共查询到20条相似文献，搜索用时 515 毫秒
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本文以深圳公明水库6个中小型土石坝为试验区，利用10景1 m分辨率升降轨X波段TerraSAR影像和坝体附近连续气象站的降雨量数据，研究了坝体表面相干性的时序变化与雷达本地入射角及降雨的关系。试验结果表明，混凝土面板和草坡平均相干性均会随本地入射角增加而减小，同时，草坡表面平均相干性在有微小降雨的情况下就会快速下降0.1~0.2，差分干涉图的噪声增大；混凝土面板对微小的降雨敏感度小，但是在暴雨情况下将导致其表面完全失相干。上述结果表明，针对中小土石坝坡体变形监测应当顾及坝体的坡度及入射角选择合适的雷达成像参数，同时应充分利用降雨资料评估干涉图失相干情况，剔除噪声数据。 相似文献
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2008年11月10日,青海省大柴旦地区发生了Mw6.3级地震。本文利用EnviSat卫星升降轨SAR数据和差分干涉测量技术提取了同震形变场,基于均匀位错模型反演确定了地震断层参数,然后利用格网迭代搜索法确定了较优断层倾角,同时基于非均匀位错模型获得了精细滑动分布。结果表明,地震使得上盘区域沿降轨、升轨视线向分别产生最大约8.5cm、10cm的抬升;较优断层倾角为47.9°;地震滑动未延伸至地表,主要发生在地下8.2~23.7km深度范围内,最大和平均滑动量为0.5m和0.19m,平均滑动角为104.9°。反演的地震矩为3.74×1018 N·m,矩震级为Mw6.35。 相似文献
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Soil moisture is one of the most important parameter which controls the growth of the vegetation. For accurate data and sufficient information to increase food production, remote sensing technique is highly useful. This paper deals with the bistatic microwave response of spinach and spinach covered soil moisture at various growth stages on X-band if the frequency spectrum. The microwave response of spinach in different stages of growth have been studied in terms of scattering co-efficient (σ°). The look angle effect on σ° is observed for like polarization i.e. (VV-and-HH) only. A linear regression analysis has been done between the vegetation covered soil moisture and scattering co-efficient. It provides an idea that VV-polarization is more sensitive than HH-polarizalion for vegetation covered soil moisture and best suitable look angle for observing vegetation covered soil moisture is less than 40°(θ<40°). 相似文献
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《制图学和地理信息科学》2013,40(3):173-185
Few studies have compared algorithms for mapping surface slope and aspect from digital elevation models. Those studies that have compared these algorithms treat slope and aspect angles independently. The evaluation and comparison of surface orientation algorithms may also be conducted by treating slope and aspect as characteristics of a bi-directional vector normal to the surface. Such a comparison is more appropriate for selecting an accurate surface orientation algorithm for applications that use bi-directional measurements, such as modeling solar radiation or removing the topographic effect from remotely sensed imagery. This study empirically compared the slope angle and bi-directional surface angle estimated from five slope/aspect algorithms using a synthetic terrain surface and an actual terrain surface. The most accurate algorithm is consistently that which uses only the four nearest neighboring elevations in the grid. 相似文献
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使用ERS-1/2干涉测量SAR数据生成DEM 总被引：12，自引：2，他引：12
干涉合成孔径雷达（ＩＮＳＡＲ）数据已被证明能生产精确的数据高程模型（ＤＥＭ），我们已开发了从单视ＳＡＲ复影像数据自动生成数字高程模型的新软件，基于ＳＡＲ多视强度影像的最小二乘曩像匹配被用于复影像对的配准，达到很高的配准精度（０．０１～０．０５像元精度）。一种新的计算目标点３维坐标（Ｘ，Ｙ，Ｚ）的方程还被提出，卫星轨道，姿态和基线参数以及相位常数被纳入在方程中并被表示了时间的线性函数，利用至少６个地面控制点能够同时估算这些参数，本文还给出了意大利埃特地区ＥＲＳ－１／２ＳＡＲ数据处理结果。 相似文献
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星载SAR水下地形和水深遥感的最佳雷达系统参数模拟 总被引：12，自引：1，他引：11
根据星载合成孔径雷达 (SAR)浅海水下地形和水深成像机理 ,建立了浅海水下地形和水深雷达后向散射截面仿真模型。该模型包括奈维 斯托克斯方程、谱作用量平衡方程和雷达后向散射模式。利用该模型仿真结果 ,探讨了不同波段 (P、L、C和X)、不同极化 (VV和HH)和不同入射角 (2 0°— 70°)的星载SAR测量浅海水下地形和水深的能力。研究结果表明 ,浅海水下地形和水深遥感的最佳波段为P波段 ,L波段次之 ,C波段比X波段要好一些。VV极化SAR的测量能力要强于HH极化。 2 0°— 40°是星载SAR测量浅海水下地形和水深的最佳入射角范围。 相似文献
