基于商空间粒度的极化SAR图像分类

当前极化合成孔径雷达(SAR)图像的分类研究中,极化信息的不完全利用是影响极化SAR图像分类效果的重要原因之一。故将商空间粒度合成理论引入到极化SAR图像分类中,通过建立不同的支持向量机(SVM)分类器构建不同的商空间,从多个粒度层面实现对极化信息的综合利用。首先通过不同的极化分解方法得到不同的极化特征,分别对其建立不同的支持向量机分类器进行分类;再根据粒度合成理论对这些商空间进行融合,得到更细粒度上的改进的分类结果。最后,利用AIRSAR图像进行实验比较,算法改进后的结果在地物误分上有明显的抑制,各类别分类正确率都有所提高。     

图像分割的商空间粒度原理

从商空间粒度理论角度分析图像分割概念,研究已有的图像分割方法,提出图像分割的商空间粒度原理．用商空间的三元组（X,f,Г）-（[X],[f],[Г]）来描述图像分割过程,阐述基于商空间粒度计算理论的图像分割原理及基于粒度分层、合成及其综合技术下图像分割的方法,并提出了基于粒度合成原理的复杂纹理图像的分割算法．该算法通过分别提取多纹理图像中纹理区域的方向性及粗细度特征,形成图像的不同粒度,然后根据粒度合成原则,对所形成的粒度进行合成,从而实现对纹理图像的分割,实验表明该算法对复杂纹理图像分割是有效的．     

基于商空间粒度计算的图像检索

在图像检索领域应用商空间粒度思想,阐述了图像检索中的粒度原理,对图像检索问题进行商空间描述,并构造等价关系,提出了一种新的图像检索方法.根据图像在不同粒度下的表现构造不同粒度下的商空间,然后根据商空间粒度合成原理构造最优准则函数,对已得到的商空间进行属性合成,进而以合成后的属性函数来完成图像检索.与采用单一属性特征的图像检索方法相比,该方法能够在更大程度上利用图像自身所提供的信息,取得更好的检索效果和更高的查全率查准率指标.     

基于多通道分类合成的SAR图像分类研究

SAR具有全天时、全天候工作能力,且能够提供高分辨率图像数据。SAR图像分类是SAR图像处理的关键步骤。目前,SAR图像分类多是基于单通道图像数据。多通道SAR数据极大地丰富了地物目标信息量,利用多通道数据进行分类,是SAR图像分类的重要发展方向。本文提出基于多通道分类合成的SAR图像分类算法。该算法首先利用SVM对不同通道的数据分别进行分类,然后利用粒度合成理论对不同的分类结果进行合并,最后实现多通道SAR数据图像分类。本文重点论述了利用该方法进行SAR图像分类的基本流程和步骤。最后,结合实验结果,证明了该算法的可行性和有效性。     

基于粒度计算的覆盖算法

为了更好地解决高维海量数据的分类问题,本文提出一种基于粒度计算的覆盖算法.该算法以粒度计算为理论依据,指出在分析研究某一问题时,可以适当将其属性、论域或者结构粗化,求得某个商空间,在该商空间中抓住事物的本质对其研究,对某些在同一个粗粒度世界无法识别或者彼此特征区别很弱的对象可以换一个粒度世界对其分析,从而全面了解整个问题;以构造性学习算法--覆盖算法为具体实现工具,得到多个商空间中的结果,最终由商空间理论中的函数合成法获得完整结果.实验证明这种基于粒度计算的覆盖算法在解决分类问题时是行之有效的.     

图像滤波的商空间粒计算算法

针对传统滤波器在噪声检测和滤除中存在的不足,提出了基于商空间粒度理论的噪声检测和粒度逆谐波均值滤波算法。该算法将受噪声污染的图像划分成不同粒度层次的商空间,形成商空间半序格,结合保假原理选择适当的粒度空间实施噪声分类检测和分别滤除。实验结果表明,该算法在滤除噪声的同时能够较好地保持图像的细节纹理特征、改善图像质量、提高信噪比等。     

