Google Earth面面观

2005年6月世界著名的搜索引擎公司美国的google提供了三维影像和矢量地图服务软件Google Earth供免费下载,同时发布了http://map. google.com网站,二者都免费提供卫星影像数据查询、矢量地图搜索、GPS导航等服务, 这立即引起了全世界互联网用户的极大兴趣,并进行疯狂的下载和浏览,导致Google的服务器不得不限制流量甚至暂时关闭。对于一个专注于互联网搜索的公司推出的地理信息服务所引起的轰动现象,值得思考。     

Google Earth及其应用展望

对Google Earth全球地理信息系统做了简单介绍,充分挖掘其功能,阐述了其在地理教学、水利工程管理、林火管理中的应用,并初步探索了其商业化应用。     

Google Earth控制点自动提取技术

控制点在遥感影像纠正等应用中有着非常重要的作用。本文针对人工选取控制点效率低、精度差的问题,提出了Google Earth高分辨率遥感影像控制点自动提取方法,说明了基于线特征确定稳定控制点的方法,并通过遥感图像纠正以及航拍图像定位实验验证了方法的有效性。     

Google Earth中类缓冲区算法

Google Earth缺乏空间分析功能,为在其中实现类似GIS软件的线状要素缓冲区分析,提出三种箅法,分别是加密点算法、点到线段距离算法和类栅格算法.结合天然气管道巡线监控系统中自动识别巡线工与管道的距离是否超限的功能,阐述三种算法的原理及优缺点比较.在精度要求不是非常严格时,此三种算法具有很强的实用价值.     

Spectral Representation and Analysis of the KBR Precision Based on the Earth Gravity Spectrum

IntroductionThe GRACE (gravity recovery and cli mate ex-peri ment) mission,twin satellites flying in for-mation ,which carries several key payloadsinclu-ding KBR (K-band ranging) system, waslaunchedin 2002 . The unique design of GRACEmissionis expected to lead to ani mprovement inseveral orders of magnitude in these gravitymeasurements and allow much i mproved resolu-tion of the Earth gravity field of finer scale overbothland and ocean to study a lot of geosciencesphenomena[1]. Though th…     

Spectral Representation Precision Based on the and Analysis of the KBR Earth Gravity Spectrum

Satellite-to-Satellite Tracking in low-low model （SST-Ⅱ） is a new technique to resolve the series of problems met in the determination of the earth＇s gravity field. As the key technique of SST-Ⅱ, KBR can get SST-Ⅱ measurements directly. So the KBR performance analysis is the first step in SST-Ⅱ design. In this paper, assuming that the satellite pairs of SST-Ⅱ are in near circle polar orbits, the spectrum relationship between the earth gravity field and KBR is established using analytic method. And then some examples are analyzed, the suggestions and conclusions are drawn from these examples. The research results could be taken as a reference for future satellite gravity project of China.     

Evaluation of the geometric stability and the accuracy potential of digital cameras — Comparing mechanical stabilisation versus parameterisation

Recent tests on the geometric stability of several digital cameras that were not designed for photogrammetric applications have shown that the accomplished accuracies in object space are either limited or that the accuracy potential is not exploited to the fullest extent. A total of 72 calibrations were calculated with four different software products for eleven digital camera models with different hardware setups, some with mechanical fixation of one or more parts. The calibration procedure was chosen in accord to a German guideline for evaluation of optical 3D measuring systems [VDI/VDE, VDI/VDE 2634 Part 1, 2002. Optical 3D Measuring Systems–Imaging Systems with Point-by-point Probing. Beuth Verlag, Berlin]. All images were taken with ringflashes which was considered a standard method for close-range photogrammetry. In cases where the flash was mounted to the lens, the force exerted on the lens tube and the camera mount greatly reduced the accomplished accuracy. Mounting the ringflash to the camera instead resulted in a large improvement of accuracy in object space. For standard calibration best accuracies in object space were accomplished with a Canon EOS 5D and a 35 mm Canon lens where the focusing tube was fixed with epoxy (47  μm maximum absolute length measurement error in object space). The fixation of the Canon lens was fairly easy and inexpensive resulting in a sevenfold increase in accuracy compared with the same lens type without modification. A similar accuracy was accomplished with a Nikon D3 when mounting the ringflash to the camera instead of the lens (52  μm maximum absolute length measurement error in object space). Parameterisation of geometric instabilities by introduction of an image variant interior orientation in the calibration process improved results for most cameras. In this case, a modified Alpa 12 WA yielded the best results (29  μm maximum absolute length measurement error in object space). Extending the parameter model with FiBun software to model not only an image variant interior orientation, but also deformations in the sensor domain of the cameras, showed significant improvements only for a small group of cameras. The Nikon D3 camera yielded the best overall accuracy (25  μm maximum absolute length measurement error in object space) with this calibration procedure indicating at the same time the presence of image invariant error in the sensor domain. Overall, calibration results showed that digital cameras can be applied for an accurate photogrammetric survey and that only a little effort was sufficient to greatly improve the accuracy potential of digital cameras.     

Length-of-day and space-geodetic determination of the Earth’s variable gravity field

The temporal variations of the Earth’s gravity field, nowadays routinely determined from satellite laser ranging (SLR) and GRACE (Gravity Recovery And Climate Experiment), are related to changes in the Earth’s rotation rate through the Earth’s inertia tensor. We study this connection from actual data by comparing the traditional length-of-day (LOD) measurements provided by the International Earth Rotation and Reference Systems Service (IERS) to the variations of the degree-2 and order-0 Stokes coefficient of the gravity field determined from fitting the orbits of the LAGEOS-1 and −2 satellites since 1985. The two series show a good correlation (0.62) and similar annual and semi-annual signals, indicating that the gravity-field-derived LOD is valuable. Our analysis also provides evidence for additional signals common to both series, especially at a period near 120 days, which could be due to hydrological effects.     

