融合嫦娥一号CCD影像与DEM数据的月球撞击坑自动提取和识别

针对现阶段月球撞击坑定量信息提取不足和误提取的问题,本文提出了一种融合CCD影像和DEM数据进行撞击坑的自动提取及识别的算法。（1）在太阳光照下,撞击坑的影像特征满足特定的规律,通过条件匹配在CCD影像中提取撞击坑;（2）在DEM中,利用撞击坑坑壁点的坡向值的连续性,对影像中误提取的撞击坑进行剔除;（3）在DEM中,利用撞击坑边缘点法向量的突变性,提取撞击坑边缘点并进行拟合,计算撞击坑的参数,通过坑底点云所占比例以及剖面线特征识别撞击坑的类型。经过“嫦娥一号”影像与DEM数据的验证,该算法在高纬度月球撞击坑分布均匀的区域应用效果较好。     

基于嫦娥一号CCD数据空间特征的特定目标识别

基于嫦娥一号CCD数据的空间特征,开展月球表面陨石坑和线性构造目标识别的探索研究。利用图像边缘检测算法将影像分割成许多目标体;为了解决过度分割和错分问题,根据分割结果对分割后的目标体进行合并;为获取地质意义和语义信息更丰富的陨石坑和线性构造目标,将合并结果导入ArcGIS进行手动修改。最后,以影像数据的空间特征为基础,基于规则分类原理,根据研究需要设定不同的识别规则,进行陨石坑和线性构造的自动识别,取得了较好的效果。     

几何约束条件下的SIFT倾斜影像匹配

针对倾斜摄影包含多个视角的影像因而使不同视角之间的影像具有较大的仿射畸变的问题,提出了一种基于几何约束和SIFT的倾斜影像匹配算法。首先根据POS值对所有的倾斜影像进行畸变校正,然后利用SIFT GPU对所有影像进行匹配。对于整个测区的影像,首先根据POS值获取影像间的拓扑关系,其次是影像之间的两两匹配,最终完成特征点追踪,生成光束法平差所需的同名点对。试验结果表明,该算法在效率、精度及匹配点数量上都可以很好地满足后续的光束法平差。     

月球撞击坑分类检测研究

根据嫦娥二号采集的月球CCD影像,基于分类检测的方法,对撞击坑进行识别检测研究。针对简单撞击坑、撞击盆地和复杂撞击坑的不同形态特征和影像特征,采用不同的滤波和检测算子进行识别。结果表明,对直径在1.5 km以上且光照条件较好的简单撞击坑和撞击盆地识别效果较好;对于复杂撞击坑,由于其形态结构相对复杂,造成图像边缘特征不突出,因此识别率相对较低,有待进一步改进。     

杭州湾HJ CCD影像悬浮泥沙遥感定量反演

利用环境小卫星CCD(HJ CCD)影像对杭州湾悬浮泥沙浓度(SSC)进行了反演研究。通过对杭州湾水体遥感反射率(Rrs)与SSC进行相关性分析发现,在690nm和830nm左右出现显著的反射峰,分别位于HJ CCD影像的第3和第4波段范围内;大于700nm波长处的Rrs与SSC相关性较好。基于实测Rrs和SSC之间的相关关系,利用第4和第3波段比值作为遥感因子建立SSC反演模型,模型决定系数达到0.90。借鉴近红外-短波红外(NIR-SWIR)结合的大气校正方法反演出的准同步MODIS气溶胶数据,实现了HJ CCD影像的大气校正,第3、第4波段的大气校正结果相对误差分别为5.54%和6.97%。结果显示,HJ CCD影像反演的SSC相对误差为7.12%;杭州湾悬浮泥沙浓度要显著高于长江口,且内部差异明显。研究表明,通过适当的大气校正方法和反演算法,HJ CCD影像可用于杭州湾悬浮泥沙浓度的估计。     

