光学遥感影像的自动匀光处理及应用

针对光学遥感获取的影像存在一幅影像内部以及区域范围内多幅影像之间的色彩不平衡现象,提出了自动匀光处理方法和处理流程,通过影像匀光软件GeoDodging 4.0对原理和流程进行了实现,并结合实际工程应用取得了良好的效果。     

利用小波变换对影像进行融合的研究

基于小波变换可以对影像进行正交分解,而不丢失原来信号所包含的信息。提出了一种Wallis变换、小波变换和IHS变换相结合用于融合的方法,该方法可以有效地提高多光谱影像的空间分辨率,同时保持原来多光谱影像的色调。     

面向无缝影像数据库应用的一种新的光学遥感影像色彩平衡方法

 针对建立大型无缝影像数据库的影像数据特点，在深入分析与比较现有处理方法的基础上，基于Wallis变换，提出了一种改进的色彩平衡处理方法。该方法可以兼顾整体信息与局部信息，在处理大型无缝影像数据库色彩平衡问题时，既可以减小每张影像的处理误差，又可以消除处理误差的空间传递和积累问题，还便于辐射分辨率的保持。实验表明，该方法可以有效解决大型无缝影像数据库的色彩平衡问题。     

A combined image matching method for Chinese optical satellite imagery

Image matching is one of the key technologies for digital Earth. This paper presents a combined image matching method for Chinese satellite images. This method includes the following four steps: (1) a modified Wallis-type filter is proposed to determine parameters adaptively while avoiding over-enhancement; (2) a mismatch detection procedure based on a global-local strategy is introduced to remove outliers generated by the Scale-invariant feature transform algorithm, and geometric orientation with bundle block adjustment is employed to compensate for the systematic errors of the position and attitude observations; (3) we design a novel similarity measure (distance, angle and the Normalized Cross-Correlation similarities, DANCC) which considers geometric similarity and textural similarity; and (4) we introduce a hierarchical matching strategy to refine the matching result level by level. Four typical image pairs acquired from Mapping Satellite-1, ZY-1 02C, ZY-3 and GeoEye-1, respectively, are used for experimental analysis. A comparison with the two current main matching algorithms for satellite imagery confirms that the proposed method is capable of producing reliable and accurate matching results on different terrains from not only Chinese satellite images, but also foreign satellite images.     

Wallis 滤波在影像匹配中的应用

介绍了Wallis滤波器的基本原理和特性,将其应用于影像点特征提取和影像匹配,并列出了部分结果。     

Homogeneity testing: How homogeneous do heterogeneous cross-correlated regions seem?

The homogeneity of the flood frequency regime for a given pooling-group of sites is a fundamental assumption for many regional flood frequency analysis techniques. Assessing regional homogeneity is a critical step, which may be complicated by the presence of cross-correlation among flood sequences. The scientific literature proposes a number of statistical homogeneity tests and documents that inter-site correlation of floods is normally not negligible, but does not specifically address the impact of cross-correlation on such statistical tests. This paper analyzes the effectiveness of a well-known homogeneity test proposed in the scientific literature in the presence of inter-site cross-correlation through a series of Monte Carlo experiments. The numerical experiments enable us to comment on a possible theoretical correction for the test and to identify an empirical tool that accounts for the impact of inter-site cross-correlation of floods.     

正射影像上阴影区域检测与消除的方法

随着摄影测量和遥感技术的新发展,高分辨率正射影像的应用越来越广泛,而阴影现象则是这些航空影像中常见的问题之一。阴影的处理,主要包括阴影检测和阴影消除两部分。以色彩理论为基础,分析了航空影像中阴影的性质,总结了现有的阴影检测方法,并采用光谱比值法进行了阴影提取的实验;进而结合数字图像处理的相关算法,主要研究了基于改善Wallis滤波的阴影消除方法,通过相关试验表明,采用该算法得到了良好的视觉效果。     

超分辨率重建影像Wallis匀光拼接算法

由于计算机内存的限制,遥感影像的超分辨率重建一般采用分块算法进行处理,重建后的影像由于亮度、反差分布不均匀很难实现无缝拼接。针对超分辨率重建影像无重叠、规则大小的特点,本文提出了一种改进的加权Wallis匀光算法。该方法采用一种新的影像调整顺序,并使用加权法计算匀光参数,可以减少影像调整时误差的空间传递和累积,避免过度计算造成影像信息损失。最后,采用本文方法对900幅超分辨率重建后的资源三号影像进行匀光处理。试验结果表明：该方法能够使大幅面超分辨率重建影像达到亮度、反差一致性,取得了较好的匀光效果,达到了消除拼接缝的目的。     

相机检校中标志点的自动提取

本文针对相机检校中,手工选择标志点速度慢、强度大的缺点,提出了基于边缘提取和形状系数多级约束的方法。首先对图像进行Wallis滤波,并对滤波后的图像采用Canny算子进行边缘提取;然后在八邻域跟踪的基础上,根据边缘长度、边缘首末端点距离、形状系数和光谱信息检测符合条件的标志点边缘。通过实验验证,该方法可提取出92%左右的标志点。     

DMCⅢ航空数码影像匀光算法研究

DMCⅢ航空数码相机采用了新型的面阵CMOS传感器代替了原来的CCD传感器,导致影像亮度不平衡,严重影响了后期的空三加密工作。Wallis匀光算法主要用于多幅影像间的差异调整,能够有效地解决DMCⅢ影像的质量问题。本文详细地阐述了DMCⅢ影像的Wallis匀光算法,并结合实例进行验证,匀光效果理想。