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海岸线是海岛海岸带研究的基础要素,对于海岸带资源开发利用具有重要意义。遥感技术凭借其宏观、多光谱且周期短等特点成为快速提取海岸线的重要技术手段。本文采用高分辨率遥感数据WorldView-2对海岸线两侧地物的表观反射率进行分析,并开展特征分析,构建了海岸线提取指数。在此基础上,进一步结合纹理特征提取方法,成功提取了马来西亚棉花岛的海岸线。基于线目标匹配法对提取结果进行精度评价,其中长度误差为-1.38%,在缓冲半径为6个像素单位时,完整度为96.96%,正确度为95.37%。结果表明,用该方法提取的海岸线精度较高,可满足遥感调查的需要。 相似文献
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Efficient and accurate access to coastal land cover information is of great significance for marine disaster prevention and mitigation.Although the popular and common sensors of land resource satellites provide free and valuable images to map the land cover,coastal areas often encounter significant cloud cover,especially in tropical areas,which makes the classification in those areas non-ideal.To solve this problem,we proposed a framework of combining medium-resolution optical images and synthetic aperture radar(SAR)data with the recently popular object-based image analysis(OBIA)method and used the Landsat Operational Land Imager(OLI)and Phased Array type L-band Synthetic Aperture Radar(PALSAR)images acquired in Singapore in 2017 as a case study.We designed experiments to confirm two critical factors of this framework:one is the segmentation scale that determines the average object size,and the other is the classification feature.Accuracy assessments of the land cover indicated that the optimal segmentation scale was between 40 and 80,and the features of the combination of OLI and SAR resulted in higher accuracy than any individual features,especially in areas with cloud cover.Based on the land cover generated by this framework,we assessed the vulnerability of the marine disasters of Singapore in 2008 and 2017 and found that the high-vulnerability areas mainly located in the southeast and increased by 118.97 km2 over the past decade.To clarify the disaster response plan for different geographical environments,we classified risk based on altitude and distance from shore.The newly increased high-vulnerability regions within 4 km offshore and below 30 m above sea level are at high risk;these regions may need to focus on strengthening disaster prevention construction.This study serves as a typical example of using remote sensing techniques for the vulnerability assessment of marine disasters,especially those in cloudy coastal areas. 相似文献
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海岸线是十分重要的自然资源,海岸线的变化会影响生态平衡与人们的生活。本文以浙江省秀山岛1970、1980、2003、2008和2014年的遥感影像作为数据源,利用遥感和GIS技术方法,并采用DSAS的岸线分析方法揭示了秀山岛近50 a来岸线的时空变化规律。结果表明:在自然和人为的双重因素影响下,秀山岛的自然岸线和人工岸线发生大规模的变化,岸线长度总体上是减少的,共减少4 226 m,新增陆域面积2.491 km2;其中人工岸线减少了4 046 m,海塘面积增加1.971 km2,表现为大规模的向海推进,时空变化显著;自然岸线减少了214 m,主要是沙质岸线和淤泥质岸线的变化,整体表现为岸线小规模的后退,但是局部地区有向海推进的现象。 相似文献
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Todd L. Walton Jr 《Ocean Engineering》2000,27(1):1811
Investigation of shoreline change signals in the presence of possible non-stationarity is attempted via Karhunen–Loeve filtering to separate the actual shoreline signal change from that of random noise. Interpretation is made of the signal and noise normalized covariance and spectra to help in delineating natural change versus man-made change patterns for a section of shoreline where a navigation channel existed over a portion of the shoreline history. 相似文献
