基于不同小波变换与同态滤波结合的CBERS-02B卫星CCD图像的薄云去除

卫星CCD图像的去云处理对遥感信息的增强与提取有重要的意义,尤其是在云覆盖严重的低纬度地区。为去除CBERS-02B卫星CCD图像中薄云的影响,分别使用Mallat和à trous 2种小波变换对图像进行分解;利用同态滤波对2种小波分解图像的低频系数进行处理,衰减其低频信息;将处理后的小波低频系数与分解的高频系数进行小波重构,从而达到去云的目的。定量分析基于Mallat和à trous小波变换结合同态滤波法的去云结果表明,经à trous小波变换结合同态滤波法的去云影像所包含信息量大,细节信息丰富,去云效果较好。     

基于移不变全方向角提升的遥感图像降噪

在分析遥感图像结构特征及其与噪声之间主要区别的基础上,利用图像信号的方向信息,提出基于移不变全方向角提升小波（TI—OL）抑制遥感图像噪声的方法。该方法在方向提升小波变换的基础上并利用循环平移,Gabor小波滤波器和图像旋转技术改进了方向提升小波在图像去噪过程中存在的三个弊端：缺乏移不变性质,图像局部方向信息判方法断缺乏噪声鲁棒性和变换方向分布有限。消除去噪结果中的吉布斯效应,提高图像方向信息判断的准确性并保证图像纹理方向始终落在方向提升能最优表示的方向区间内。试验结果证明所提方法在处理遥感图像的过程中能在去噪的同时保留图像的细节和边缘信息,对遥感图像中的边缘信息如道路和桥梁有较好的刻画性能,较传统方法去噪性能（PSNR）和主观视觉效果（SSIM）均有较大提高。     

LIDAR点云滤波算法分析——以ISPRS测试实验为参考

在分析ISPRS测试实验的基础上,研究机载LIDAR点云数据滤波算法的特性,将算法分成4类进行介绍,总结经典算法的定量分析性能,为后续的研究提供一个参考,并展望滤波算法改进和发展的方向.     

卡尔曼滤波算法的灰色理论模型在变形监测中的应用

本文针对灰色理论模型在建模过程中受到随机扰动影响这一问题,提出了利用卡尔曼滤波处理建模数据的方法.经过实例检验,证明基于滤波算法的灰色理论模型在一定程度上可以提高预测值的精度,更好地反映了观测目标的变形趋势,在变形监测中具有一定的优势.     

抗差自适应卡尔曼滤波在GPS精密单点定位中的应用

卡尔曼滤波是GPS精密单点定位中最常用的参数估计方法.理论上讲,随着观测数据的增多,通过卡尔曼滤波可以得到更精确的状态估值,但有时由于状态异常或发生大的周跳等原因,使得状态估值与实际状态之间的误差较大,滤波会发生发散现象,为此,本文提出了将抗差自适应滤波模型运用到精密单点定位中,通过算例分析显示,该方法将显著提高定位结...     

InSAR干涉图的高斯加权圆周期滤波

本文在阐述与分析传统圆周期滤波方法--圆周期中值滤波的基础上,结合高斯函数,提出了高斯加权圆周期滤波算法,用真实的SAR干涉图数据实验,证明了该方法具有较好的滤波效果.     

基于"当前"统计模型的载体速度计算

本文通过分析描述载体运动的"当前"统计模型,设计了基于"当前"统计模型计算载体速度的自适应卡尔曼滤波算法.利用航空飞行实验中获得的相位观测值,进行时序差分得出相位率,并对其组双差,获得计算速度的双差多普勒频移值,使用设计的算法进行计算分析,同时与常加速度模型的滤波结果做了比较.结果表明在静态和动态情况下,"当前"统计模...     

A bundle adjustment approach with inner constraints for the scaled orthographic projection

Bundle adjustment is a method for simultaneously calculating both the interior and exterior orientation parameters of a set of images, and the object-space coordinates of the observed points. In the case of long focal length lenses and narrow field-of-view (FOV) imaging situations, collinearity based (perspective projection) algorithms may result in linear dependencies between parameters that cause solution instability. The use of a scaled orthographic projection model based on linear algebraic formulations was therefore adopted to reduce this risk. Using quaternions, a new mathematical model is derived that includes the partial derivatives as well as the inner constraint equations for a scaled orthographic bundle adjustment. The model was then tested using two image sets of a single, small vessel (about 6 m length) with a cube target of known dimensions at two distinct ranges; perspective solutions were also calculated for comparison. RMS residual errors of 0.74-0.78 pixels associated with the new method compare favorably to a residual error range of 0.59-0.74 pixels using a perspective bundle adjustment of the same target points. Relative precisions (as a ratio of target size) of between 1:1650 and 1:750 have been achieved at ranges of 375 m and 850 m, respectively, given comparisons with the known cube dimensions. A third image dataset consisting of a network of 16 images was solved with a 1:2200 relative precision showing the new method can successfully handle high redundancy. For the experiments that were conducted, the new method was found to produce less precise results than the perspective bundle solution for a FOV of 0.50-0.65° where the object fills 5-8% of the image. However, it was found to match the precision of the perspective model (with an uncalibrated camera) for a FOV of 0.20-0.30° where the object of interest fills only 1-2% of the full image.     

Broadband Analytical Solution to the Scattering of Plane SV Waves by Circular Cylindrical Canyons

Based on Fourier-Bessel series expansion of wave functions,an analytical solution to 2-D scattering ofincident plane SV waves by circular cylindrical canyons with variable depthto-width ratios is deduced in this paper. Unlike other analytical solutions,this paper uses the asymptotic behavior of the cylindrical function to directly define the undetermined coefficients of scattered waves,thus,avoiding solving linear equation systems and the related numerical computation problems under high-frequency incident waves,thereby broadening the applicable frequency range of analytical solutions. Through comparison with existing analytical solutions,the correctness of this solution is demonstrated. Finally, the incident plane SV wave scattering effect under circular cylindrical canyons in wider frequency bands is explored.     

速度传感反馈地震计的参数稳定性分析

从理论上定量分析机械摆和环路滤波等开环诸参数变化对速度传感反馈地震计闭环参数的影响.研究指出,在环路设计中可半自由选取的开环阻尼取值对参数稳定性有重要影响.过大或过小的开环阻尼取值均可能造成参数稳定性急剧变差,影响地震计在只标不调的状况下长期连续稳定工作.