多波束回波强度数据记录方式比较

分析了三种不同多波束测深系统回波强度的记录方式及数据结构,基于各自生成声纳图像的特点规律的差异,按其声纳图像不同用途对多波束测深系统进行了归类,其结果可为用户结合自身需求,正确购置多波束测深系统及合理应用声纳图像提供参考.     

济州岛南部海域海底声呐图像分析与声学底质分类

东海北部外陆架靠近济州岛南部海域,是黄海槽向冲绳海槽延伸的部分,属于黑潮分支黄海暖流的通道入口,分布着脊槽相间的海底底形,对其海底声呐图像的处理分析及声学底质分类的分析研究,有助于了解该通道海底底形表层纹理特征及沉积物分布规律。基于在济州岛南部海域获取的多波束声呐数据,应用图像处理技术和方法,对数据进行了处理,获得了海底声呐影像图,并对其表层纹理特征进行了描述和分析;同时,基于多波束反向散射强度数据,结合19组海底地质取样数据,建立研究区海底反向散射强度与沉积物粒度特征之间的统计关系模型,并以改进的学习向量量化神经网络方法,实现对海底粉砂质砂、黏土质砂以及砂-粉砂-黏土3种底质类型的快速自动分类识别。     

多波束水深测量误差源分析与成果质量评定

结合多波束测深系统在海洋水深测量实际生产中的应用,分析了受复杂海洋动态环境以及仪器自身原因等内外部因素影响易产生的各种粗差和系统性偏差,探讨了适用于多波束测深系统获取的水深测量成果的质量控制和检验指标,制定了涵盖多波束测深数据采集、处理、成果制作、验收等全过程的质量检验方案。     

关于多波束声速剖面改正问题的探讨

简要介绍了声线跟踪计算中比较精确的常梯度声线跟踪算法,针对实际声速剖面测量中可能出现的随机误差和整体偏差两种情况,分别设计了相对应的模拟声速剖面,然后采用常梯度声线跟踪算法计算波束脚印,分析声速剖面误差对波束脚印计算的影响,给出了实际多波束测量作业中声速剖面测定密度和间隔的建议。     

深水多波束声呐测深数据精度评估

多波束测深精度评估是水深测量质量控制的重要方面,静态精度评估与交叉测线动态精度评估能够从不同角度表征测深精度,估计测量样本的综合误差。在实际调查作业过程中,由于缺少水深真值,在进行精度估计时缺少可操作性。本文利用Kongsberg EM120型深水多波束系统的测深数据,基于某一区域的重复测量数据,应用中央波束的水深数据进行静态精度分析;通过引入网格化方法,进行动态水深精度评估分析,并通过偏差分析揭示测量样本的误差分布特征。结果表明,中央波束水深数据静态精度评估与基于网格化方法的动态精度评估具有实际可操作性,其结果能够有效估计测深的综合误差;重复测量数据的偏差分析能够有效展示误差的分布特征。     

Morphologic investigation of “uncharted” seamount from central Indian basin revisited with multibeam sonar system

Morphology of a seamount at 12°35'E and 76°18.5’ and two abyssal hills in its vicinity is described using the Hydrosweep multibeam‐swath bathymetric system. The height of the seamount is 1350 m, and it occupies an area of 330 km². Its basal width is 22.5 km, and the mount has a gentle and longer western flank and a steep and shorter eastern flank. There is a characteristic terracelike feature on the western flank, about 300 m from the top. A caldera is also observed on top of the seamount. Slope angles in this area are high (over 35"). Results of morphologic studies of the seamount from the multibeam survey are comparable to those from a narrow‐beam echosounding survey. The origin of the seamount may be related to the presence of a fracture zone at 75°45'E.     

Acoustic imagery using a multibeam bathymetric system

Historically, measurement and collection of deep‐ocean acoustic imagery are accomplished by towed sidescan systems. Recently, work has been performed to extract acoustic imagery from current hull‐mounted wide‐swath bathymetric sonars with minimal hardware modification. Past work of deriving acoustic imagery from swath sonars has been performed primarily with SeaBeam's sixteen 2^2/3 ° preformed beams. The Navy is investigating the feasibility of extracting an acoustic image from the Sonar Array Survey Systems (SASS), a high‐resolution (1^o beams) wide‐fan (90°) bathymetric system. Due to the large data volume (approximately 1 MB per ping), SASS normally discards the raw acoustic returns once bathymetry is calculated. In early 1991 the Naval Air Development Center (NADC) installed the hardware on board the USNS Maury to capture and record the raw acoustic signal (inphase and quadrature) from the SASS's 144 hydrophones for later inversion to a backscatter image. Preliminary qualitative mosaics of the sidescan images show promising results and warrant further development.     

A New Method of Automatic SVP Optimization Based on MOV Algorithm

We applied the maximum offset of sound velocity algorithm to sound velocity profile streamlining and optimization to overcome multibeam survey and data-processing efficiency problems. The impact of sound velocity profile streamlining on sounding data accuracy is evaluated. By automatically optimizing the threshold, the reduction rate of sound velocity profile data can reach over 90% and the standard deviation percentage error of sounding data can be controlled to within 0.1%. The optimized sound velocity profile data improved the operational efficiency of the multi-beam survey and data postprocessing by 3.4 times, indicating that this algorithm has practical value for engineering applications.     

Robust Automatic Reduction of Multibeam Bathymetric Data Based on M-estimators

Multibeam echosounders have commonly been employed for a wide range of applications including offshore survey, navigation, hydrogeology, and oceanography. Because the tremendous volume of the bathymetric data is demanding for some purposes and requires significant storage space, the data reduction plays a prominent role in practice. Additionally, the multibeam soundings are inevitably contaminated with sporadic outliers, and as such, the data cleaning can be challenging especially in shallow waters. We present a speedily robust method for reliably reducing the volume of the bathymetric data within grid cells. In this respect, robust M-estimators are recursively applied to the data in a patch-wise manner to alleviate the undesirable effects of the outlying observations. Accordingly, the reduced bathymetry is automatically made unaffected by the possible outliers once their equivalent weights have been downweighted. The performance of the presented method has been demonstrated by synthetic datasets and an experimental dataset collected by an ATLAS FS 20/100 kHz shallow-water multibeam echosounder in the offshore waters of Kish wharf. The reliability, efficiency, and capability of the proposed method have been verified, which makes it quite possible to meet the IHO requirements for special-order seafloor mapping.     

TerraSolid与ArcGIS相结合的海量多波束数据成图处理方法

针对海量多波束数据数据量大、处理成图困难的特点,本文提出了利用TerraSolid软件对海量多波束数据进行质量检查与抽稀,再通过ArcGIS软件进行制图处理的方法。实际生产应用证明该方法可靠、方便,提高了作业效率。