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借着光学图象增强方法和数字图象处理技术,我们对莱州湾沿岸34幅卫片进行了图象处理与解译。经现场验证后,结合地面资料,最后完成了该项研究报告及有关图件36幅。研究报告较全面地总结了遥感技术在莱州湾海岸带地质地貌调查中所取得的成果。这些成果包括;莱州湾地区的地貌特征及其成因类型;莱州湾潮间带的地貌分带及全新世海侵范围;莱州湾沿岸黄河入海泥沙的扩散范围及强度分布;莱州湾岸线动态变化及岸滩稳定性的研究;遙感图象处理方法在菜州湾海岸带调查中的应用研究等。从中可以看出,遥感图象处理技术,在海岸河口地区动态分析研究中的价值 相似文献
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为探究冬季不同背景风场下黑潮锋影响边界层云的机理,采用高分辨率卫星数据和再分析数据,研究了冬季海面背景风为垂直(西北风)和平行(东北风)东海黑潮海表面温度锋(黑潮锋)条件下,边界层云对黑潮锋的响应。结果表明:背景风垂直黑潮锋情况下,黑潮锋强迫的边界层内次级环流明显,黑潮锋暖水侧海面冷平流强,海气温差增大,海气界面潜热感热通量增大,海气界面不稳定性增大,产生上升运动,云底高度抬升。上升运动在边界层底向南北两侧辐散,在冷水侧产生下沉运动与500 hPa高压下沉叠加,使局地云量明显减少,形成晴空少云区(云洞)。在暖水侧以南的下沉支叠加云顶上的下沉运动和边界层退耦效应共同作用,产生另一个云洞。气压调整机制为次级环流产生的主要原因。背景风平行黑潮锋情况下,海面空气温度平流作用小,暖水侧海气温差较小,虽然海洋仍然加热大气,但海气界面不稳定较弱,湍流增强使云底高度抬升,垂直混合机制为该湍流增强的主要原因。 相似文献
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提出一种基于光学原理的Fourier频率域随机谱隐秘信息加载与增量补偿系统,并给出一种隐秘信息的加载方式,可实现光学图像信息隐藏.宿主图像经过随机相位调制后进行Fourier变换得到频率域的随机谱,在此随机谱上加载隐秘信息,同时,系统对由隐秘信息的加入所产生的影响进行补偿.利用该系统所得到的载体图像未经正确的密钥-随机相位-调制时,隐秘信息将弥散在载体图像的Fourier频率域空间,具有较好的不可检测性.此外,即使攻击者知道隐秘信息的存在甚至知道隐藏方法,但在不知道密钥的情况下,依然无法破解隐秘信息的内容 相似文献
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E. A. Sharkov 《Izvestiya Atmospheric and Oceanic Physics》2011,47(9):1057-1071
The generation and evolution of atmospheric catastrophes (tropical cyclones) represents a very serious and still unresolved
problem for mankind. The existing physical hypotheses and theoretical approaches which form the basis for a number of space
programs on the investigation of physical conditions for the genesis and evolution of tropical cyclones are critically analyzed.
The most significant stages of the history of development of the scientific aspects and concepts about tropical cyclones,
which are reflected in the pages of the Investigation of the Earth from the Space journal, are observed. The significance and role of remote (optical, infrared, and microwave) sensing in the evolution of
scientific views are analyzed. The fundamental contribution which Russian researchers and, first of all, specialists of the
Space Research Institute, Russian Academy of Sciences, as well as Russian developers of space missions and remote instrumentation,
have made to the present-day understanding of the problem and to the formation of the present-day image of microwave remote
sensing (RS) of the excited atmosphere is emphasized. 相似文献
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为加强对江苏省海岸带的保护和开发利用,文章基于卫星遥感影像,通过提取瞬时水边线和推算潮位特征线,分析1984—2016年江苏省海岸线和沿海滩涂的变迁。研究结果表明:江苏省自然岸线逐渐减少,人工岸线大幅增加,海岸线明显向海推进;淤长岸段主要分布在辐射沙洲北翼的射阳河口至川东港南,冲刷岸段主要分布在废黄河三角洲的灌河口北至中山河口南和扁担河口北至双洋河口南,全省海岸淤长长度和平均淤长速率均大幅下降;沿海各地的潮间带平均宽度均有不同程度的缩短,滩涂围垦强度大是重要影响因素。 相似文献
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Several methods (Spectral Angle Mapper, first derivatives, spectral clustering) were used to test the possibility of discriminating live corals at the species level by using reflectance spectra obtained by close range underwater remote sensing. The Spectral Angle Mapper used with an in situ spectral library of 73 coral colonies recognised all corals correctly in an artificial remote sensing image created from the same coral spectra. The results did not change when “grey” noise was added to each pixel in the artificial image or when the artificial image was made from