共查询到20条相似文献，搜索用时 754 毫秒
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The OGC standard for 3D city modeling is widely used in an increasing number of applications.It defines five consecutive Levels of Detail(LoD0 to LoD4 with increasing accuracy and structural complexity),in which LoD3 includes all exterior appearances and geometrical details and subsequently requires much storage space.A new LoD is introduced as shell model with the exterior shell of the LoD3 model and the opening objects like windows,doors as well as smaller faade objects are projected onto walls.In this paper,a user survey is presented.The results of this survey show that the shell model can give users almost the same visual impression as the LoD3 model.Furthermroe,algorithms are developed to extract the shell model from LoD3 model.Experiments show that this shell model can reduce up to 90% storage of the original LoD3 model.Therefore,on one hand it can be used as a substitute for a LoD3 model for the visualization on small displays.On the other hand,it can be treated as a sub-level of detail(SLoD3) in CityGML,since it retains almost the same amount of information but requires much less storage space. 相似文献
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《地图》1993,(2)
d. On maps where the index and intermediate contour lines do not show the elevation and relief as accurately as may be needed, supplementary contours may be used. These contour lines are dashed brown lines, usually at one-haft the contour interval for the map. A note in the marginal information indicates the interval used. They are used exactly as are the solid contour lines. e. In addition to the contour lines on maps, bench marks and spot elevation are used to indicate points of known elevation.Bench marks are usually symbolized by an X and the elevation is given at that 相似文献
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《地图》1992,(3)
Great Circles on Cylindrical Projections Some projections show great-circle arcs as straight lines in more limited ways, such as in a single direction or along just one or two lines on the map. For example, the basic conic and cylindrical projections show north-south, groat-circle courses (meridians) as straight lines, and on cylindrical projections the great circle formed by the equator also appears as a straight line. It is possible to "force" two points to lie along one of the 相似文献
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YAO Hanbing HU Heping LU Zhengding LI Ruixuan 《地球空间信息科学学报》2006,9(3):223-228
IntroductionThe Grid security infrastructure ( GSI) hasbeen accepted as the pri mary authenticationmechanismfor the Grid computing. GSI devel-oped as part of the Globus project defines singlesign-on algorithms and protocols , cross-domainauthentication pr… 相似文献
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《地图》1989,(2)
A petroleum geoloical map is the map which represents sedimentary deposit—the interrelations between, petroleum, natural gas and the elements of physical geography and geology. It generalizes the representative methods of maps of geology, topography and section, view to show the distribution of the basins, fields of petroleum and gas as well as the geological clements and underground reliefs in detail. 相似文献
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LIJunli SUNJiabing MAOXi 《地球空间信息科学学报》2005,8(1):50-56
A new method based on resolution degradation model is proposed to improve both spatial and spectral quality of the synthetic images. Some ETM panchromatic and multispectral images are used to assess the new method. Its spatial and spectral effects are evaluated by qualitative and quantitative measures and the results are compared with those of IHS, PCA, Brovey, OWT(Orthogonal Wavelet Transform) and RWT (Redundant Wavelet Transform). The results show that the new method can keep almost the same spatial resolution as the panchromatic images, and the spectral effect of the new method is as good as those of waveletbased methods. 相似文献
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SHEN Wenbin NING Jinsheng 《地球空间信息科学学报》2007,10(1):4-11
The problem of separating gravitation from inertia is discussed in very general sense, and the conclusion is positive: man can separate gravitation from inertia, if various observation techniques are applied for. The accelerometer's position problem in satellite gravimetry is investigated, and the additional acceleration effect due to the position error of an instrument as well as the difference between the mass center and the gravity center is explored. 相似文献
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CHEN Junyong 《地球空间信息科学学报》2002,5(4):1-4
Urban geo-environment mainly concerns those regards in and around a city,such as the movement of earth crust and earth surface,conditions of hydrology,geology,geography and meteorology.The relevant studies on geo-disaster reduction and the influences resulted from human activities on the geo-environment are included as well.It is stressed in the paper that geo-environmental protection and management are of significance to the sustainable development for Chinese cities. 相似文献
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Tondozi Keto LIU Tianyou 《地球空间信息科学学报》2005,8(4):291-296
IntroductionGeophysics as its nameindicates has to do withthe physics of the earth and its surrounding at-mosphere . Gilbert’s discovery that the earth be-haves as a great and rather irregular magnet andNewton’s theory of gravitation may be said toconstitute the beginning of geophysics . Miningand the search of metals date from the earliestti mes , but the scientific record began with thepublicationin 1956 of the famous treatise De remetallica by Georgius Agricola , whichfor manyyears was … 相似文献
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小卫星由于其研发周期短、体积小、功能强、使用灵活等特点,在通信、遥感等领域得到越来越广泛的应用。在数字北京的建设中,将成为基础地理信息更新的重要手段,为实际应用提供新的途径。 相似文献
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P. F. Dale 《The Photogrammetric Record》1991,13(77):679-683
This paper was presented at the 1990 Thompson Symposium. It distinguishes between geographical information systems (GIS) as a set of hardware and software tools and the institutional problems that arise when implementing GIS in an organisational environment. It examines issues such as data quality, that arise when treating information as a corporate resource, as well as the legal, economic and social constraints on the use of data. 相似文献
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E. M. Sodano 《Journal of Geodesy》1967,41(3):233-236
Alternate formulas are given for the rigorous non-iterative solution of very long (as well as medium and very short) geodesics.