Does environmental data increase the accuracy of land use and land cover classification?

Optical image classification converts spectral data into thematic information from the spectral signature of each object in the image. However, spectral separability is influenced by intrinsic characteristics of the targets, as well as the characteristics of the images used. The classification process will present more reliable results when aspects associated with natural environments (climate, soil, relief, water, etc.) and anthropic environments (roads, constructions, urban area) begin to be considered, as they determine and guide land use and land cover (LULC). The objectives of this study are to evaluate the integration of environmental variables with spectral variables and the performance of the Random Forest algorithm in the classification of Landsat-8 OLI images, of a watershed in the Eastern Amazon, Brazil. The classification process used 96 predictive variables, involving spectral, geological, pedological, climatic and topographic data and Euclidean distances. The selection of variables to construct the predictive models was divided into two approaches: (i) data set containing only spectral variables, and (ii) set of environmental variables added to the spectral data. The variables were selected through nonlinear correlation analysis, with the Randomized Dependence Coefficient and the Recursive Feature Elimination (RFE) method, using the Random Forest classifier algorithm. The spectral variables NDVI, bands 2, 4, 5, 6 and 7 of the dry season and band 4 of the rainy season were selected in both approaches (i and ii). The Euclidean distance from the urban area, Arenosol soil class, annual precipitation, precipitation in February and precipitation of the wettest quarter were the variables selected from the auxiliary data set. This study showed that the addition of environmental data to the spectral data reduces the limitation of the latter, regarding the discrimination of the different classes of LULC, in addition to improving the accuracy of the classification. The addition of soil classes to spectral variables provided a reduction in errors for vegetation classification (Evergreen Forest and Cerrado Sensu Stricto), as it was able to inform about nutrient availability and water storage capacity. The study demonstrates that the addition of environmental variables to the spectral variables can be an alternative to improve monitoring in areas of ecotone in Neotropical regions.     

Google Earth在水利水电测绘中的应用

分析了Google Earth软件的强大功能,并详细介绍了Google Earth软件在水利水电测绘中的各种实际应用,包括水利工程断面测绘、地形图测绘、控制网优化设计、非涉密控制点成果资料管理及其他应用等,供广大水利水电测绘工作者参考。     

基于Google SketchUp与Google Earth的校园3维实现

以西南林学院为例,采用Google SketchUp创建3维建筑模型,介绍了建模方法和优化技术,并在GoogleEarth平台上发布了西南林学院校园3维全景,利用两个生活实例初步探讨了校园3维的应用功能.     

基于Google Earth的地形图制作技术

介绍一种简单新型地形图制作技术.该技术通过在Goosle Earth中建立多边形,并巧妙地将多边形转化为等高面,记录等高线来实现等高线地形图的制作,并对利用此技术制作地形图的质最进行讨论.该技术在保证一定制图精度的前提下,不但能轻松掌握,而且能缩短制图时间、降低制图成本,具有一定的创新性和推广价值.     

Google Earth影像变换与应用研究

本文通过对GE影像数据分层组织方式、数学基础的分析,以目标影像为常用的高斯一克吕格投影为例,对GE影像进行了像素图影像变换的研究。文中提出的影像变换技术可以为类似的GE影像处理与应用提供思路与方法。     

基于Google Earth的数字九寨应用

合理整合与利用旅游资源是旅游业发展的重要因素,数字化方式可以使旅游资源表现更直观、更丰富,有利于旅游资源的宣传和管理。本文以GoogleEarth为基础,对九寨旅游区进行数字化开发应用,并分析了其在GoogleEarth上的实现功能与特点。     

Google Earth矢量数据多级聚合实验

论述Google Earth矢量数据的多级组织和处理的原理及服务器端数据处理和组织的具体方法,对实验模型所取得的数据进行分析,说明多级加载的优越性。     

利用Google Earth建立等高线三维地形模型

GoogleEarth提供的免费地理坐标数据,可以作为CFD软件地形几何建模的数据源。通过C#编程提取Google Earth提供的高程数据,应用Global Mapper V11.0、Rhino 5.0等三维建模软件自动实现三维地形图几何建模,该方法简单实用,能满足CFD计算要求。     

Google Earth在航空摄影测量中的应用

分析了GoogleEarth当前的关键技术,并以酒泉风电场1：2000地形图航空摄影测量工作为倒,介绍了GoogleEarth在野外测量工作中的应用情况,并简要说明了在GoogleEarth中进行二次开发实现文件导入与导出功能,最后提出了在实际工作中应用的经验和建议.     

Google Earth和World Wind比较研究

Google Earth和World Wind是目前最具代表性的两款基于网络的三维地理信息浏览器,为空间信息的共享发布提供了新的解决思路和技术手段。本文首先深入分析了这两款软件的技术特点,并在此基础上作了比较研究。     

基于Google Earth API的二次开发研究

Google Earth是一款浏览地球三维影像的桌面软件,提供了大量多分辨率的全球影像数据,作为一个开放的地理信息服务系统,越来越多的用户以工具软件或开发平台的形式将它成功地应用在许多行业。Google Earth提供了开放的API,允许人们进行二次开发。较详细地介绍基于Google Earth API二次开发的基本知识、开发方式和开发技巧等。