针对北斗系统的降维快速高精度定向算法

通过分析北斗系统的星座特点及GEO卫星特征,提出了一种针对北斗系统的快速高精度定向方法。该方法利用北斗GEO卫星东西向几何构型好的优势,首先由GEO卫星的观测值结合降维解算理论解算基线向量候选值;然后通过模糊度函数法对候选值进行判决,得到最优基线向量,解出宽巷模糊度;最后在此基础上解算B1模糊度,进行高精度定向。该方法不但可以改善利用北斗定向解算所产生的病态性,而且可以减小模糊度搜索范围,实现单历元整周模糊度快速解算。利用实测北斗星历对算法进行了仿真验证,结果表明在实时动态条件下,该方法解算B1的整周模糊度成功率为99.31%,确定的俯仰角标准差为0.07°,航向角标准差为0.13°,是一种高效快速的定向算法。     

基于资源三号卫星遥感影像的城市绿地提取

资源三号卫星是中国第一颗自主的民用高分辨率立体测绘卫星,能提供优于5 m地面分辨率的遥感影像.本文首先对资源三号卫星影像预处理过程中涉及的影像纠正、影像配准、影像融合、影像镶嵌等关键步骤进行研究,然后,对比分析三种绿地信息提取方法,最后以江苏省南京市高淳区城市绿地为例,提取建成区绿地信息并加以统计分析.实验表明,本文提出的资源三号卫星影像预处理方法切实可行,国产高分辨率遥感影像适用于城市绿地调查.     

Predicting forest carbon stocks from high resolution satellite data in dry forests of Zimbabwe: exploring the effect of the red-edge band in forest carbon stocks estimation

In this study, we tested whether the inclusion of the red-edge band as a covariate to vegetation indices improves the predictive accuracy in forest carbon estimation and mapping in savanna dry forests of Zimbabwe. Initially, we tested whether and to what extent vegetation indices (simple ratio SR, soil-adjusted vegetation index and normalized difference vegetation index) derived from high spatial resolution satellite imagery (WorldView-2) predict forest carbon stocks. Next, we tested whether inclusion of reflectance in the red-edge band as a covariate to vegetation indices improve the model's accuracy in forest carbon prediction. We used simple regression analysis to determine the nature and the strength of the relationship between forest carbon stocks and remotely sensed vegetation indices. We then used multiple regression analysis to determine whether integrating vegetation indices and reflection in the red-edge band improve forest carbon prediction. Next, we mapped the spatial variation in forest carbon stocks using the best regression model relating forest carbon stocks to remotely sensed vegetation indices and reflection in the red-edge band. Our results showed that vegetation indices alone as an explanatory variable significantly (p < 0.05) predicted forest carbon stocks with R² ranging between 45 and 63% and RMSE ranging from 10.3 to 12.9%. However, when the reflectance in the red-edge band was included in the regression models the explained variance increased to between 68 and 70% with the RMSE ranging between 9.56 and 10.1%. A combination of SR and reflectance in the red edge produced the best predictor of forest carbon stocks. We concluded that integrating vegetation indices and reflectance in the red-edge band derived from high spatial resolution can be successfully used to estimate forest carbon in dry forests with minimal error.     

基于MODIS数据的PM2.5反演在大气污染监测中的应用

针对基于传统10km气溶胶光学厚度产品计算PM2.5无法获得更为精细的PM2.5空间分布特征的问题,提出采用6S模型计算获得不同气溶胶光学厚度条件下辐射传输模型方程参数查找表,该查找表可以采用原始光谱波段信息进行数据反演,并结合暗像元法计算得到的地表反射率信息,在辐射传输模型方程计算结果的基础上进行线性插值获得1km气溶胶光学厚度,再利用地面实测PM2.5浓度数据,通过回归分析的方法,获得1km的PM2.5监测数据。以西安市为例,1km分辨率的PM2.5更进一步表现了西安市域内PM2.5的空间分布特征,具有明显的地形分异特征,而且呈现出从城区向郊区逐渐衰减的趋势。研究结果为小区域的PM2.5来源和变化分析提供了一种有效的技术途径。     