MODIS和HJ-1 CCD数据时空融合重构NDVI时间序列

遥感数据反演高时空分辨率NDVI对监测植被动态变化过程具有重要意义,然而受天气影响,单颗卫星难以提供时间连续的高空间分辨率NDVI数据。以华北平原中东部为实验区,联合HJ-1 CCD数据和MODIS数据,对STARFM算法进行了改进,(1)考虑了不同地物对光谱响应的差异,为减少分类错误利用统计学上()对分类数据进行筛选,按照不同地物类型分别利用线性拟合方法修改光谱距离权重;(2)定义了预测半径,对HJ-1 CCD数据因外界影响而缺失的影像进行了预测。结果表明,与真实影像相比,预测结果呈现了较好的空间一致性,相关系数均达到了极显著相关,改进算法的预测精度要高于原算法。利用该方法将HJ-1 CCD NDVI的空间变化信息与MODIS NDVI时间变化信息有机结合重构了高时空分辨率NDVI序列,有效补充了HJ-1CCD NDVI的缺失数据集。     

基于特征的影像匹配算法性能评估

目前,针对影像特征匹配的算法有很多,但是对于不同地物特征的影像,无法准确地选取可适用的匹配算法。针对此问题,本文选取了四种稳健的算法SIFT、SURF、ORB、AKAZE,在四种不同地物特征的相似影像上进行特征点检测,之后结合不同的描述子进行影像特征匹配,并对所检测的特征点的重复率及其描述子进行适应性实验,以此来判断不同算法对不同地物特征的影像适应范围。实验数据表明:针对特征点适应性实验,AKAZE算法在各类影像上所提取的特征点相对比较稳定;针对特征点匹配实验,在影像不涉及旋转变化时,AKAZE与SIFT描述子结合进行特征点匹配,影像的匹配率显著提高;若要实现影像的旋转不变性,此时可选用SURF-SIFT、AKAZE。     

三线阵CCD影像的像点自动匹配技术研究

目前国内针对三线阵CCD影像像点自动量测技术研究比较少,主要采用常规影像匹配方法进行处理。本文在分析众多匹配方法的基础上,根据三线阵CCD影像的特点,在立体环境下对三线阵CCD影像空三加密像点自动量测的方法进行研究。用实验的方法研究了基于金字塔分层动态窗口匹配运算的相关系数法在三线阵CCD影像像点立体匹配中的应用,最后通过三线阵CCD数字模拟影像试验,得出结论:采用金字塔分层动态窗口匹配运算的相关系数法是解决三线阵CCD影像空三加密像点自动量测问题比较有效的途径。     

环境一号卫星CCD数据在1:250000地形图框架要素更新中的应用能力研究

探讨了采用环境一号卫星CCD多光谱数据在1∶250 000地形图框架要素更新中的应用情况,对不同框架要素在环境一号卫星CCD影像中的识别率和最小分辨率进行了比较和分析,并对环境一号卫星CCD影像的分辨能力和要素识别精度进行了分析和研究,进一步证实了采用环境一号卫星CCD数据进行1∶250 000地形图框架要素进行更新的可行性。     

基于准不变目标物下CBERS-02星CCD图像的交叉定标

提出了一种基于准不变反射率地物的交叉定标方法,首先用MODTRAN模式从已知定标系数的影像中反演出反射率,然后计算出对应未知定标系数影像中相同准不变地物的辐射率,最后求出定标系数.将这种方法应用于CBERS-02卫星CCD影像定标,并用6S模式对CBERS-02和ETM+影像进行大气校正,比较用不同定标系数校正后的地物光谱曲线,得出在高反射率地物下,不同定标系数校正后的地物光谱曲线与ETM+的基本一致;低反射率地物下,单点定标系数误差较大,两点定标系数误差较小,用两点定标系数进行大气校正后植被信息得到明显增强.     

一种非共线TDI CCD成像数据内视场拼接方法

星载非共线TDI CCD成像数据的高质量内视场拼接是保证影像后续处理和应用的基础。本文提出了一种非共线TDI CCD成像数据内视场拼接方法,该方法基于物方投影面和相机的传感器几何模型,建立了从拼接影像像点到原始影像像点的坐标转换关系,进而采用间接法影像纠正的方式对原始影像进行重采样生成拼接影像。本文在描述非共线TDI CCD严格成像几何模型之后,详细叙述了方法的基本原理、潜在的误差来源以及方法的实现流程,并通过ZY-1 02C卫星的高分辨率（HR）相机成像数据进行了试验验证,对拼接精度的分析与评价证明了方法的可行性。     