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K. S. Rao T. J. Majumdar D. S. Kamat 《Journal of the Indian Society of Remote Sensing》1984,12(2):53-58
A method has been developed to study the alternate mode BHASKARA SAMIR data with reference to a cartographic referencing system of India. The look angle dependence of the brightness temperature over sea region has been clearly depicted. The change in brightness temperature due to snow/ice in Himalayan region is also identified. A sharp variation of brightness temperature values has been observed at the land-sea crossings. 相似文献
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在经典的走滑位移公式的基础上进行改进, 引入断层倾角信息, 使其反映了走滑断层倾角对地表形变的影响。由于断层倾角的存在使得震间位移曲线的中心是以断层面闭锁-滑动分界在地表的投影为中心, 并且此处形变变化最大; 公式中的倾角项表示拟合的断层倾角, 体现了断层出露地表处与断层闭锁-滑动分界的整体偏移, 其值往往小于近地表倾角测量值。以改进的公式作为断层剖面分析的拟合公式, 应用于汶川地震前后川滇块体东边界主要走滑断裂形变特征的剖面分析研究中, 得到的拟合结果与其他方法得到的结果具有较好的一致性。改进公式比原公式更客观地反映了断层的形变状态, 但由于针对单条断层的剖面拟合受多种因素的影响, 拟合结果需结合实际情况作进一步分析。 相似文献
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新几何光学核驱动BRDF模型反演地表反照率的算法 总被引：13，自引：3，他引：13
MODIS的反照率和二向反射产品由基于核驱动模型的AMBRALS程序提供。目前 AMBRALS算法系统中所用的描述几何光学散射的核为LiSparseR核。新提出的一个几何光学核－LiTransit核兼有LiSparse核向LiDense核过渡的优点，比LiSparseR核更符合几何光学模型的基本原理。验证结果表明：与LiSparseR核比较，RossThick-LiTransit的核组合更能反映直入扇出反照率随太阳天顶角变化的趋势。因此在下一代的AMBRALS算法系统中，将用新的LiTransit核取代LiSparseR核。目前AMBRALS算法系统为了快速处理每天大量的数据，用多项式拟合核的半球积分。因此，为了替换LiSparseR核时，同时又不影响整个算法的系统性，本文研究了LiTransit核的多项式拟合。结果表明：拟合的多项式与核半球积分的相关性很好。 相似文献
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An alternative approach to determine critical angle of contrast reversal and surface roughness of oil slicks under sunglint 总被引：1，自引：0，他引：1
Yansha Wen Mengqiu Wang Shaojie Sun Minwei Zhang Zhihua Mao 《International Journal of Digital Earth》2018,11(9):972-979
The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint. Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks. Although it’s difficult to determine a certain critical angle, the potential critical angle range help to improve the estimation accuracy. In this study, the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer (MODIS). The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter. On the basis of the histograms of the brightness values of the delineated oil slicks, the potential range of the critical angle was determined, and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range. This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater. 相似文献
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主要研究星载重复轨道干涉测量技术的原理、数据处理以及其在地表形变监测中的应用。采用ENVISAT ASAR影像作为实验数据，围绕D—InSAR数据处理过程中的关键技术这一主线，对其中的干涉复图像对的配准、干涉图的生成、去平地效应、差分、提取地表形变等内容进行了深入的探讨。 相似文献
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High-frequency (HF) bistatic Doppler cross sections of the ocean surface are examined with respect to their dependency on the bistatic angle. Previously derived results which incorporate a pulsed dipole source and two orders of scatter are considered. It is trivially seen that the first-order result has a linear dependence on the cosine of the bistatic angle. The second-order echo accounts for a double scatter of incident radiation from first-order surface waves - the so-called electromagnetic term - and a single scatter from a second-order ocean wave. The latter, generally referred to as the second-order hydrodynamic term because it originates from coupling between first-order ocean waves, predominates the Doppler continuum in most regions of interest. The analysis presented here verifies that in addition to a cosine-dependent reduction in cross section magnitude with increasing bistatic angle, both components of the second-order scatter tend to zero under the condition of near-forward scatter for bistatic HF radar operation. Of course, this imposes practical limitations on the region over which a bistatically configured HF radar system may be used to remotely sense ocean surface parameters. 相似文献
