天绘一号卫星无地面控制点摄影测量关键技术及其发展历程

本文介绍了天绘一号卫星立项前的预先研究和试验工作、摄影测量研究历程框架以及关键的学术思想。EFP多功能光束法平差结果表明:无地面控制点目标定位精度达到工程技术指标,并与美国SRTM相对精度相当。此外,笔者还简要地介绍了国外主要传输型卫星无地面控制点摄影测量历程。     

Effect of Contour Intervals and Grid Cell Size on the Accuracy of DEMs and Slope Derivatives

Digital Elevation Models (DEMs) are indispensable tools in many environmental and natural resource applications. DEMs are frequently derived from contour lines. The accuracy of such DEMs depends on different factors. This research investigates the effect of sampling density used to derive contours, vertical interval between contours (spacing), grid cell size of the DEM (resolution), terrain complexity, and spatial filtering on the accuracy of the DEM and the slope derivative. The study indicated different alternatives to achieve an acceptable accuracy depending on the contour interval, the DEM resolution and the complexity of the terrain. The effect of these factors on the accuracy of the DEM and the slope derivative was quantified using models that determine the level of accuracy (RMSE). The implementation of the models will guide users to select the best combination to improve the results in areas with similar topography. For areas with variable terrain complexity, the suggestion is to generate DEMs and slope at a suitable resolution for each terrain separately and then to merge the results to produce one final layer for the whole area. This will provide accurate estimates of elevation and slope, and subsequently improve the analyses that rely on these digital derivatives.     

利用多源空间数据进行地形的三维变化检测

本文提出了利用空间数据库中已有的DEM、DOM、DLG和新影像进行三维变化检测,在此基础上提取二维变化信息的技术框架。探讨了基于DEM的VLL物方影像匹配方法、多尺度表达的数字高程模型,以及自适应窗口大小和变化阈值的确定等用于三维变化检测的关键技术。这些思想和方法在实验中得到初步证实。     

基于变化检测的DOM与DEM数据同步更新

针对现有DOM与DEM生产模式不能满足数字城市、智慧城市信息化建设的需要和信息化测绘体系的网络化、自动化更新需求,该文提出了基于变化检测的DOM与DEM网络化同步编辑更新方法,形成一套针对变化区域的快速更新技术流程。完成了DOM与DEM网络化快速编辑更新平台的研发,基于网络并行环境实现网络化任务分发、多人员同步编辑的生产更新模式。通过丽水和平湖两个测区的生产实践,结果表明总体效率比传统生产方式提高27%左右。     

利用多时相DEM数据的冰雪覆盖体量变化计算方法研究

提出了利用同一研究区不同时相且无地质灾害发生情况下数字高程模型(DEM)的差异来计算冰雪覆盖体量变化的方法。设计实现了两种DEM主要表达形式(规则格网DEM和TIN)的冰雪覆盖体量变化计算方法,提出基于三维道格拉斯-普克算法的DEM数据综合方法,减少离散点数量,从而提高建立TIN网的速度以及体积变化计算速度。最后以天山乌鲁木齐河流域数据为例对两种计算方法进行了实验验证。     

地质灾区光学立体影像植被与3维地形定量变化检测

当前,经典的2维遥感变化检测方法不再适用于地质灾害引起的地表3维变化。此外,一般植被提取依赖近红外波段,而近红外影像未必能获取。因此,针对2010年和2011年汶川映秀地区的可见光航空立体像对,提出了一种检测植被和3维地形变化的方法。首先,生成研究区两个不同时期的DEM和DOM并完成配准,再利用CIE Lab色彩空间和Otsu分割算法对可见光DOM进行植被变化检测。然后,基于概率统计理论对新旧时期差分DEM提出了3维变化检测的自适应阈值确定方法,在高概率置信域条件下提取出地质灾害的高危区域。最后,对高危区域运用离散化积分方法估算出土方量的3维变化量。实验结果表明了所提出方法的可行性,有效性和实用性。本文不仅将常规遥感的2维变化检测升华至3维空间,而且对变化的3维地形进行了定量估计,可应用于地质灾害的遥感动态监测和评估。     

