: acústica submarina, guia de ondas, padrão de interferência.

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The influence of array vertical directivity patterns on bottom reverberation for mid to high frequency active sonar working in littoral shallow waters

OCEANS'11 MTS/IEEE KONA ◽

10.23919/oceans.2011.6106944 ◽

2011 ◽

Author(s):

Songwen Li ◽

Zhaowen Meng

Keyword(s):

High Frequency ◽

Shallow Waters ◽

Active Sonar ◽

Directivity Patterns

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Matched-field depth estimation for active sonar

The Journal of the Acoustical Society of America ◽

10.1121/1.1634277 ◽

2004 ◽

Vol 115 (2) ◽

pp. 620-629 ◽

Cited By ~ 8

Author(s):

Granger Hickman ◽

Jeffrey L. Krolik

Keyword(s):

Depth Estimation ◽

Active Sonar

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Correcting Image Refraction: Towards Accurate Aerial Image-Based Bathymetry Mapping in Shallow Waters

Remote Sensing ◽

10.3390/rs12020322 ◽

2020 ◽

Vol 12 (2) ◽

pp. 322 ◽

Cited By ~ 7

Author(s):

Panagiotis Agrafiotis ◽

Konstantinos Karantzalos ◽

Andreas Georgopoulos ◽

Dimitrios Skarlatos

Keyword(s):

Visual Information ◽

Depth Estimation ◽

Point Clouds ◽

Aerial Image ◽

Shallow Waters ◽

Image Correction ◽

Sea State ◽

Sea Bottom ◽

Dense Point ◽

Free Set

Although aerial image-based bathymetric mapping can provide, unlike acoustic or LiDAR (Light Detection and Ranging) sensors, both water depth and visual information, water refraction poses significant challenges for accurate depth estimation. In order to tackle this challenge, we propose an image correction methodology, which first exploits recent machine learning procedures that recover depth from image-based dense point clouds and then corrects refraction on the original imaging dataset. This way, the structure from motion (SfM) and multi-view stereo (MVS) processing pipelines are executed on a refraction-free set of aerial datasets, resulting in highly accurate bathymetric maps. Performed experiments and validation were based on datasets acquired during optimal sea state conditions and derived from four different test-sites characterized by excellent sea bottom visibility and textured seabed. Results demonstrated the high potential of our approach, both in terms of bathymetric accuracy, as well as texture and orthoimage quality.

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The importance of Atmospheric Correction for Airborne Hyperspectral Remote Sensing of Shallow Waters. Application to Depth Estimation

10.5194/amt-2017-37 ◽

2017 ◽

Author(s):

Elena Castillo-López ◽

Jose Antonio Dominguez ◽

Raúl Pereda ◽

Julio Manuel de Luis ◽

Ruben Pérez ◽

...

Keyword(s):

Shallow Water ◽

Water Depth ◽

Accurate Determination ◽

Atmospheric Correction ◽

Principal Component ◽

Depth Estimation ◽

Correction Method ◽

Shallow Waters ◽

Depth Information ◽

Cross Track

Abstract. Abstract. Accurate determination of water depth is indispensable in multiple aspects of civil engineering (dock construction, dikes, submarines outfalls, trench control, etc.). According to the final objective, different accuracies will be required. Accuracy in bathymetric information is highly dependent on the atmospheric correction made to the imagery. The reduction of effects such as glint and cross track illumination in shallow-water areas with homogeneous improves the results of the depth estimations. The aim of this work is to assess the best atmospheric correction method for the estimation of depth in shallow waters. This paper addresses the use of hyperspectral imagery to quantitative bathymetric mapping, and explores one of the most common problems when attempting to extract depth information in conditions of variable water types and bottom reflectances. The current work assesses the accuracy of some classical bathymetric algorithms (Polcyn-Lyzenga, Philpot, Benny-Dawson, Hamilton, Principal Component Analysis) when four different atmospheric correction methods are applied and water depth is derived. This work shows the importance of atmospheric correction in order to depth estimation in shallow waters. None atmospheric correction is valid for all type of coastal waters but in heterogeneous shallow water, the model of atmospheric correction 6S offers good results.

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Target-depth estimation in active sonar: Cramer–Rao bounds for a bilinear sound-speed profile

The Journal of the Acoustical Society of America ◽

10.1121/1.4962495 ◽

2016 ◽

Vol 140 (3) ◽

pp. 1771-1782 ◽

Cited By ~ 5

Author(s):

Alexis Mours ◽

Cornel Ioana ◽

Jérôme I. Mars ◽

Nicolas F. Josso ◽

Yves Doisy

Keyword(s):

Sound Speed ◽

Depth Estimation ◽

Speed Profile ◽

Sound Speed Profile ◽

Active Sonar ◽

Target Depth

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The importance of atmospheric correction for airborne hyperspectral remote sensing of shallow waters: application to depth estimation

Atmospheric Measurement Techniques ◽

10.5194/amt-10-3919-2017 ◽

2017 ◽

Vol 10 (10) ◽

pp. 3919-3929 ◽

Cited By ~ 5

Author(s):

Elena Castillo-López ◽

Jose Antonio Dominguez ◽

Raúl Pereda ◽

Julio Manuel de Luis ◽

Ruben Pérez ◽

...