Multispectral sensor spectral resolution simulations for generation of hyperspectral vegetation indices from Hyperion data

The use of multispectral satellite sensors for generation of hyperspectral indices is restricted because of their coarse spectral resolutions. In this study, we attempted to synthesize a few of these hyperspectral indices, viz. RedEdge Normalized Difference Vegetation Index (NDVI₇₀₅), Plant Senescence Reflectance Index (PSRI) and Normalized-Difference-Infrared-Index (NDII), for crop stress monitoring at regional scale using multispectral images, simulated from Hyperion data. The Hyperion data were resampled and simulated to corresponding spatial and spectral resolutions of AWiFS, OCM-2 and MODIS sensors using their respective filter function. Different possible combinations of two bands (i.e. simple difference, simple ratio and normalized difference) were computed using synthetic spectral bands of each sensor, and were regressed with NDVI₇₀₅, PSRI and NDII. Models with highest correlation were selected and inverted on Hyperion data of another date to synthesize respective multispectral indices. Synthetic broad band indices of multispectral sensors with their respective narrow band indices of Hyperion were found to be in good agreement.     

高分辨率三线阵卫星遥感影像的区域网平差算法与试验

简述高分辨率遥感卫星影像的几何定位处理过程,分析了区域网平差的必要性。结合线阵传感器的成像特点,对传感器严格几何模型、卫星轨道模型、传感器内方位误差模型进行研究,初步建立了高分辨率遥感卫星的平差数学模型。采用区域网平差方法对内方位元素和外方位元素进行解算,并利用资源三号卫星线阵影像和ALOS PRISM线阵影像进行试验。试验结果表明,对高分辨率遥感卫星线阵传感器进行区域网平差可以有效提高卫星影像的几何定位精度。     

IKONOS图像融合中自动拟合低分辨率全色图像的方法

提出了一种IKONOS图像融合中自动拟合低分辨率全色图像的方法。首先使用支持向量机将全色图像的像元自动分为高、低频信息像元;然后采用改进的Bucket技术选择一定数量、均匀分布的低频信息像元点作为观测值;最后通过线性回归方法求得拟合系数,并构造低分辨率全色图像。两组IKONOS全色与多光谱图像的实验结果表明,本文方法能自动选择均匀分布的像元点,并求得拟合系数,基于拟合低分辨率全色图像的Gram-Schmidt融合方法的质量也优于传统的Gram-Schmidt融合方法。     

中分辨率遥感图像土地利用与覆被分类的方法及精度评价

利用TM、SPOT及CBERS-1等中分辨率卫星图像,对土地覆被的专家系统分类方法、居民地的决策树提取方法以及水体的迭代混合提取方法进行了试验,其总体精度达到87.89%,与常用的监督分类方法相比精度可提高7.86%.专家系统分类的结果叠合居民地、水体等易于混分专题信息,可以形成精度较高的土地利用与覆被分类结果。     

GPS／GLONASS载波相位测量模糊度解算方法

GPS／GLONASS组合载波相位测量，在快速静态和动态定位等方面的应用具有一定的优势。由于GLONASS采用频分多址的方式识别卫星，每颗卫星的载波频率各不相同，所以在载波测量数据处理中不能采用与GPS载波相位测量数据处理相同的方法。文中就GLONASS、GPS／GLONASS组合载波相位测量整周模糊度解算的基本思路和方法进行了介绍。     

测井约束反演在高分辨率层序地层学中的应用

以新疆吐哈盆地温米油田为例 ,探讨应用测井约束地震反演资料进行高分辨率时间地层单元对比的思路和方法。研究表明 ,由于测井约束反演不仅可提高原始地震资料的垂向分辨率 ,而且可将地震波转换为层的信息 ,因此 ,据此可进行高精度的时间地层单元的追踪对比。在油田开发阶段 ,应用测井约束反演资料进行高分辨率等时地层对比的步骤包括 :地震资料的时 -深转换 ;应用地质、测井、地震资料建立宏观层序地层格架 ;测井约束地震反演处理 ;测井细分层及标定 ;时间地层单元的追踪对比