多粒度的图像检索方法研究

从商空间粒度理论角度分析了图像检索的过程,给出了基于商空间的多粒度图像检索方法。首先根据等价关系R(即图像主色的连通性)将图像划分为不同的区域,然后分别从颜色、形状、空间分布等不同的粒度提取区域的特征属性,利用商空间多粒度属性函数合成思想,将每个粒度下的属性函数合成,形成图像的特征向量,再根据此特征向量计算图像之间的相似度进行检索。实验结果表明,多粒度属性函数合成的检索方法要明显优于单一属性函数下的检索方法;与MTH方法和颜色体积直方图方法相比,其能够更加准确和高效地查找出用户所需要内容的图像,明显地提高了检索精度。     

作物产量预测的粒度分析法

针对作物产量预测,提出基于商空间粒度计算的分析法。在商空间粒度计算理论思想下,分析作物产量序列中粒度的选取,用属性划分方法对论域X进行颗粒化,对属性f取不同的粒度进行颗粒化。通过属性的粒度变化对论域进行划分,得到新的商空间并应用其解决问题,可以降低问题复杂度。通过商空间理论中的分层与合成技术选取大小合适的粒度,能全面获取产量序列中的信息,也更加符合人类智能特点。冬小麦产量预测实验结果也证明这种粒度分析和选取方法是有效的。     

基于商空间的向量空间模型文本分类方法

为了降低基于向量空间模型(VSM)的文本分类方法的向量维数,并减少噪声对分类的影响,现利用商空间的粒度理论对基于VSM的分类模型进行改进,提出了一种基于商空间的新的VSM分类方法,该方法降低了基于VSM文本分类的向量维数,提高了不同文本之间的辨别能力.     

基于商空间粒度理论的三维网格分割方法

通过研究已有的网格分割和模型简化方法 ,分析三维模型的网格分割中的商空间粒度思想 ,并将商空间粒度计算引入到网格分割中 ,对网格分割过程进行描述 ,提出了基于粒度分层合成技术的网格分割方法。该算法通过分别提取模型中各三角形网格区域的几何特征构成不同的粒度区域 ,再根据粒度合成理论。将这些所形成的粒度组织起来 ,从而实现对三维网格的最终分割 ,为三角网格模型的简化提供了快速有效的方法。实验表明了该算法对于网格分割的有效性和正确性。     

.基于纹理和边缘的SAR图像SVM分类*

为实现SAR图像地物目标的有效分类,深入研究了基于灰度共生矩阵GLCM的四种纹理特征以及两个边缘特征。分析每个单独纹理或边缘特征在对SAR图像进行支持向量机SVM分类中对不同地物的分辨能力,选取不同的特征组合进行组合特征的SVM分类实验。对各种特征进行主成分分析PCA,并考察使用和不使用PCA两种情况下分类结果之间的差异。实验结果证明能量、边缘长度、对比度和相关度的特征组合在PCA作用下能够改善各类地物的分类精度,将总分类精度提高到90%以上。     

Performance analysis of textural features for characterization and classification of SAR images

A new method has been presented to compare the performance of textural features for characterization and classification of SAR (Synthetic Aperture Radar) images. In contrast to the conventional comparative studies based on classification accuracy, this method emphasizes the sensitivity of texture measures for grey level transformation and multiplicative noise of different speckle levels. Texture features based on grey level run length, texture spectrum, power spectrum, fractal dimension and co-occurrence have been considered. A number of image samples of built-up, barren land, orchard and sand regions were considered for the study. The interpretation of the results is expected to provide useful information for the remote sensing community, which employs textural features for segmentation and classification of satellite images.     

Block-regression based fusion of optical and SAR imagery for feature enhancement

This paper focuses on the establishment of a pixel-level fusion framework for optical and synthetic aperture radar (SAR) images to combine these two types of remotely sensed imagery for feature enhancement. We have proposed a new fusion technique, namely block-based synthetic variable ratio (Block-SVR), which is a technique based on multiple linear regression of block regions to fuse optical and SAR imagery. In order to investigate the effectiveness of the method, the fusion results of a higher resolution airborne SAR image and a lower resolution multispectral image are presented. According to the fusion results, the fused images have enhanced certain features, namely the spatial and textural content and features that are invisible in multispectral images, while preserving colour characteristics. The spectral, spatial and textural effects of the presented algorithm were also evaluated mainly by visual and quantitative methods, and compared to those of intensity-hue-saturation (IHS), principal component analysis (PCA) and wavelet-based methods. During the implementation of the block-regression based technique there are at least two advantages. One is that the block-regression based technique drastically decreases the amount of computation, whereas regression of the whole scene image is almost impossible. The other, most important, advantage is that adjustment of regressed block size can result in different emphasis between preservation of spectral characteristics and enhancement of spatial and textural content. The larger the regression block, the more the spatial and textural details are enhanced. In contrast, the smaller the regression block, the more the spectral features are preserved. The assessments indicate that the block-regression based method is more flexible than others, because it can achieve a satisfactory trade-off between preservation of spectral characteristics and enhancement of spatial and textural content by selection of optimal block size with respect to visual interpretation and mapping. This paper also proposes a scheme for the fusion of SPOT5 panchromatic, XS images with airborne SAR images using the block-regression based technique.     