“天绘一号”卫星无地面控制点EFP多功能光束法平差

无地面控制点卫星摄影测量是实现全球测绘的有效手段。实现无地面控制点摄影测量主要途径包括:一是卫星姿态稳定度达到1×10^-6(°/s);二是高精度的姿态测定系统;三是摄影测量光束法平差处理。以往受制于技术等因素, 实现无地面控制点摄影测量只能依靠摄影测量光束法平差技术。“天绘一号”卫星研发了集相机在轨标定、全三线交会光束法平差、角元素低频误差补偿及偏流角效应改正为一体的EFP多功能光束法平差技术, 并通过“天绘一号”卫星影像数据对该技术进行了验证。实验结果表明:无地面控制点定位精度达到10.3 m/5.7 m(平面/高程), 满足测制1:5万比例尺地形图精度要求     

A FRAMEWORK FOR AUTOMATED CHANGE DETECTION SYSTEM

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A framework for automated change detection system

To enhance the ability of remote sensing system to provide accurate, timely, and complete geo-spatial information at regional or global scale, an automated change detection system has been and will continue to be one of the important and challenging problems in remote sensing. In this paper, the authors propose a framework for automated change detection system at landscape level using various geo-spatial data sources including multi-sensor remotely sensed imagery and ancillary data layers. In this framework, database is the central part and some associated techniques are discussed. These techniques includes five subsystems: automated feature-based image registration, automated change finding, automated change feature extraction and identification, intelligent change recognition, change accuracy assessment and database updating and visualization.     

Automatic Change Detection for Road Networks from Images Based on GIS

Up to now, detailed strategies and algorithms of automatic change detection for road networks based on GIS have not been discussed. This paper discusses two different strategies of automatic change detection for images with low resolution and high resolution using old GIS data, and presents a buffer detection and tracing algorithm for detecting road from low-resolution images and a new profile tracing algorithm for detecting road from high-resolution images. For feature-level change detection (FL-CD), a so-called buffer detection algorithm is proposed to detect changes of features. Some ideas and algorithms of using GIS prior information and some context information such as substructures of road in high-resolution images to assist road detection and extraction are described in detail.     

Automatic change detection for road networks from images based on GIS

Up to now, detailed strategies and algorithms of automatic change detection for road networks based on GIS have not been discussed. This paper discusses two different strategies of automatic change detection for images with low resolution and high resolution using old GIS data, and presents a buffer detection and tracing algorithm for detecting road from low-resolution images and a new profile tracing algorithm for detecting road from high-resolution images. For feature-level change detection (FL-CD), a so-called buffer detection algorithm is proposed to detect changes of features. Some ideas and algorithms of using GIS prior information and some context information such as substructures of road in high-resolution images to assist road detection and extraction are described in detail.     

A new approach for vegetation change detection in urban areas

Because of complex change in urban areas, modified CVA application based on mask techniques can minify the effect of non-vegetation changes and improve upon efficiency to a great extent. Moreover, drawing from methods in polar plots, the technique measures changes with absolute angular and total magnitude of PVI calculated on the basis of linear fit with least-square estimation and GVI calculated using 3D G-S transformation. Finally, this application is performed with Landsat ETM+ imageries of Wuhan in 2002 and 2005, and assessed by error matrix, in the way it could detect change pixels 94.91% correct, and the total consistent coefficient Kappa and could reach to 0.85. The evaluation result demonstrates this new application trends as an efficient and effective alternative to urban vegetation change extraction.     

A new approach for vegetation change detection in urban areas

IntroductionVegetation distribution and change is regardedas ani mportant sign of urban environment . Withcity expanding and population increasing, herecomes a series of problems on environment ,andmoreover ,greening ratio is regarded as a stand-ard of ci…     

影像与激光雷达数据的城市地物信息提取

针对城市地物信息提取中地物边界难以确定、分类精度不高的问题,该文提出一套综合利用影像及激光雷达点云高程信息的面向对象分类方法。在分割中,各类地物的最佳分割尺度由监督法分割精度评价确定,最终分割结果利用粒度理论下的分割尺度综合方法进行合成,能兼顾不同地物最优分割尺度,获得准确地物边界;在分类中,采用ReliefF特征选择算法度量从影像及点云数据提取的对象特征重要度,选择最佳特征组合,并采用多分类器组合方法进行分类,以消除Hughes现象,提高分类精度。选择德国斯图加特市两块实验区进行分类实验,结果表明:该方法有利于提高大范围城市地物精细信息提取的精度和效率,具有较高的应用价值。     

