高灵敏度机载L波段微波辐射计探测海表盐度

海水盐度是研究大洋环流和全球气候变化的重要参数,L波段(1400-1427MHz)微波辐射计是进行海水盐度遥感的最有效工具.在该频段内,微波辐射亮度温度对海水盐度变化的灵敏度为0.5K/psu,而用于海洋研究的盐度分辨率为0.1-0.2psu,要求微波辐射计的灵敏度优于0.1K.高灵敏度机载L波段微波辐射计,应用数字增益波动自动补偿和温度补偿技术,保证了系统的稳定性,并采用高效的滤波技术有效地抑制了全球定位信号(GPS)对接收机的干扰,灵敏度达到0.08K.进行了多次航空和海上对比遥感试验,获得了分辨率优于0.2psu、误差精度0.42psu的测量结果.     

基于NSWT模极大值的PSF估计

大气湍流扰动严重影响了空间目标的观测、成像和识别。在目标图像的重建过程中,对成像系统和大气条件先验知识的缺乏使PSF（Point Spread Function）的估计成为解决病态问题的重要内容。在NSWT（NonSubsampled Wavelet Transform）和Fried参数的理论基础上,根据不同尺度下小波变换模极大值和高斯点扩散函数方差的关系,结合Fried参数提出一种新的估计方法,即基于非抽取小波变换模极大值的PSF估计算法。实验结果证明,该估计算法是确实可行的,重建的PSF能够有效地改善因受大气湍流影响的图像解卷积的效果。     

随机Dirichlet问题解的调和展开

针对重力学随机Dirichlet问题,通过适当地对边界检验函数的分解,并在随机边界样本空间中提取确定性部分的对偶基,本文将随机Dirichlet问题的一般解展开为一随机系数的调和级数形式。     

地面移动测量技术的发展与现状

地面移动测量技术是当前倍受关注的测量前沿技术。本文论述了地面移动测量技术的基本原理和特点，回顾了该技术的发展历史，总结了国内外研究现状，展望了今后的发展趋势与应用前景，并对研究、发展和应用这一技术提出了建议。     

Accuracy assessment of lidar-derived digital elevation models

Despite the relatively high cost of airborne lidar-derived digital elevation models (DEMs), such products are usually presented without a satisfactory associated estimate of accuracy. For the most part, DEM accuracy estimates are typically provided by comparing lidar heights against a finite sample of check point coordinates from an independent source of higher accuracy, supposing a normal distribution of the derived height differences or errors. This paper proposes a new methodology to assess the vertical accuracy of lidar DEMs using confidence intervals constructed from a finite sample of errors computed at check points. A non-parametric approach has been tested where no particular error distribution is assumed, making the proposed methodology especially applicable to non-normal error distributions of the type usually found in DEMs derived from lidar. The performance of the proposed model was experimentally validated using Monte Carlo simulation on 18 vertical error data-sets. Fifteen of these data-sets were computed from original lidar data provided by the International Society for Photogrammetry and Remote Sensing Working Group III/3, using their respective filtered reference data as ground truth. The three remaining data-sets were provided by the Natural Environment Research Council's Airborne Research and Survey Facility lidar system, together with check points acquired using high precision kinematic GPS. The results proved promising, the proposed models reproducing the statistical behaviour of vertical errors of lidar using a favourable number of check points, even in the cases of data-sets with non-normally distributed residuals. This research can therefore be considered as a potentially important step towards improving the quality control of lidar-derived DEMs.     

Regional yield estimation for winter wheat with MODIS-NDVI data in Shandong, China

The significance of crop yield estimation is well known in agricultural management and policy development at regional and national levels. The primary objective of this study was to test the suitability of the method, depending on predicted crop production, to estimate crop yield with a MODIS-NDVI-based model on a regional scale. In this paper, MODIS-NDVI data, with a 250 m resolution, was used to estimate the winter wheat (Triticum aestivum L.) yield in one of the main winter-wheat-growing regions. Our study region is located in Jining, Shandong Province. In order to improve the quality of remote sensing data and the accuracy of yield prediction, especially to eliminate the cloud-contaminated data and abnormal data in the MODIS-NDVI series, the Savitzky–Golay filter was applied to smooth the 10-day NDVI data. The spatial accumulation of NDVI at the county level was used to test its relationship with winter wheat production in the study area. A linear regressive relationship between the spatial accumulation of NDVI and the production of winter wheat was established using a stepwise regression method. The average yield was derived from predicted production divided by the growing acreage of winter wheat on a county level. Finally, the results were validated by the ground survey data, and the errors were compared with the errors of agro-climate models. The results showed that the relative errors of the predicted yield using MODIS-NDVI are between −4.62% and 5.40% and that whole RMSE was 214.16 kg ha⁻¹ lower than the RMSE (233.35 kg ha⁻¹) of agro-climate models in this study region. A good predicted yield data of winter wheat could be got about 40 days ahead of harvest time, i.e. at the booting-heading stage of winter wheat. The method suggested in this paper was good for predicting regional winter wheat production and yield estimation.     

基于Web Service的Web地图服务设计与实践

集成和互操作一直是GIS发展的热点问题,而在互联网时代背景下产生的Web服务(Web Service)技术为GIS的集成和互操作提供了全新的、有效的解决途径。在介绍和分析Web服务技术的基础上,提出并实践了一种将地图服务的基本功能包装成Web服务进行发布的思路。通过将GIS的基本功能包装成Web服务,可以实现使用一种标准的协议来实现各GIS应用系统的交互和集成,屏蔽了系统间软、硬件平台的不同。     

基于数据库的大比例尺基础地理数据缩编需要注意的一些问题

提出了基于数据库的大比例尺基础地理数据缩编需要注意的一些问题，并从加强数据设计的完整性、作好数据准备工作，提高自动化处理功能，人机交互辅助缩编，满足地图回放的要求，加强数据质量控制等方面阐述了实现基于数据库缩编的实用方法。     

室内定轨移动摄影测量控制系统设计与实现

在室内定轨移动摄影测量系统中,自动化、智能化的控制系统是其稳定可靠工作的重要保障.该摄影测量系统需要对轨道上的移动平台和摄影测量机构进行远程操作,为了实现稳定、可靠的控制,设计研发以单片机为控制核心的遥控系统;摄影测量机构是由五台非量测数码相机拼接而成,为了实现五台相机同步摄影,设计完成相机同步曝光装置.实验表明该系统...