CBERS-02B卫星WFI成像在轨MTF估算与图像MTF补偿

基于高分辨率图像对比法, 利用同一卫星平台上空间分辨率19.5m的CCD相机图像对CBERS-02B卫星上空间分辨率为258m的 WFI成像仪图像进行在轨MTF(modulate transfer function)测量, 获得WFI(wide field imager)相机沿轨、跨轨与45o方向的MTF曲线, 并计算出3个方向的线扩展函数LSF(line spread function), 获得3个方向的有效半带宽。结果表明WFI相机红波段跨轨、沿轨与45o方向的有效半带宽, 即有效瞬时视场, 分别为1.188, 1.165与1.281个像元, 近红外波段为1.258, 1.195与1.326个像元。基于获得的MTF, 利用维纳滤波法对WFI图像进行补偿, 部分恢复了WFI图像的细部信息。     

FY-3微波成像仪遥感图像地理定位方法研究

MWRI (MicroWave Radiation Imager) is one of the payloads on our next generation polar meteorological satellite FY-3. MWRI conically scans with a fixed incident angle on the earth surface. It is the first time for Chinese remote sensor to use this scan mode. In this work, we present a geolocation method for FY-3 MWRI’s remote sensing image based on its special scan geometry. The integrated coordinate systems and the specific relationships with these coordinate systems are defined. A spatial relationship model between the remote sensing data and the earth-based coordinate system is established. This method also includes an algorithm of satellite orbit computation, which is used to get the satellite’s instantaneous velocity vector from its position. This method has been applied to MWRI’s remote sensing image geolocation. The results show that the accuracy of this method can achieve 1 pixel. The 33 GCPs (Ground Control Points) which are in the regiones of FY-3 MWRI’s observation have been collected and used to analyze the precision of the geolocation. By statistical analysis, the error along-track is about 1.5km, and the error along-scan is about 3.0km. It is obvious that this method fulfills the requirement of precision for FY-3 MWRI whose space resolution exceeds 5km.     

渤海近岸水体漫衰减系数Kd(490)遥感反演模型

Irrigated land is one of the most important parts in land cover classification system, but until now it has seldom been reported about extracting it from remote sensing data and monitoring its dynamic change. The existing researches are focused on the land use-cover change (LUCC) and the irrigated area mapping, so the study on extracting irrigated land is much more important. On the basis of close relationship between water deficit index (WDI) and soil water content, this paper firstly combines two neighbor NDVI and the surface-air temperature (Ts-Ta) and conforms one Vegetation Index Temperature (VIT). It makes the timely incomparable WDI comparable and then computes the change of WDI during the monitored period. Secondly it infers the change of soil water. Thirdly it removes the rainfall’s influence under some assumption and extracts the irrigated land of the survey area. Results show that comparing with census data all the deviation is below 7% in the survey area except Shanxi province, which means that the extracted results are comparable with census data. Extracted irrigated land mainly distributes around rivers, lakes, and reservoirs or on the irrigated regions and oasises. The results are consistent with the centralized region which has abundant irrigated land known before. The results are checked elementarily using TM images. All the precisions are above 70% except in Shanxi province. The precision in Xinjiang municipality is the highest.     

Radiometric correction of hemispherical images

Light scattering in fore-optics of imaging radiometric instruments degrades images, the signal of dark pixels is enhanced and that of bright pixels is reduced. A procedure of restoring hemispherical images obtained with a hemispheric view CCD-radiometer is suggested. The circular hemispheric image is projected onto the sphere and Wiener filtering on the sphere is performed. For building the Wiener filter the point spread function of the instrument was measured in the laboratory, and test images of (partially) controlled radiance were measured. The procedure is applied for the correction of hemispherical radiometric images taken under forest canopy. In non-corrected near infrared images the signal of sky pixels in forest canopy gaps near zenith is enhanced 1.4–2.0 times. The applied correction reduces this error to the level of 1.1–1.2. In the red channel these figures are 0.8–0.9 and 0.97–0.99, respectively.     

