共查询到20条相似文献，搜索用时 31 毫秒
1.
Two-Dimensional Spectrum Matched Filter Banks for High-Speed Spinning-Target Three-Dimensional ISAR Imaging 总被引：1，自引：0，他引：1
《Geoscience and Remote Sensing Letters, IEEE》2009,6(3):368-372
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Three-dimensional reconstruction of objects buried in layered media using Born and distorted Born iterative methods 总被引：6，自引：0，他引：6
Fenghua Li Qing Huo Liu Lin-Ping Song 《Geoscience and Remote Sensing Letters, IEEE》2004,1(2):107-111
We develop electromagnetic inverse scattering methods to reconstruct three-dimensional (3-D) objects buried in layered media. The nonlinear inverse problem is solved iteratively via the conjugate-gradient approach; within each iteration, the problem is linearized by Born and distorted Born approximations. The forward solution for layered media is provided by the stabilized biconjugate-gradient fast Fourier transform method. The inversion results from the Born and distorted Born iterative methods are presented, and the effects of the aperture size and noise on the inversion results are also investigated. Numerical results show that these methods are capable of reconstructing an arbitrary 3-D inhomogeneous object buried in a multilayered medium with high resolution. 相似文献
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Changzheng Ma Tat Soon Yeo Hwee Siang Tan Jun Wang Baixiao Chen 《Geoscience and Remote Sensing Letters, IEEE》2008,5(3):378-382
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永久散射体(PS)在非城区的分布密度通常难以满足PS-InSAR技术的地形监测需求,导致PS-InSAR监测误差较大,而非城区通常存在一定时段内的散射目标,即分时散射目标,为此,本文提出基于分时散射目标的改进PS-InSAR算法。首先采用通过边缘保持EMD算法对SAR影像干涉对进行降噪;然后以双层K-means聚类提取非城区的分时散射目标候选集,并通过可信概率提取可靠的分时散射目标;最后通过组内加权参数迭代和组间等权融合,计算监测区的地表形变。试验结果表明,提取的分时散射目标与同位置PS点具有相近的分布特性和变化趋势,较大地提高了非城区目标点的分布密度,提高了非城区地表形变监测的精度。 相似文献
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The three-dimensional ionospheric tomography (3DCIT) algorithm based on Global Navigation Satellite System (GNSS) observations have been developed into an effective tool for ionospheric monitoring in recent years. However, because the rays that come into or come out from the side of the inversion region cannot be used, the distribution of the rays in the edge and bottom part of the inversion region is scarce and the electron density cannot be effectively improved in the inversion process. We present a three-dimensional tomography algorithm with side rays (3DCIT-SR) applying the side rays to the inversion. The partial slant total electron content (STEC) of side rays in the inversion region is obtained based on the NeQuick2 model and GNSS-STEC. The simulation experiment results show that the algorithm can effectively improve the distribution of GNSS rays in the inversion region. Meanwhile, the iteration accuracy has also been significantly improved. After the same number of iterations, the iterative results of 3DCIT-SR are closer to the truth than 3DCIT, in particular, the inversion of the edge regions is improved noticeably. The GNSS data of the International GNSS Service (IGS) stations in Europe are used to perform real data experiments, and the inversion results show that the electron density profiles of 3DCIT-SR are closer to the ionosonde measurements. The accuracy improvement of 3DCIT-SR is up to 56.3% while the improvement is more obvious during the magnetic storm compared to the case of a calm ionospheric state . 相似文献
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《Geoscience and Remote Sensing Letters, IEEE》2008,5(4):630-634
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吕言 《武汉大学学报(信息科学版)》1988,(4)
本文提出一种既可用于从图象上提取具有某种用途的一维边缘,又可用于提取具有多种用途的二维边缘的序贯一维型边缘检测新算法。由于构成该算法重要组成部分的基础算子的作用,以及将二维问题化为一维问题求解而使其明显具有简单,快速、有效的特点。该算法还具有Abdou等所建议的边缘检测算子应具有的两个特性。 相似文献
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Hanjiang Xiong Wei Ma Jianya Gong Douadi Abdelalim 《International Journal of Digital Earth》2019,12(5):525-543
