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Vertical accuracy evaluation of freely available latest high-resolution(30 m)global digital elevation models over Cameroon(Central Africa)with gps/leveling ground control points.

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International Journal of Digital Earth 2019年第5期12卷 500-524页

作者： Loudi Yap Ludovic Houetchak Kande Robert Nouayou Joseph Kamguia Nasser Abdou Ngouh Marie Brigitte Makuate Research Laboratory in Geodesy National Institute of CartographyYaound3Cameroon Department of Physics Faculty of SciencesUniversity of Yaoundé1YaoundéCameroon

Digital Elevation Models(DEMs)contain topographic relief data that are vital for many geoscience *** study relies on the vertical accuracy of publicly available latest high-resolution(30 m)global DEMs over *** models are(1)the ALOS World 3D-30 m(AW3D30),(2)the Shuttle Radar Topography Mission 1 Arc-Second CBand Global DEM(SRTM 1)and(3)the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2(ASTER GDEM 2).After matching their coordinate systems and datums,the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global *** this,the three models are compared among them,in order to access random and systematic effects in the elevation data each of them ***,heights from 555 gps/leveling points distributed all over Cameroon are compared to each DEM,for their vertical accuracy *** and robust statistical measures,normality test,outlier detection and removal were used to describe the vertical quality of the *** test of the normality rejected the hypothesis of normal distribution for all tested global *** vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square(RMS)and Normalized Median Absolute Deviation(NMAD)are:AW3D30(13.06 m and 7.75 m),SRTM 1(13.25 m and 7.41 m)and ASTER GDEM 2(18.87 m and 13.30 m).Other accuracy measures(MED,68.3% quantile,95% quantile)supply some evidence of the good quality of AW3D30 over ***,the effect of land cover and slope on DEM vertical accuracy was also *** models have proved to be worse in the areas dominated by forests and shrubs *** 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated *** dependency of DEMs accuracy on the terrain roughness is *** all slope intervals,AW3D30 is performing

关键词： DEM AW3D30 SRTM 1 ASTER GDEM 2 Cameroon gps/leveling orthometric heights vertical accuracy

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结合gps/leveling和正高改正确定gps常年观测站正高

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测绘通报 2008年第3期 25-27页

作者：尹弘植黄鹤李东河成均馆大学校建设环境系统工学科

利用精密几何水准测量结合gps/leveling方法计算韩国行政自治部管辖内30所gps常年观测站天线基准点的正高。并联合进行对水准点和gps常年观测站偏心点的重力测量,使用正高改正方法计算出其改正量,提高正高的精确度。

关键词： gps常年观测站几何水准测量 gps/leveling 重力测量正高改正正高

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Results from a comprehensive gps Network: natural gas pipeline gps Network

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International Journal of Digital Earth 2013年第S2期6卷 67-80页

作者： O.Yildirim Faculty of Engineering and Natural Sciences Gaziosmanpas¸a UniversityTokatTurkey

Developing the Nabucco engineering infrastructure was the most challenging task imaginable and required state-of-the-art *** this purpose,a NabuccoGlobal Positioning System(gps)Network was *** is 762 km ***-hundred and two ground control unit points were *** order to provide the relationship with ITRF96 datum,it was surrounded by TFNGN(Turkish Fundamental National gps Network)and TNVCN(Turkish National Vertical Control Network)*** observations were evaluated in the form of a unique *** being reduced to projection segments,coordinates in ED50 datum were provided between datums by 2D-Helmert *** heights related to the gps Network were obtained by the improvement of TG-03 data based on a gps/leveling *** objective of the study is to present the results of a comprehensive engineering project which involved many geodetic considerations including gps,orthometric heights,and geoid undulations and gives insight into the accuracy and precision of such large projects in terms of recent geodetic *** this study,a Global Navigation Satellite System(GNSS)-based geodetic infrastructure is presented,methods to obtain the necessary precision requirements are provided,and experience is shared in order to provide an example of a large-scale pipeline project,and to provide insight into the planning necessary for future similar engineering projects.

关键词： ITRF96 ED50 datum gps/leveling accuracy

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gps-GRAVIMETRIC GEOID DETERMINATION IN EGYPT

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Geo-Spatial Information Science 2001年第1期4卷 19-23页

作者： Essam Ghanem gps Center Wuhan University Wuhan China

The main objective of this study is to improve the geoid by gps/leveling data in *** of the gravimetric geoid with gps/leveling data have been *** the basis of a gravimetric geoid fitted to gps/leveling by the least square method,a smoothed geoid was obtained.A high_resolution geoid in Egypt was computed with a 2.5′×2.5′ grid by combining the data set of 2 600 original point gravity values,30″×30″ resolution Digital Terrain Model (DTM) grid and the spherical harmonic model *** method of computation involved the strict evaluation of the Stokes integral with 1D_*** standard deviation of the difference between the gravimetric and the gps/leveling geoid heights is ±0.47 *** standard deviation after fitting of the gravimetric geoid to the gps/leveling points is better than ±13 *** the future we will try to improve our geoid results in Egypt by increasing the density of gravimetric coverage.

关键词： gravimetric geoid gps/leveling data fitting

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