共查询到20条相似文献,搜索用时 15 毫秒
1.
多波束声呐图像是进行海底底质分类的主要数据源之一,由于受海洋噪声、声波散射和混响、仪器设备等因素影响,其经各项常规改正后仍存在明显残差,突出表现在中央波束区和条带重叠区,难以形成高质量的声呐图像。文中分析了多波束声呐图像残差的成因及影响,提出了一种基于多条带最小二乘拟合的多波束声呐图像残差处理方法。首先,得到相邻声脉冲(ping)信号中央区域、重叠区域以及整体趋势的拟合函数;然后,通过拟合函数计算得到中央和重叠区域的残差改正系数;最后,通过改正系数进行残差改正。实验分析表明,该方法在保留原始细节的基础上,有效削弱了残差对声呐图像的影响,对多波束声呐图像处理具有参考和应用价值。 相似文献
2.
Digital filters designed using wavelet theory are applied to high resolution deep-towed side-scan sonar data from the median valley walls, crestal mountains, and flanks of the Mid-Atlantic Ridge at 29°10 N. With proper tuning, the digital filters are able to identify the location, orientation, length, and width of highly reflective linear features in sonar images. These features are presumed to represent the acoustic backscatter from axis-facing normal faults. The fault locations obtained from the digital filters are well correlated with visual geologic interpretation of the images. The side-scan sonar images are also compared with swath bathymetry from the same area. The digitally filtered bathymetry images contain nine of the eleven faults identified by eye in the detailed geologic interpretation of the side-scan data. Faults with widths (measured perpendicular to their strike) of less than about 150 m are missed in the bathymetry analysis due to the coarser resolution of these data. This digital image processing technique demonstrates the potential of wavelet-based analysis to reduce subjectivity and labor involved in mapping and analyzing topographic features in side-scan sonar and bathymetric image data. 相似文献
3.
4.
5.
6.
7.
8.
9.
This paper reports a comparative study of digital enhancement techniques using spatial filtering to improve the geologic interpretation of side-scan sonar GLORIA images. Seven algorithms for speckle reduction with window sizes of 3×3-7×7 pixel and various numbers of iterations were tested for cosmetic purposes, and also to improve subsequent image processing. The filtered images were evaluated using both quantitative and qualitative techniques. It was determined that a normalized inverse gradient weighted smoothing scheme, with a 3×3 pixel filter and five iterations, allows a significant speckle reduction without blurring the edges in the GLORIA image which correspond to geological structures. Three local contrast enhancement techniques were also tested and evaluated to increase the perception of these geologic structures. Subtracting the gradient magnitude twice, calculated with spatial filters of a 5×5 pixel on smoothed images, was found to enhance most GLORIA images. Texture analysis methods developed for GLORIA images of mid-oceanic ridges and based on edge detection and orientation determination by spatial filtering are also presented. It enables the GLORIA mosaic of the Rodriguez triple junction (Indian Ocean) to be partitioned into regions of preferred orientation corresponding to the different seafloor fabrics generated at each arm of the triple junction 相似文献
10.
The natural motion of a ship at sea produces undesirable effects on sonar displays. To overcome this problem some form of stabilization is desirable. A practical sonar display system, which uses image processing techniques to stabilize the displayed sonar image against rotational motion is described. The stabilization method provides the capability of image enhancement as well as improved image interpretation due to an increased area of view and a geometrically correct conversion to polar display. Details of the three processing stages required in the system are provided. These processes are ship motion analysis, image integration, and polar display conversion. Stabilized results are given for simulated ship motion 相似文献
11.
多波束声呐记录的海底后向散射片段(Snippet)数据处理成角度响应曲线和地理编码(Mosaic)图像可以
帮助识别海底底质类型和反映地貌形态,这一过程包括辐射校正、角度响应改正(AVG)和几何地理编码,但不同的多波束系统硬件在辐射校正和角度响应改正方法上存在差异且传统处理方法忽略了声呐系统本身的指向性模型随时间变化的事实。以声呐方程为基础,针对Kongsberg EM 多波束系统提出了一套完整的Snippet数据处理流程,并分析了各步骤中存在的可变性,给出了每一步的处理建议,最后将此方法应用于EM2040浅水多波束实测数据,并验证了该方法的有效性和实用性。 相似文献
12.
济州岛南部海域海底声呐图像分析与声学底质分类 总被引:2,自引:2,他引:0
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。 相似文献
13.
多波束反向散射强度数据应用广泛,但由于受到角度响应的影响,导致生成的多波束声呐图像质量偏低,且现有角度响应改正方法在复杂海底底质环境下适应性较差。为此本文对散射强度进行分析,给出了两种多波束反向散射强度数据归一化方法,分别为基于高斯拟合以及角度响应的散射强度改正方法,前者主要是基于散射强度的变化规律进行改正,而后者则是基于声波的散射机理进行改正。实验结果表明两种方法较传统改正方法精度均有约30%的提升,并且角度响应方法较高斯拟合方法改正精度更高,但计算效率有所下降。以上实验验证了两种方法的有效性,实现了散射强度数据的归一化,提升了多波束声呐图像的质量。 相似文献
14.
侧扫声纳技术应用日益广泛,已成为海洋测量的重要工具,而去除噪声处理是对侧扫声纳图像进行正确判读的前提。利用小波函数滤波处理的方法,分别采用Haar、Daubechies、Coiflets、Symlets、Discrete Meyer、Biorthogonal、Reverse Biorthogonal等小波函数与中值滤波函数对侧扫声纳图像进行处理,并以平滑指数和边缘保持指数为评价指标,对滤波效果进行定量比较。试验表明,小波函数可以有效地平滑声纳图像,并能保持其较好的边缘效果。 相似文献
15.
16.
Contamination of seismic reflection records at early times by first-order water reverberations can be especially severe during survey operations over hard and flat sea floors on the continental shelf or in lake environments. A new dereverberation scheme based on two classical techniques — predictive deconvolution and velocity filtering — has been developed to address this problem. The techniques are combined spatially to take advantage of their complementary offset- and time-dependent properties. Stage I of the scheme consists of applying predictive deconvolution at short offset. The data are previously conditioned by a normal moveout correction with the water velocity which restores the periodicity of the reverberations in the offset-time plane and enhances the performance of deconvolution. Stage II of the scheme involves velocity filtering in the common-midpoint domain which is particularly effective at long offset where the moveout difference between primary reflections and reverberations is largest. The dereverberation scheme is well suited for the initial processing of large volumes of data due to the general availability of cost-effective deconvolution and velocity filtering algorithms in seismic processing software packages. Practical implementation issues are illustrated by a field example from the GLIMPCE survey in Lake Superior.Lithoprobe Publication No. 475. 相似文献
17.
18.
Experimental bottom relief survey technology and investigation results are presented. Investigations were conducted over about six years at several White-Sea river estuaries onboard the R/V Ecolog. Geomorphology data was obtained using an instrument complex that included an MKS, Microsound side scan sonar, AP-5 acoustic profiler, and LMS-350 echo sounder. ECHOGRAPH and WINRASTR original software was used for data gathering and processing. 相似文献
19.