They are not only shorter and simpler than the author’s original version published in the Bulletin Géodésique, but the powers
of the spheroid parameter can be factored out in the same manner as in the corresponding solution of the Direct Geodetic Problem.
Theoretical, as well as practical, significance is noted. 相似文献
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从被动微波辐射计在轨辐射定标的角度出发, 选取亚马逊雨林作为高温地面目标, 利用DMSPF13-SSM/I数据和NCEP数据对研究区19—89GHz辐射特性进行分析。研究发现, 利用辐射亮温稳定的热带雨林作为地面目标, 对19—89GHz的频段, 微波辐射亮温计算精度可以达到1K以内; 对于6和10GHz这样的低频通道, 撒哈拉沙漠是一个可供选择的地面目标, 根据所建立的亮温计算模型, 利用数值预报分析场NCEP数据作为输入, 其亮温计算精度在2K以内。 相似文献
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志愿者地理信息数据大都依靠志愿者上传,数据质量未知,阻碍了志愿者地理信息的广泛应用,因此是志愿者地理信息首要解决的问题。本文分析了影响志愿者地理信息质量的相关因素和基于参考数据评价方法的相关研究成果,在此基础上提出了一种基于参考数据的志愿者地理信息质量评价方法,以最常见的数据完整性和数据精度作为质量评价的质量元素,详细论述了这两种质量元素的内涵。针对数据完整性评价,提出了与匹配相结合的几何数据完整性度量方法和基于属性项饱和度的属性数据完整性度量方法;针对几何数据精度评价,提出了基于变缓冲区的度量方法。然后给出了该评价方法的一般流程。最后,以深圳市Open Street Map数据为例,选取最新导航数据作为参考数据进行试验验证。实验结果表明,深圳市Open Street Map数据点要素完整性较差,但是线要素完整性与精度都非常高,可以作为基础地理信息的更新数据源。 相似文献
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城市交通网络面向对象的时空数据模型研究 总被引：3，自引：0，他引：3
原有的城市交通网络数据模型无法对大比例地图中道路的面状特征进行描述。本文引入面向对象的时空数据模型 ,把各种实体作为对象 ,把道路作为面状要素描述。作为面状要素的道路对象直接继承原有道路的非空间特征 ,通过道路中心线对象和交点对象来继承原有线状要素的道路特征 ,包括网络关系和叠加关系等 ,通过车道段对象来增加作为面状要素的道路特征 相似文献
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采用ArcGIS软件平台作为基础开发平台,以Windows系列平台为操作系统,以Visual Studio.NET(C#)为开发工具,应用Oracle数据库管理维护数据,构建3维地籍管理平台,实现地表、地上和地下土地使用权的有效管理,对地籍管理业务有重要意义。 相似文献
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针对高差对于地貌类型定义、不同地貌类型范围划定以及山地灾害危险性评价的重要意义,该文将坡脚的高程定义为基准高程,提出了动态窗口邻域统计的高差计算方法。计算每个栅格到坡脚的距离,作为该栅格的对应的窗口半径;利用邻域统计的方法,搜索该窗口范围内的最低高程值,即为坡脚的高程,作为该栅格高差计算的基准高程;最终通过高程值与基准高程相减运算,获取每个栅格点对应的高差。选取四川省都江堰市虹口地区为研究区,对比两种不同的高差计算方法。结果显示:在山脊和山肩部位,动态窗口计算的高差值大于静态窗口的高差值,而位于山脚动态窗口计算的高差值小于静态窗口计算的高差值;利用动态窗口获得的高差的精度明显高于静态窗口的计算结果,其平均偏差由75.53降低为13.24。 相似文献