基于DWT的天宫二号三维成像雷达高度计陆表水体图像融合研究  

A DWT-based Fusion of Inland Water Images Acquired by Tiangong-2 Interferometric Imaging Radar Altimeter

作　　者：程玉 张云华 李东 董晓 石晓进 杨杰芳 康雪艳 翟文帅 CHENG Yu;ZHANG Yunhua;LI Dong;DONG Xiao;SHI Xiaojin;YANG Jiefang;KANG Xueyan;ZHAI Wenshuai(CAS Key Laboratory of Microwave Remote Sensing,National Space Science Center,Chinese Academy Sciences,Beijing 100190,China;University of Chinese Academy of Science,Beijing 100049,China)

机构地区：[1]中国科学院国家空间科学中心中国科学院微波遥感技术重点实验室,北京100190 [2]中国科学院大学,北京100049

出　　处：《遥感技术与应用》2024年第3期579-589,共11页Remote Sensing Technology and Application

基　　金：国家自然科学基金面上项目(61971402)。

摘　　要：陆表水体是人类赖以生存的重要资源。天宫二号三维成像雷达高度计(TG2-InIRA)在国际上首次采用小入射角、短基线雷达干涉测量技术获取地球海洋和陆表水体的准镜面反射信息,克服了传统星载雷达高度计和星载合成孔径雷达不能获取宽刈幅水体高度的不足。然而在小入射角情况下水体散射易受观测角度变化的影响,且水体在不同气象条件下表面粗糙度的变化容易导致雷达影像呈现较大差异,因此开展多角度、多时相TG2-InIRA水体图像融合对于全面了解陆表水体真实状态十分重要。研究提出了一种基于离散小波变换(Discrete Wavelet Transform,DWT)的TG2-InIRA雷达图像融合方法,DWT旨在将待融合雷达图像分解为低频子图像和高频子图像。陆表水体在形态学上呈现出极大的多样性,这些在频域表现为丰富的低频和高频特征,对其融合需采用不同的策略。具体地,低频方面,提出了一种基于Canny算子的融合规则,突出江河、湖泊等大型水体宏观特征;高频方面,发展出了一种基于局部对比度的融合规则,突出细小水体及水体边缘等微观特征。在长江流域安庆地区多角度、多时相TG2-InIRA雷达图像上与加权平均以及基于Laplacian金字塔、Nonsubsampled Contourlet变换和DWT的几种常用经典融合方法所做的对比实验表明,所提方法在清晰度、交叉熵等评价指标上均有明显提升,基于融合结果所开展的图像分割实验进一步展示了所提方法在提取水体的精细度和完整性方面的良好性能。Inland water is an important resource for human beings.Tiangong-2 Interferometric Imaging Radar Altimeter(TG2-InIRA)is the first spaceborne radar altimeter which adopts the short-baseline interferometry to measure the digital elevation model of oceans and inland waters on Earth with wide swath.It is also the first spaceborne imaging radar which takes an obviously small incidence to acquire the strong quasi-specular scatter⁃ing of earth water.Nevertheless,the scattering of water is easily affected by observation angles and changes over time under different weather conditions,it is thus necessary to fuse the TG2-InIRA images of multi-angle and multi-temporal for a comprehensive sensing of the real state of inland water.Therefore,a Discrete Wavelet Transform(DWT)-based fusion of inland water images acquired by TG2-InIRA is proposed,where the DWT is used to decompose the to be fused source images into two components of low frequency and high frequency.Different fusion rules should be designed for these two components in view of the fact that the morphology of in⁃land water shows great diversity in frequency domain.Specifically,a Canny operator-based fusion rule is pro⁃posed for the low-frequency components so as to highlight the global features of large water bodies such as riv⁃ers and lakes.A contrast enhancement-based fusion rule is developed for the high-frequency components so as to refine the local features such as small water bodies and water edges.Comparative experiments on two multiangle and multi-temporal TG2-InIRA images in Anqing area with five widely-used fusion methods including the weighted averaging,the Laplace pyramid-based fusion,the non-subsampled contourlet transform-based fu⁃sion and two other DWT-based fusions demonstrate the obviously improved performance on quantitative index⁃es such as clarity,standard deviation,mean square error and cross-entropy.The image segmentation experi⁃ment based on the fused images further shows the nice fineness and integrity performance of the proposed

关 键 词：陆表水体 图像融合 三维成像雷达高度计 离散小波变换 雷达图像处理 

分 类 号：TP751[自动化与计算机技术—检测技术与自动化装置] TP79[自动化与计算机技术—控制科学与工程]