Keyword(s):

Shallow Water ◽

Water Depth ◽

Accurate Determination ◽

Atmospheric Correction ◽

Principal Component ◽

Depth Estimation ◽

Correction Method ◽

Shallow Waters ◽

Depth Information ◽

Cross Track

Abstract. Accurate determination of water depth is indispensable in multiple aspects of civil engineering (dock construction, dikes, submarines outfalls, trench control, etc.). To determine the type of atmospheric correction most appropriate for the depth estimation, different accuracies are required. Accuracy in bathymetric information is highly dependent on the atmospheric correction made to the imagery. The reduction of effects such as glint and cross-track illumination in homogeneous shallow-water areas improves the results of the depth estimations. The aim of this work is to assess the best atmospheric correction method for the estimation of depth in shallow waters, considering that reflectance values cannot be greater than 1.5 % because otherwise the background would not be seen. This paper addresses the use of hyperspectral imagery to quantitative bathymetric mapping and explores one of the most common problems when attempting to extract depth information in conditions of variable water types and bottom reflectances. The current work assesses the accuracy of some classical bathymetric algorithms (Polcyn–Lyzenga, Philpot, Benny–Dawson, Hamilton, principal component analysis) when four different atmospheric correction methods are applied and water depth is derived. No atmospheric correction is valid for all type of coastal waters, but in heterogeneous shallow water the model of atmospheric correction 6S offers good results.

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IN-SITU MEASUREMENT OF DIFFUSE ATTENUATION COEFFICIENT AND ITS RELATIONSHIP WITH WATER CONSTITUENT AND DEPTH ESTIMATION OF SHALLOW WATERS BY REMOTE SENSING TECHNIQUE

International Journal of Remote Sensing and Earth Sciences (IJReSES) ◽

10.30536/j.ijreses.2017.v14.a2682 ◽

2017 ◽

Vol 14 (1) ◽

pp. 47

Author(s):

Budhi Agung Prasetyo ◽

Vincentius Paulus Siregar ◽

Syamsul Bahri Agus ◽

Wikanti Asriningrum

Keyword(s):

Attenuation Coefficient ◽

Water Depth ◽

Depth Estimation ◽

In Situ Measurement ◽

Shallow Waters ◽

Landsat 8 ◽

Band Ratio ◽

Diffuse Attenuation Coefficient ◽

The Relationship

Diffuse attenuation coefficient, Kd(λ), has an empirical relationship with water depth, thus potentially to be used to estimate the depth of the water based on the light penetration in the water column. The aim of this research is to assess the relationship of diffuse attenuation coefficient with the water constituent and its relationship to estimate the depth of shallow waters of Air Island, Panggang Island and Karang Lebar lagoons and to compare the result of depth estimation from Kd model and derived from Landsat 8 imagery. The measurement of Kd(λ) was carried out using hyperspectral spectroradiometer TriOS-RAMSES with range 320 – 950 nm. The relationship between measurement Kd(λ) on study site with the water constituent was the occurrence of absorption by chlorophyll-a concentration at the blue and green spectral wavelength. Depth estimation using band ratio from Kd(λ) occurred at 442,96 nm and 654,59 nm, which had better relationship with the depth from in-situ measurement compared to the estimation based on Landsat 8 band ratio. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. Depth estimated based on Kd(λ) ratio and in-situ measurement are not significantly different statistically. However, depth estimation based on Kd(λ) ratio was inconsistent due to the bottom albedo reflection because the Kd(λ) measurement was carried out in shallow waters. Estimation of water depth based on Kd(λ) ratio had better results compared to the Landsat 8 band ratio.

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Pemetaan Pulau Kecil Gelasa Kabupaten Bangka Tengah

Journal of Tropical Marine Science ◽

10.33019/jour.trop.mar.sci.v2i1.909 ◽

2019 ◽

Vol 2 (1) ◽

pp. 11-14

Author(s):

Wahyu Adi

Keyword(s):

Coral Reefs ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Image Interpretation ◽

Vegetation Coverage ◽

Small Island ◽

Shallow Waters ◽

Small Islands ◽

Seagrass Beds ◽

Cover Density

Pulau Kecil Gelasa merupakan daerah yang belum banyak diteliti. Pemetaan ekosistem di pulau kecil dilakukan dengan bantuan citra Advanced Land Observing Satellite (ALOS). Penelitian terdahulu diketahui bahwa ALOS memiliki kemampuan memetakan terumbu karang dan padang lamun di perairan dangkal serta mampu memetakan kerapatan penutupan vegetasi. Metode interpretasi citra menggunakan alogaritma indeks vegetasi pada citra ALOS yaitu NDVI (Normalized Difference Vegetation Index), serta pendekatan Lyzengga untuk mengkoreksi kolom perairan. Hasil penelitian didapatkan luasan Padang Lamun di perairan dangkal 41,99 Ha, luasan Terumbu Karang 125,57 Ha. Hasil NDVI di daratan/ pulau kecil Gelasa untuk Vegetasi Rapat seluas 47,62 Ha; luasan penutupan Vegetasi Sedang 105,86 Ha; dan penutupan Vegetasi Jarang adalah 34,24 Ha. Small Island Gelasa rarely studied. Mapping ecosystems on small islands with the image of Advanced Land Observing Satellite (ALOS). Previous research has found that ALOS has the ability to map coral reefs and seagrass beds in shallow water, and is able to map vegetation cover density. The method of image interpretation uses the vegetation index algorithm in the ALOS image, NDVI (Normalized Difference Vegetation Index), and the Lyzengga approach to correct the water column. The results of the study were obtained in the area of Seagrass Padang in the shallow waters of 41.99 ha, the area of coral reefs was 125.57 ha. NDVI results on land / small islands Gelasa for dense vegetation of 47.62 ha; area of Medium Vegetation coverage 105.86 Ha; and the coverage of Rare Vegetation is 34.24 Ha.

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