基于KNN的特征自适应加权自然图像分类研究

针对自然图像类型广泛、结构复杂、分类精度不高的实际问题, 提出了一种为自然图像不同特征自动加权值的K-近邻（K-nearest neighbors, KNN）分类方法。通过分析自然图像的不同特征对于分类结果的影响, 采用基因遗传算法求得一组最优分类权值向量解, 利用该最优权值对自然图像纹理和颜色两个特征分别进行加权, 最后用自适应加权K-近邻算法实现对自然图像的分类。实验结果表明, 在用户给定分类精度需求和低时间复杂度的约束下, 算法能快速、高精度地进行自然图像分类。提出的自适应加权K-近邻分类方法对于门类繁多的自然图像具有普遍适用性, 可以有效地提高自然图像的分类性能。     

基于粒计算的空间特征提取及其检索的研究

利用四叉树算法将图像分割成若干子块,根据子块的颜色直方图,将提取图像的空间特征与提取图像的颜色特征结合起来,然后运用粒计算理论对提取的图像空间特征进行粒化,得到特征向量,并对其进行归一化。在此基础上,结合相关反馈机制设计基于粒计算的融合多特征的人机交互式图像检索的综合算法,该算法的复杂度低,能够在很大程度上提高图像检索的效率和准确性。     

A novel algorithm for land use and land cover classification using RADARSAT-2 polarimetric SAR data

This study proposes a new four-component algorithm for land use and land cover (LULC) classification using RADARSAT-2 polarimetric SAR (PolSAR) data. These four components are polarimetric decomposition, PolSAR interferometry, object-oriented image analysis, and decision tree algorithms. First, polarimetric decomposition can be used to support the classification of PolSAR data. It is aimed at extracting polarimetric parameters related to the physical scattering mechanisms of the observed objects. Second, PolSAR interferometry is used to extract polarimetric interferometric information to support LULC classification. Third, the main purposes of object-oriented image analysis are delineating image objects, as well as extracting various textural and spatial features from image objects to improve classification accuracy. Finally, a decision tree algorithm provides an efficient way to select features and implement classification. A comparison between the proposed method and the Wishart supervised classification which is based on the coherency matrix was made to test the performance of the proposed method. The overall accuracy of the proposed method was 86.64%, whereas that of the Wishart supervised classification was 69.66%. The kappa value of the proposed method was 0.84, much higher than that of the Wishart supervised classification, which exhibited a kappa value of 0.65. The results indicate that the proposed method exhibits much better performance than the Wishart supervised classification for LULC classification. Further investigation was carried out on the respective contribution of the four components to LULC classification using RADARSAT-2 PolSAR data, and it indicates that all the four components have important contribution to the classification. Polarimetric information has significant implications for identifying different vegetation types and distinguishing between vegetation and urban/built-up. The polarimetric interferometric information extracted from repeat-pass RADARSAT-2 images is important in reducing the confusion between urban/built-up and vegetation and that between barren/sparsely vegetated land and vegetation. Object-oriented image analysis is very helpful in reducing the effect of speckle in PolSAR images by implementing classification based on image objects, and the textural information extracted from image objects is helpful in distinguishing between water and lawn. The decision tree algorithm can achieve higher classification accuracy than the nearest neighbor classification implemented using Definiens Developer 7.0, and the accuracy of the decision tree algorithm is similar with that of the support vector classification which is implemented based on the features selected using genetic algorithms. Compared with the nearest neighbor and support vector classification, the decision tree algorithm is more efficient to select features and implement classification. Furthermore, the decision tree algorithm can provide clear classification rules that can be easily interpreted based on the physical meaning of the features used in the classification. This can provide physical insight for LULC classification using PolSAR data.