HIGH PRECISION CCD CALIBRATION AND ITS APPLICATIONS

With the help of CCD images,the realization of high precision po-sitioning and measurement has become the basic standard for machine vision andreal time photogrammetry systems.However,deformation and other sorts ofdegradation occurring during transmission are major limiting factors of the preci-sion attainable with most current CCD cameras and frame grabbers.So a preciseradiometric and geometric transmission of images from CCD sensor to memory is afundamental aspect of CCD camera calibration.The geometric calibration system,which uses some image processing algorithms of the CCD camera based on the re-searched and developed system is discussed.The reliability and validity are alsodiscussed.The experimental results for the calibration of the CCD array will betaken as an important quality index for CCD evaluation.     

HIGH PRECISION CCD CALIBRATION AND ITS APPLICATIONS

ABSTRACT

With the help of CCD images, the realization of high precision positioning and measurement has become the basic standard for machine vision and real time photogrammetry systems. However, deformation and other sorts of degradation occurring during transmission are major limiting factors of the precision attainable with most current CCD cameras and frame grabbers. So a precise radiometric and geometric transmission of images from CCD sensor to memory is a fundamental aspect of CCD camera calibration. The geometric calibration system, which uses some image processing algorithms of the CCD camera based on the researched and developed system is discussed. The reliability and validity are also discussed. The experimental results for the calibration of the CCD array will be taken as an important quality index for CCD evaluation.     

A novel image-fusion method based on the un-mixing of mixed MS sub-pixels regarding high-resolution DSM

A major reason for the spectral distortions of fused images generated by current image-fusion methods is that the fused versions of mixed multispectral (MS) sub-pixels (MSPs) corresponding to panchromatic (PAN) pure pixels remain mixed. The MSPs can be un-mixed spectrally to pure pixels having the same land cover classes in a fine classification map during the fusion process. Since it is difficult to produce such a land cover classification map using only MS and PAN images, a Digital Surface Model (DSM) derived from airborne Light Detection And Ranging data were employed in this study to facilitate the classification. In a novel fusion method proposed in this paper, MSPs near and across boundaries between vegetation and non-vegetation are identified using MS, PAN, and normalized Digital Surface Model (nDSM). The identified MSPs then are fused to pure pixels with respect to the corresponding land cover class in the classification map. In a test on WorldView-2 images over an urban area and the corresponding nDSM, the fused image generated by the proposed method was visually and quantitatively compared with fused images obtained using common image-fusion methods. The fused images generated by the proposed method yielded minimal spectral distortions and sharpened boundaries between vegetation and non-vegetation.     

基于多特征对象的高分辨率遥感影像分类方法及其应用

提出了基于多特征对象的高分辨率遥感影像分类方法，分析了该方法相对于基于像元的和单纯依靠光谱特征的传统处理方式所具有的优势，总结了该方法的特点，并给出了相关实验结果。实验表明，对于高分辨率遥感影像，基于多特征对象的分类技术能产生较好的结果。     

Evaluation of different topographic correction methods for Landsat imagery

The recent free availability of Landsat historical data provides new potentials for land-cover change studies. Multi-temporal studies require a previous radiometric and geometric homogenization of input images, to better identify true changes. Topographic normalization is one of the key steps to create consistent and radiometricly stable multi-temporal time series, since terrain shadows change throughout time. This paper aims to evaluate different methods for topographic correction of Landsat TM-ETM+ data. They were assessed for 15 ETM+ images taken under different illumination conditions, using two criteria: (a) reduction of the standard deviation (SD) for different land-covers and (b) increase in temporal stability of a time series for individual pixels. We observed that results improve when land-cover classes where processed independently when applying the more advanced correction algorithms such as the C-correction and the Minnaert correction. Best results were obtaining for the C-correction and the empiric–statistic correction. Decreases of the SD for bare soil pixels were larger than 100% for the C-correction and the empiric–statistic correction method compared to the other correction methods in the visible spectrum and larger than 50% in the IR region. In almost all tests the empiric–statistic method provided better results than the C-correction. When analyzing the multi-temporal stability, pixels under bad illumination conditions (northern orientation) improved after correction, while a deterioration was observed for pixels under good illumination conditions (southern orientation). Taken this observation into account, a simple but robust method for topographic correction of Landsat imagery is proposed.