Realistic texture mapping and coherent up-to-date rendering is one of the most important issues in indoor 3-D modelling. However, existing texturing approaches are usually performed manually during the modelling process, and cannot accommodate changes in indoor environments occurring after the model was created, resulting in out-dated and misleading texture rendering. In this study, a structured learning-based texture mapping method is proposed for automatic mapping a single still photo from a mobile phone onto an already-constructed indoor 3-D model. The up-to-date texture is captured using a smart phone, and the indoor structural layout is extracted by incorporating per-pixel segmentation in the FCN algorithm and the line constraints into a structured learning algorithm. This enables real-time texture mapping according to parts of the model, based on the structural layout. Furthermore, the rough camera pose is estimated by pedestrian dead reckoning (PDR) and map information to determine where to map the texture. The experimental results presented in this paper demonstrate that our approach can achieve accurate fusion of 3-D triangular meshes with 2-D single images, achieving low-cost and automatic indoor texture updating. Based on this fusion approach, users can have a better experience in virtual indoor3-D applications. 相似文献
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基于地球物理反演算法,利用地表沉降信息快速获取油田储层状态信息,对于油田储层安全的实时监控具有重要意义。目前国内外对油田储层参数反演的研究相对较少,因此本文以典型的因石油开采引起地表沉降的辽河盘锦地区作为研究区域,以InSAR沉降监测结果作为观测数据,以Okada模型作为反演模型,首次将非线性贝叶斯反演算法引入到油田储层参数反演中。在试验过程中,发现油田地下存在不止一个油层,首次将双Okada模型引入到油田储层参数反演中。试验表明：①非线性贝叶斯反演算法不仅能够获取模型参数的最优值,同时可以对反演结果的不确定性做出解释。②与单源Okada模型相比,双Okada模型更符合该地区油田储层参数变化与地表沉降之间的映射关系,基于双Okada模型反演得到的油田储层参数更可靠。 相似文献
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A through-wall imaging problem for a 2-D scalar geometry is addressed. It is cast as an inverse scattering problem and tackled under the linear model of the electromagnetic scattering that is provided by the Born approximation. A truncated singular value decomposition inversion scheme is exploited, and the performances that are achievable by such an inversion scheme are assessed by exploiting synthetic data. The cases of weakly and strongly scattering objects are both considered. Finally, an example of reconstruction that is obtained by exploiting experimental data is presented. 相似文献
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An iterative method is presented which performs inversion of integrals defined over the sphere. The method is based on one-dimensional fast Fourier transform (1-D FFT) inversion and is implemented with the projected Landweber technique, which is used to solve constrained least-squares problems reducing the associated 1-D cyclic-convolution error. The results obtained are as precise as the direct matrix inversion approach, but with better computational efficiency. A case study uses the inversion of Hotine’s integral to obtain gravity disturbances from geoid undulations. Numerical convergence is also analyzed and comparisons with respect to the direct matrix inversion method using conjugate gradient (CG) iteration are presented. Like the CG method, the number of iterations needed to get the optimum (i.e., small) error decreases as the measurement noise increases. Nevertheless, for discrete data given over a whole parallel band, the method can be applied directly without implementing the projected Landweber method, since no cyclic convolution error exists. 相似文献
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Shiqi Huang Xinhua CaiShunxiang Chen Daizhi Liu 《International Journal of Applied Earth Observation and Geoinformation》2011
The interaction is quite complex between a ground object and an electromagnetic wave transmitted by synthetic aperture radar (SAR). In a ground resolution cell illuminated by a radar beam, there are many chaotic scatterers and the whole scattering echo has the chaotic characteristics which is usually described with the fractal theory, and the fractal dimension can be used to detect the change information for multitemporal SAR images. In order to improve the change detection effect with fractal model, this paper proposes a new multitemporal SAR image change detection algorithm based on the fractal model and wavelet transform (called FMWT algorithm). The FMWT algorithm has two advantages. One is insensitive to speckle noise; the other is that the change detection accuracy is improved, comparing with a general fractal change detection (GFCD) algorithm. Since the FMWT algorithm adopts the two-dimensional discrete stationary wavelet transform (TDDSWT) technique, it can obtain different direction sub-images and avoid down-sampling of the discrete wavelet transform (DWT). In the paper, not only the simulative data test has been carried out, but also the real natural disaster SAR images have been checked. Experimental results verify that the FMWT algorithm is feasible for multitemporal SAR image change detection, it is not sensitive to speckle noise of SAR images, and the performance of it is better than that of the GFCD algorithm. At the same time, the size of a sliding window will bring some affection in counting fractal dimensions. 相似文献
