改进IHS变换的图像融合方法研究     

张丽侠  张力  艾海滨 《测绘科学》2011,36(6):149-151,143

经典的IHS变换融合以其快速、简单的特点得到广泛应用,但该方法在显著提高图像空间分辨率的同时引起了严重的光谱失真.本文分析了IHS变换引起光谱失真的原因,并总结了已有的针对光谱失真的IHS变换改进算法,提出基于小波的IHS变换融合,利用小波分解尽可能地保留了原I分量中的光谱信息,在提高空间分辨率的同时减少了光谱失真.实...  相似文献   

最小体积约束的线性光谱解混算法     

李二森  徐波  李娜  周晓明 《武汉大学学报(信息科学版)》2011,(6):683-686

提出了最小体积单体约束的线性光谱解混算法。该算法不需要假设数据中存在纯像元,采用二次规划方法计算降维后的端元矩阵,利用最小二乘方法实现丰度估计和端元提取。实验结果表明,此算法解混的结果整体上优于MVC-NMF算法。  相似文献   

利用光谱角敏感森林的高光谱数据快速匹配方法     

周源  方圣辉  李德仁 《武汉大学学报(信息科学版)》2011,(6):687-690

提出了一种新的光谱匹配算法——光谱角敏感森林方法。在位置敏感哈希函数算法的基础上引入光谱角度量,并利用新的数据桶检索结构改进了原位置敏感哈希函数算法中部分目标光谱点无法得到匹配光谱的缺陷。理论和实验证明,光谱角敏感森林算法的计算效率较传统高维数据匹配方法有较明显优势。  相似文献   

Imaging spectroscopy in soil-water based site suitability assessment for artificial regeneration to Scots pine     

Maarit Middleton  Paavo Nrhi  Raimo Sutinen 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(3):287-297

In a humid northern boreal climate, the success rate of artificial regeneration to Scots pine (Pinus sylvestris L.) can be improved by including a soil water content (SWC) based assessment of site suitability in the reforestation planning process. This paper introduces an application of airborne visible-near-infrared imaging spectroscopic data to identify suitable subregions of forest compartments for the low SWC-tolerant Scots pine. The spatial patterns of understorey plant species communities, recorded by the AISA (Airborne Imaging Spectrometer for Applications) sensor, were demonstrated to be dependant on the underlying SWC. According to the nonmetric multidimensional scaling and correlation results twelve understorey species were found to be most abundant on sites with high soil SWCs. The abundance of bare soil, rocks and abundance of more than ten species indicated low soil SWCs. The spatial patterns of understorey are attributed to time-stability of the underlying SWC patterns. A supervised artificial neural network (radial basis functional link network, probabilistic neural network) approach was taken to classify AISA imaging spectrometer data with dielectric (as a measure volumetric SWC) ground referencing into regimes suitable and unsuitable for Scots pine. The accuracy assessment with receiver operating characteristics curves demonstrated a maximum of 74.1% area under the curve values which indicated moderate success of the NN modelling. The results signified the importance of the training set’s quality, adequate quantity (>2.43 points/ha) and NN algorithm selection over the NN algorithm training parameter optimization to perfection. This methodology for the analysis of site suitability of Scots pine can be recommended, especially when artificial regeneration of former mixed wood Norway spruce (Picea abies L. Karst) - downy birch (Betula pubenscens Ehrh.) stands is being considered, so that artificially regenerated areas to Scots pine can be optimized for forestry purposes.  相似文献   

Water Vapor and Cloud Radiative Forcings over the Pacific Ocean Simulated by the LASG/IAP AGCM: Sensitivity to Convection Schemes   总被引：3，自引：0，他引：3  

WU Chunqiang  ZHOU Tianjun  SUN De-Zheng  BAO Qing 《大气科学进展》2011,28(1):80-98

Characteristics of the total clear-sky greenhouse effect (GA) and cloud radiative forcings (CRFs), along with the radiative-related water vapor and cloud properties simulated by the Spectral Atmospheric Model developed by LASGIAP (SAMIL) are evaluated. Impacts of the convection scheme on the simulation of CRFs are discussed by using two AMIP (Atmospheric Model Inter-comparison Project) type simulations employing different convection schemes: the new Zhang-McFarlane (NZH) and Tiedtke (TDK) convection schemes. It shows that both the climatological GA and its response to El Nio warming are simulated well, both in terms of spatial pattern and magnitude. The impact of the convection scheme on GA is not significant. The climatological longwave CRF (LWCRF) and its response to El Nio warming are simulated well, but with a prominently weaker magnitude. The simulation of the climatology (response) of LWCRF in the NZH (TDK) run is slightly more realistic than in the TDK (NZH) simulation, indicating significant impacts of the convection scheme. The shortwave CRF (SWCRF) shows large biases in both spatial pattern and magnitude, and the results from the TDK run are better than those from the NZH run. A spuriously excessive negative climatological SWCRF over the southeastern Pacific and an insufficient response of SWCRF to El Nio warming over the tropical Pacific are seen in the NZH run. These two biases are alleviated in the TDK run, since it produces vigorous convection, which is related to the low threshold for convection to take place. Also, impacts of the convection scheme on the cloud profile are discussed.  相似文献   