reflectance spectra modelled through a 5-m water column. The results showed that the within-species variability in optical properties of a set of four coral species, for which at least three different specimens were measured, was as high as between-species variability. Thus, it is highly unlikely that hard corals can be discriminated at a species level by means of remote sensing. Cluster analysis showed that it is difficult to recognise corals also at the genus level (Acropora vs. non-Acropora) based on their reflectance spectra. However, visual inspection of the coral spectra and clustering analysis suggest that it is possible to separate three main optical types of corals: green, blue, and brown corals. This may form the basis for an optical classification of corals that is more suited for remote sensing than traditional taxonomy. 相似文献
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一种融合纹理特征与NDVI的随机森林海冰精细分类方法 总被引:1,自引:0,他引:1
海冰的精准分类对于掌握海冰生长发育状况,保障航海安全等具有重要意义。由于受数据源和分类方法等影响,使得海冰分类精度提高受限。本文面向高空间分辨率的光学遥感影像,提出了一种融合纹理特征和归一化差分植被指数(NDVI)的海冰精准分类方法,运用随机森林分类器构建海冰分类方法。以青岛胶州湾为实验区,高分二号(GF-2)为实验数据,进行了海冰类型提取,并与其他分类方法进行对比。结果显示:针对GF-2高分辨率光学遥感数据,融合纹理特征和NDVI的随机森林方法,相比于传统的随机森林、支持向量机、自动决策树和融合纹理特征的最大似然分类方法,总体分类精度分别提高13.70%、11.60%、19.22%、29.37%。Kappa系数分别提高0.16、0.13、0.22、0.44。相比于融合纹理特征和归一化水指数(NDWI)的随机森林方法,总体分类精度提高了9.67%,Kappa系数提高了0.09。这表明本文构建的海冰分类方法可有效提高海冰分类精度,为海冰的精确分类提供了一种有效的技术手段。 相似文献
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针对热红外遥感图像由于低对比度、条带噪声、低空间分辨率等特点而导致的检测效果不佳问题,提出了一种近岸舰船目标尺度自适应选择分层多阈值检测方法。采用舰船模板图像尺度归一化高斯拉普拉斯函数取极大值准则进行尺度自适应选择,利用所选的高斯多尺度空间差分多阈值筛选进行近岸舰船检测,并根据不同类型舰船模板图像尺度和分块数选择对热红外图像舰船目标检测的影响进行验证实验。实验结果表明:所提方法能根据模板尺度特征滤除相似区域,通过设置合理尺度和阈值参数能实现有效检测,且具有一定的抗噪能力。 相似文献
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Dailiang Wang 《Marine Geodesy》2019,42(3):286-315
Although ridge tracing has the advantages of continuity and high positioning accuracy compared with other edge-based methods, it is difficult to use ridge tracing to extract coastlines from Synthetic Aperture Radar (SAR) images because of the speckle noise that occurs in SAR images. This paper presents a new coastline extraction method for SAR images based on a more robust ridge tracing method. First, according to the statistical properties of the pixel intensities in the land and sea regions in a SAR image, an edge magnitude map that characterizes the boundary between them is produced by the ratio of the variance to the mean such that the magnitude at the land-sea boundary is much higher than that at other locations. Second, the pixel with the maximum magnitude in the map is adopted as the starting point for tracing, and strip windows, which reduce tracing failures, are adopted to obtain different average magnitudes corresponding to the eight neighborhood pixels around the starting point. Then, the neighborhood pixel with the maximum magnitude is adopted as the next tracing point. The above procedure is repeated to determine the direction of the next point. This process achieves part of the tracing operation. The complete coastline is then extracted by performing the other part of the tracing operation. The experimental results show that the proposed method is more robust than traditional methods, and we demonstrate its effectiveness with RADARSAT-2 and Sentinel-1A data. 相似文献