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SAR图像中散射目标的散射矩阵受极化方位角(POA)的影响会改变散射体的散射特性,散射矩阵是极化干涉SAR (PolInSAR)估计不同极化状态下复相干性的基础。本文根据极化方位角产生机制,建立了多视情况下基于极化方位角补偿的极化干涉相干性估计模型,分析了极化方位角补偿对相干性估计方法和不同散射机制下相干性估计的影响程度,研究了基于三阶段法与极化方位角补偿的植被参数反演。利用L波段SIRC全极化SAR图像为实验数据验证极化方位角补偿对极化干涉相干性估计和植被参数反演的可行性。实验结果表明,极化方位角补偿能够改变不同极化状态相干性分布规律,提高相干直线拟合精度,改善植被参数反演的可靠性和合理性。 相似文献
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在中场区通过对相位弯曲补偿进行微波成像,能大大降低对测试距离的要求,本文依据干涉逆合成孔径雷达成像(InSAR)原理,提出中场区滤波-逆投影三维成像算法,在获得目标散射点二维分布和强度信息的同时,还能得到其高度信息,实现中场区目标的三维成像。仿真和实验结果表明算法的有效性。 相似文献
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《International Journal of Digital Earth》2013,6(2):187-206
Abstract Multi-frequency C and L bands in the TOPSAR data have been utilized to reconstruct three-dimensional (3-D) bathymetry pattern. The main objective of this study is to utilize fuzzy arithmetic to reduce the errors arising from speckle in synthetic aperture radar (SAR) data when constructing ocean bathymetry from polarized SAR data. In doing so, two 3-D surface models, the Volterra algorithm and a fuzzy B-spline (FBS) algorithm, which construct a global topological structure between the data points, were used to support an approximation to the real surface. Volterra algorithm was used to express the non-linearity of TOPSAR data intensity gradient based on the action balance equation (ABC). In this context, a first-order kernel of Volterra algorithm was used to express ABC equation. The inverse of Volterra algorithm then performed to simulate 2-D current velocities from CVV and LHH band. Furthermore, the 2-D continuity equation then used to estimate the water depth. In order to reconstruct 3-D bathymetry pattern, the FBS has been performed to water depth information which was estimated from 2-D continuity equation. The best reconstruction of coastal bathymetry of the test site in Kuala Terengganu, Malaysia, was obtained with polarized L and C bands SAR acquired with HH and VV polarizations, respectively. With 10 m spatial resolution of TOPSAR data, bias of –0.004 m, the standard error mean of 0.023 m, r 2 value of 0.95, and 90% confidence intervals in depth determination was obtained with LHH band. 相似文献
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随着空间大地测量观测精度的提高,大地测量反演模型也更加精确细化,对反演算法也提出了更高的要求。针对球体分层位错模型断层参数反演问题,从反演参数的敏感性与相关性两个方面入手,分析了遗传算法在反演中的缺陷,提出了迭代最小二乘算法与遗传算法相结合的组合算法,利用模拟数据反演验证了算法的有效性。在遗传算法的断层参数反演中,断层的深度和滑距往往难以得到良好的结果,主要原因首先是上深度与下深度之间以及深度与滑距之间具有很强的相关性,其次是深度和滑距的敏感性相对来说也比较低。组合算法在各种倾角的断层上都取得了理想的反演结果,具有实用性。 相似文献
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M. E. O’Kelly 《Journal of Geographical Systems》2009,11(3):227-241
The minimax hub location problem sites a facility to minimize the maximum weighted interaction cost between pairs of fixed nodes. In this paper, distances are represented by a rectilinear norm and may be suited to factory layout or street
network problems. The problem is already well known (in 2-D) as the round trip location problem and is extended to 3-D in
this paper. One rationale for the solution method is based on an extension of the geometric arguments used to solve the minimax
single facility location problem. Suppose a budget is provided for interactions, and that each interaction must be accomplished
for no more than this cost. The algorithm uses a bi-section search for the feasible budget until it finds the expenditure
needed to provide for these flows. The extension in the present paper is that the nodes are permitted to be on different layers
(levels). This 3-D version of the problem appears to be a new variant of the hub model. The models and solution techniques
developed in the paper are illustrated using a small 55 node problem. Because of a relatively efficient implementation of
the bi-section search, the algorithm in 2-D and 3-D is also applied successfully to a 550 node problem.
相似文献
| M. E. O’KellyEmail: |
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Li Qingquan 《地球空间信息科学学报》2013,16(1):11-16
The Tetrahedral Network(TEN) is a powerful 3-D vector structure in GIS, which has a lot of advantages such as simple structure, fast topological relation processing and rapid visualization. The difficulty of TEN application is automatic creating data structure. Although a raster algorithm has been introduced by some authors, the problems in accuracy, memory requirement, speed and integrity are still existent. In this paper, the raster algorithm is completed and a vector algorithm is presented after a 3-D data model and structure of TEN have been introducted. Finally, experiment, conclusion and future work are discussed. 相似文献