边界层风廓线仪多普勒频谱高度图综合应用初探   总被引：2，自引：2，他引：0  

吴志根  丁若洋  郑杰  陈浩君  查亚峰  李建成  胡平 《气象》2011,37(8):1006-1017

文章介绍了边界层风廓线仪多普勒频谱高度图的原理,并且给出了无降水、有降水、降雪、速度折叠、地物杂波、外界信号干扰等典型的多普勒频谱高度图型。研究发现,多普勒频谱高度图除了可以从中提取测风产品所需的数据外,该在线显示的图形还实时提供了许多其他潜在的气象信息,并可用于：连续监视测站上空天气;提前了解测站上空风的垂直切变;发现并确定降水起始时间;在线估测风向风速;实时判别降水云底高度和0°层的范围;验证和解释风羽剖面图产品中的奇异现象;帮助固定和移动风廓线仪选址;诊断风廓线仪系统故障;评价风廓线仪系统软/硬件性能优劣等。文章指出：深入发掘边界层风廓线仪在降水天气系统中进行高时间密度探测的潜力,使得它可以晴雨两用,对今后将边界层风廓线仪配备到一般气象观测站,提高单站天气监测/预警能力和开展精细化天气预报意义深远。文章还对当前商业化的边界层风廓线仪提出了具体的改进意见,以满足频谱在线分析的需要。  相似文献   

物理守恒律保真全球谱模式辐射—云—对流过程的改进   总被引：1，自引：0，他引：1  

钟琦  钟青  沈元芳 《气候与环境研究》2011,16(4):407-418

辐射—云一对流相互作用的正确和合理描述是改进湿物理过程描述和数值模式的重要方面.在一个物理守恒律保真的全球模式中引入描述更细致的云参数化方案和辐射参数化方案,对6个30天实时资料数值积分进行分析.结果表明,通过云参数化方案中云描述的细化,改进了模式对云分布、云量、以及云水、云冰不同相态的模拟;辐射方案中对这些云水物质的...  相似文献   

泉州地震台数字地震仪台址的地脉动噪声分析     

林建生  张有明  谢文杰  吴淑美  王建新 《华南地震》2011,31(1):18-28

利用2008年泉州台甚宽频带数字地震仪连续48 h和全年每月连续48 h内白天与夜间各连续4 h的地脉动记录,计算5 Hz、5 s和100s的静态地脉动噪声功率谱密度、1/3倍频程1-20Hz带宽各段的平均静态地脉动噪声有效值、1/3倍频程100-30 s带宽各段的平均静态地脉动加速度噪声有效值,以及上述3个频点和2个...  相似文献   

填充墙对底框结构地震反应的影响     

李樾  李鸿晶  施溪溪 《地震学刊》2011,(4):423-429

为研究填充墙对底层框架多层砌体房屋地震反应的影响,以典型的填充墙-底层框架多层砌体房屋为基础,建立有限元计算模型并进行了弹塑性动力时程分析。根据不同模型的计算结果以及填充墙的刚度和强度,分析了填充墙对底层框架多层砌体房屋自振周期、地震作用下房屋整体变形、底层框架的损伤以及填充墙与底层框架相互作用的影响。计算结果表明：填充墙对房屋整体地震反应产生明显影响,其影响不能忽略。在上部砌体结构质量和刚度不变的情况下,结构自振周期随着填充墙刚度的增加而降低;随着填充墙与底层框架之间连接作用的增强,结构整体的变形减小,底层框架的损伤增大。当填充墙与底层框架之间采用弱连接时,采用强度较高的填充墙可以提高结构整体的变形能力,从而提高结构整体的抗震能力。  相似文献   

混合光谱分解算法的太湖水体组分浓度反演分析     

陆超平  吕恒  李云梅 《地球信息科学学报》2011,13(5):687-694

二类水体组份的遥感定量反演一直是水色遥感的难点和热点问题,原因在于其水体组分(纯水、叶绿素、悬浮物及CDOM)之间复杂的相互作用.本文引入光谱分解算法,通过Hydrolight软件模拟叶绿素、悬浮物和CDOM的标准反射率光谱,解决光谱分解算法中“纯端元”难以获取的问题.在此基础上建立了二类水体组分光谱分解反演模型.模型...  相似文献