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《ISPRS Journal of Photogrammetry and Remote Sensing》1999,54(5-6):360-373
Just as refraction moves the apparent positions of stars from their true ones, it slightly distorts the view of Earth from space, as well as affecting the angle at which sunlight or moonlight illuminates its surface. The astronomer's problem is to correct the apparent position of a star for refraction, relating the position as observed from Earth to the true position. By contrast, the space observer's problem is to obtain the true (refracted) surface zenith angle z′ of illumination or of viewing, when the zenith angle z0 of the ray in space is known, and to correct for the apparent horizontal displacement of the surface point being viewed. This paper solves the problem of the refraction angle for a spherical atmosphere by a simple, analytic solution, depending only on the surface index of refraction μ0 namely: sin(z0)=μ0 sin(z′). The problem of the apparent horizontal displacement of the point viewed is also solved analytically, but approximately, because the result depends weakly on an assumed vertical structure of the atmosphere. The results are useful primarily in cases where observation must be done at large zenith angle, or low Sun angle. 相似文献
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S. Saran G. Sterk P. J. van Oevelen V. K. Dadhwal 《Journal of the Indian Society of Remote Sensing》2012,40(3):541-550
Soil moisture estimation is considered to be one of the important parameters in hydrological studies. The extraction of information on near surface soil moisture from the synthetic aperture radar is well established. The available Advanced Synthetic Aperture Radar (ASAR) data onboard ENVISAT with multi-incidence and multi-polarization mode for soil moisture estimation on sloping terrain was investigated. Empirical models were developed to estimate near surface soil moisture in the fallow agricultural fields by incorporating the effects of surface roughness using multi-incidence angle ASAR data. Medium incidence angle (IS-4) with VV polarization of ASAR data had higher correlation coefficient to volumetric soil moisture content. The ratio of medium (IS-4) to high incidence (IS-6) angle could further reduce the effect of surface roughness. The effect of topography on the radar data is taken care by calculating local incidence angle derived from ASTER DEM data. The VV polarization in the sloping terrain provided better results in comparison to VH polarization. 相似文献
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通讯光缆选线的遥感及GIS辅助决策分析 总被引：1，自引：0，他引：1
详细介绍了基于遥感和地理信息系统(GIS)的某地通讯光缆选线基本流程。借助遥感和栅格GIS分析软件Idrisiforwindows,成功规划出了最佳通讯光缆支线位置,实现了通讯光缆选线的遥感和GIS辅助决策分析。 相似文献
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热红外遥感中大气下行辐射效应的一种近似计算与误差估计 总被引：12，自引：2，他引：10
在热红外遥感中,大气下行辐射效应很难处理,原因是地表双向反射分布函数很难精确描述。因此常见的处理方法是在如下２ 个假设前提下对该项作做简化计算： 一是假设地表反射为朗伯体特性,二是大气下行辐射在半球空间内取常数。该文提出了一种在地表为非朗伯体、大气下行辐射为非各向同性等一般条件下近似计算大气下行辐射效应的方法。通过数值模拟表明：（１） 所采用的方法可以在放弃２ 个假设的前提下,更精确地计算热红外大气下行辐射效应的数值,计算精度比２ 个假设前提下的计算方法至少提高２０ ．５３ ％ ;（２） 该方法所带来的误差是大气模式、遥感器视角和通道的函数。其中,通道４ 的相对误差比通道５大,同一通道中模式５ 的相对误差最大,但最大可能相对误差不到８ ％ ,且随扫描角的增大而减小;（３） 大气下行辐射效应项占总辐射亮度值之比例在±３０°视角范围内一般不超过４ ％ 。 相似文献