无地面控制点条件下卫星摄影测量的发展与现状

无地面控制点条件下, 卫星摄影测量研究与工程实践是世界各国在该领域中所面临的研究难点之一。本文介绍了在无地面控制条件下光学卫星摄影测量的研究发展和工程实践历程, 并对中国“天绘一号”卫星获取的影像实测结果进行分析, 结果表明, 中国在无地面控制条件下的卫星摄影测量研究与工程实践已居于国际领先地位。     

Automatic change detection of geo-spatial data from imagery

The problems and diffi-culty of current change detection tech-niques are presented. Then, according to whether image registration is done before change detection algorithms,the authors classify the change detec-tion into two categories:the change de-tection after image registration and the change detection simultaneous with image registration. For the former,four topics including the change detec-tion between new image and old im-age, the change detection between new image and old map, the change detec-tion between new image/old image and old map, and the change detection be-tween new multi-source images and old map/image are introduced. For the latter, three categories, i. e. the change detection between old DEM,DOM and new non-rectification image,the change detection between old DLG, DRG and new non-rectification image, and the 3D change detection between old 4D products and new multi-overlapped photos, are dis-cussed.     

面向对象的高分辨率遥感影像建设用地变化监测

建设用地变化监测对城市可持续发展具有十分重要的意义,为准确提取建设用地的变化信息,本文提出了一种结合旧时期土地利用矢量数据、随机森林及模糊C均值聚类算法的建设用地变化监测方法.首先基于旧时期土地利用矢量数据,将建设用地变化监测分为建成区与非建成区建设用地变化监测;然后进行面向对象分割、基于对象遥感影像光谱、GLCM纹理...     

基于时空域密度异常的土地利用/土地覆盖短期变化检测

论文分析了时间序列遥感影像中土地利用/土地覆盖短期变化的特点及其时空异常特征, 认为和环境、物候等因素造成的影像变化相比, 由人为活动引起的土地利用/土地覆盖变化具有典型的时间和空间异常特征, 并提出了基于密度异常的土地利用短期变化检测方法。研究工作选取珠江口地区1—5月作物生长期间的3个时间序列Radarsat雷达影像进行试验, 在影像分割的基础上, 构建了基于对象的特征变化矢量, 并将密度异常检测算法(DBAD)扩展到变化矢量的N维特征空间上, 运用随机搜索策略确定检测参数, 对Radarsat时间序列变化矢量中的“小模式”事件进行了检测。检测结果认为, 密度异常检测算法检测的是变化矢量在特征空间的密度分布, 与变化矢量的强度和方向无关, 因此能在时间序列影像中分离出由典型的、正常的作物生长或农事活动引起的影像光谱或回波变化, 进而识别出由人为活动或突发事件导致的土地利用/土地覆盖变化, 这是通常的图像差值等方法难以做到的。进一步的抽样检测说明, 密度异常检测方法对新增建设用地的检测准确率最高(>88%);林地地表覆盖相对稳定, 检测误差也很低(8%);农用地和养殖水面的异常变化检测误差在11%—22%之间;较大的检测误差主要集中在建设用地、农用地和未利用地之间的转换(16%—25%);此外, 养殖水面的检测误差主要集中在河流沿岸及水面变化较大的养殖区域。影像分割结果特别是一些线状分割图斑以及混合地类图斑对误差也有一定的影响。     

基于MODIS 250m遥感影像的变化检测

本文采用分辨率为250m的MODIS遥感影像对土地利用类型进行动态监测,其目的是探讨在MODIS影像上,能够快速准确地获取在不同时期的变化信息,并且为进一步分析提供参考。本文主要讨论运用MODIS影像进行变化检测的几个方面:一是相对辐射校正;二是变化区域的确定,采用基于像素的阈值分割和基于区域的松弛法进来确认变化/非变化像元,并提出一种基于缓冲区方法来消除部分伪变化信息;三是精度评价,根据MO-DIS高时相的特点,本文提出了基于缺少实地观测数据情况下的精度评价。     

Automatic road change detection and GIS updating from high spatial remotely-sensed imagery

This paper presents a framework for road network change detection in order to update the Canadian National Topographic DataBase (NTDB). The methodology has been developed on the basis of road extraction from IRS-pan images (with a 5.8 m spatial resolution) by using a wavelet approach. The feature matching and conflation techniques are used to road change detection and updating. Elementary experiments have showed that the proposed framework could be used for developing an operational road database updating system.