Monitoring of slow ground deformation by ERS radar interferometry on the Vauvert salt mine (France): Comparison with ground-based measurement

The differential SAR Interferometry (DInSAR) technique has been applied to a test site near Vauvert (France) to detect and monitor ground deformation. This site corresponds to the location of an industrial exploitation of underground salt using the solution mining technique. An area of subsidence has been observed using in situ measurements. Despite conditions unfavorable for InSAR because of the vegetal cover, we show that radar remote sensing observations provide valuable information which substantially improves our knowledge of the phenomenon. An adaptive phase filtering process has been used to improve the coherence level. In particular, our study shows that the geometry of the subsidence bowl is different to that previously assumed using ground-based techniques only. The size of the subsidence bowl (8 km) is larger than expected. This information will be useful for further modeling of the deformation and to improve the coverage of the in situ measurement networks. It also shows that radar interferometry can be used for the long-term monitoring of such sites and to predict potential environmental issues.     

基于图像块能量梯度的多聚焦图像融合

针对多聚焦图像,提出一种基于图像分块的融合方法。将源图像分为大小相同数量相等的子块,采用能量梯度算子作为对焦评价函数,计算各个图像子块能量梯度匹配度,设置匹配度阈值分离出源图像中的清晰区域。源图像中的清晰区域直接作为融合图像相应的区域,其它区域的处理中,构造与相应子块能量梯度大小相关的图像序列,以及像素点到各个子块中心距离相关的融合函数,然后用融合函数对图像序列融合。实验结果表明该方法有效性和合理性。     

Sparse synthetic aperture radar imaging with optimized azimuthal aperture

To counter the problem of acquiring and processing huge amounts of data for synthetic aperture radar(SAR)using traditional sampling techniques,a method for sparse SAR imaging with an optimized azimuthal aperture is presented.The equivalence of an azimuthal match filter and synthetic array beamforming is shown so that optimization of the azimuthal sparse aperture can be converted to optimization of synthetic array beamforming.The azimuthal sparse aperture,which is composed of a middle aperture and symmetrical bilateral apertures,can be obtained by optimization algorithms(density weighting and simulated annealing algorithms,respectively).Furthermore,sparse imaging of spectrum analysis SAR based on the optimized sparse aperture is achieved by padding zeros at null samplings and using a non-uniform Taylor window.Compared with traditional sampling,this method has the advantages of reducing the amount of sampling and alleviating the computational burden with acceptable image quality.Unlike periodic sparse sampling,the proposed method exhibits no image ghosts.The results obtained from airborne measurements demonstrate the effectiveness and superiority of the proposed method.     

关于Photoshop插件的SAR图像处理探究

SAR图像处理主要包括相干斑抑制、特征提取等,如果在使用Photoshop插件SAR图像处理图片,将主要精力集中于算法的设计和优化方面,可以尽量减少在用户界面、内存管理和基本的图像操作方面的编程,既可以实现多种图像处理,又容易实现功能的充分扩大与填充,从而在最短的时间内做做多的事。     

海底油渗SAR探测综述

海底油渗来源于海底石油的自然渗漏，及时地获得海底油渗信息对探测、开发海底石油资源具有重大意义。目前，合成孔径雷达（Synthetic Aperture Radar, SAR）已经成为海底油渗探测的新型辅助手段。首先总结了海底油渗SAR探测机理，包括海底油渗形成机制、海底油渗SAR成像原理和海底油渗SAR图像特征;其次介绍了海底油渗SAR探测方法;然后给出了目前国际上海底油渗SAR探测的应用现状;最后提出了海底油渗SAR探测的现存问题和未来发展方向。     

A New Method for Encrypting Images with Few Details Using Rijndael and RC6 Block Ciphers in the Electronic Code Book Mode

ABSTRACT

In this paper, we propose an efficient method for encrypting images with few details using Rijndael and RC6 block ciphers in Electronic Code Book (ECB) mode. Images with few details are images with large areas of similar gray levels such as medical images, infrared images, and logo images. This leads to encryption leakage if the Rijndael or RC6 block ciphers are used. The proposed method solves this problem by using a preprocessing step to eliminate the repeated patterns before encryption. A comparison is held between encryption of images with few details with preprocessing and encryption without preprocessing. Experimental results verify that the proposed preprocessing method gives the encryption algorithms the ability to encrypt images with few details in an efficient manner in the ECB mode.     

EMT中传感器位置偏差对成像结果的影响

以电磁层析成像(EMT)仿真系统为研究对象,讨论了检测线圈位置偏移和角度偏转对成像结果的影响。利用相对误差平均值、相对误差最大值和相对误差最小值等作为评价指标,比较了在二维空间上检测线圈各个轴向上位移偏差和角度偏转造成的检测值误差,给出了图像重建结果,得出结论:当测量数据存在噪声时,重建的图像位置会接近物场的边缘,即离近线圈传感器,对于校正传感器模型有实际意义。     

一种综合的SAR图像边缘检测方法

针对合成孔径雷达图像中斑点噪声的特性,基于中值滤波方法,并结合Ratio算子、Canny算子和双阈值连接三种处理方法,提出一种综合的边缘检测算法。实验结果表明,与传统算法比较,该算法克服了边缘方向量化带来的直线断裂,边缘定位准确,显著提高了边缘检测正确率,并对噪声有抑制作用,从而取得了良好的检测效果。