| 基于侧扫声呐影像的南海珊瑚礁沉船及周边地形重建 |
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| 引用本文： | 刘小菊,施祺,杨红强,周胜男.基于侧扫声呐影像的南海珊瑚礁沉船及周边地形重建[J].热带地理,2020,40(2):278-288. |
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| 作者姓名： | 刘小菊 施祺 杨红强 周胜男 |
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| 作者单位： | 1.中国科学院南海海洋研究所,中国科学院边缘海与大洋地质重点实验室,广州 5103012.中国科学院南海生态环境工程创新研究院,广州 5103013.中国科学院南沙海洋生态环境实验站,海南 三沙 5731994.南方海洋科学与工程广东省实验室（广州）,广州 5114585.中国科学院大学,北京 100049 |
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| 基金项目： | 中国科学院战略性先导科技专项(A类)(XDA13010103);中国科学院南海生态环境工程创新研究院创新发展基金项目(ISEE2018PY02,ISEE2018PY01)。 |
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| 摘 要： | 利用南海某珊瑚礁区所获得的一艘沉船的单幅侧扫声呐影像,定量重建了沉船及其周边地形。沉船区侧扫声呐数据经过格式转换、影像生成、水体去除、影像增益校正和坐标转换等预处理后,采用明暗恢复形状（Shape From Shading, SFS）方法反演声呐影像的水深,获得沉船区的水下地形数据,重建了该区域的三维地形地貌。结果显示,沉船位于珊瑚礁西侧礁坡区,该区为典型的礁坡地貌形态,由东向西水深递增,变化于-1.8~-165.4 m之间,按水深和坡度的不同可划分为地势较平缓的两级阶地和地势陡峭的两级坡地。沉船坐底于礁坡第二级阶地（宽约87 m,平均水深约-26.7 m,平均坡度约5.7°）,船体呈EES—WWN走向,长约45 m,宽约9 m,高约4 m,排水量估计为500~600 t,船体残破。利用侧扫声呐影像开展地形地貌的定量反演和重建是对侧扫声呐影像地形地貌定性分析的有效补充,能更全面、更详细地揭示珊瑚礁地形地貌的特征。
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| 关 键 词： | 南海 珊瑚礁 侧扫声呐 三维重建 沉船 |
| 收稿时间： | 2019-11-14 |
Reconstruction of Shipwreck and Surrounding Relief at a Coral Reef in the South China Sea Based on Side Scan Sonar Image |
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| Liu Xiaoju,Shi Qi,Yang Hongqiang,Zhou Shengnan.Reconstruction of Shipwreck and Surrounding Relief at a Coral Reef in the South China Sea Based on Side Scan Sonar Image[J].Tropical Geography,2020,40(2):278-288. |
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| Authors: | Liu Xiaoju Shi Qi Yang Hongqiang Zhou Shengnan |
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| Institution: | (Key Laboratory of Ocean and Marginal Sea Geology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China;Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China;Nansha Marine Ecological and Environmental Research Station,Chinese Academy of Sciences,Sansha 573199,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;University of Chinese Academy of Sciences,Beijing 100049,China) |
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| Abstract: | As sonic imaging instrument,side scan sonar is widely used in the qualitative detection and recognition of underwater landforms and objects.Some researchers have attempted to quantitatively reconstruct underwater landforms using the Shape From Shading(SFS)method,which is based on the principle of computer vision.At present,it is sometimes used in the investigation of coral reefs in China.In the present study,a quantitative reconstruction of shipwreck and its surrounding relief is carried out at a coral reef in the South China Sea based on single side scan sonar image.After the pre-processing steps of data format conversion,image generation,water removal,image gain and correction,and coordinate conversion,the side scan sonar image of the shipwreck area was used to retrieve the underwater topographic data.The study involved using an SFS algorithm based on minimization approach with the measured bathymetric data as the initial topographic condition to reconstruct the three-dimensional relief of the shipwreck and surrounding area.The mean absolute error was 0.77 m and the mean relative error between the retrieved and measured water depths was 4.5%,revealing the topographic and geomorphic features of the shipwreck area.The results show that the shipwreck area is located on the western side of the coral reef and has the typical geomorphologic form of a reef slope with water depth increasing from-1.8 m to-165.4 m from east to west.It can be divided into two relatively planar terraces and two steep slopes according to the water depth and slope gradient.The first terrace is approximately 46 m wide,with a mean depth of approximately-4.1 m and a mean gradient of approximately 1.4°;the first slope is approximately 35 m wide,with a mean depth of approximately-16.1 m and a mean gradient of approximately 28.8°.The second terrace is approximately 87 m wide,with a mean depth of approximately-26.7 m and a mean gradient of approximately 5.7°;the second slope is approximately 90 m wide,with a mean depth of approximately-63.3 m and a mean gradient of approximately 39.0°.The shipwreck is located on the second terrace of the reef slope.The shipwreck lies in EES-WWN orientation and is approximately 45 m long,9 m wide,4 m high,with a tonnage of approximately 500-600 tons.However,the shipwreck is no longer intact.The quantitative inversion and reconstruction of underwater landforms using side scan sonar images is an effective complement to the qualitative analysis of the images and can reveal the topographic and geomorphic characteristics of the coral reef in more comprehensive and detailed ways.In the future,the quantitative analysis method of side scan sonar imaging will have widespread applications in the investigation of topographic reconstructions,substrate types and coral community distributions,human activity footprint monitoring,and identification of special objects such as submerged reefs and shipwrecks. |
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| Keywords: | South China Sea coral reef side scan sonar 3D reconstruction shipwreck |
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