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关于抵偿高程面与移动中央子午线最佳选取问题的研究 总被引:2,自引:0,他引:2
针对建立区域工程平面控制网为限制投影长度变形△S,经常采用的抵偿高程面法与移动中央子午线法最佳值确定的问题,提出应在∑△S^2=min的条件下确定,进而分析、推证出最佳抵偿高程面之高程或相对于测区平均高程面之高程的公式,最佳移动中央子午线横坐标的公式,并视大、小不同测区情报予以分析。 相似文献
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本文从理论和实际两方面讨论了局部三维网的平面坐标与高程坐标的精度,分析了平面坐标与高程坐标的相关性问题,并用一局部测边三维网,计算和分析了测边三角高程在什么情况下能代替等级水准测量。 相似文献
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针对建立区域工程平面控制网为限制投影长度变形ΔS ,经常采用的抵偿高程面法与移动中央子午线法最佳值确定的问题 ,提出应在∑ΔS2 =min的条件下确定 ,进而分析、推证出最佳抵偿高程面之高程或相对于测区平均高程面之高程的公式 ,最佳移动中央子午线横坐标的公式 ,并视大、小不同测区情况予以分析 相似文献
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采取平面网与高程网相结合的方法布设了施工控制网,并引用工程控制网优化设计的有关理论,结合实际对平面网的网形进行了机助优化.在网形确定的基础上,文中采用可靠因子为质量指标对网中的观测量进行优化,最终得到了满足精度和可靠性要求的最优布设方案. 相似文献
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欧洲GPS垂直参考网是为了统一欧洲不同的高程参考系统而设计的,在实践上和科学上的主要贡献是:-给出一个惟一的欧洲高程基准;-连接欧洲验潮站水准基点,监测海面绝对变化;-为确定欧洲大地水准面建立基准点,-为监测欧洲的地壳垂直运动网做准备。这个网由分布在整个欧洲的大约195个点组成,其中包括79个欧洲参考框架(EUREF)点,53个东欧和西欧的水准网结构点和63个验潮站,应用GPS于1997年5月21-29日观测,获得了在TERS89框架下的统一的大地高。 相似文献
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对中国高程控制网现代化工作的思考 总被引:1,自引:0,他引:1
随着空间和信息技术的快速发展,我国测绘基准中的国家高程控制网现代化也迫在眉睫。它应包括两个部分,一是国家高精度水准网,即mm级一等水准网的更新;二是具有cm级精度的(似)大地水准面的确定。建议切实执行《中华人民共和国测绘法》中"基础测绘成果应当定期更新,国民经济、国防建设和社会发展急需的基础测绘成果应当及时更新"的规定,尽快组织施测国家三期一等水准网,以保证国家高程控制网mm级高精度的可靠性和现势性。另一方面,应结合GPS水准和重力测量精化我国大陆的(似)大地水准面至cm量级,以利用GPS (似)大地水准面的技术求解相当于二、三等水准测量精度的正常高,这不仅可以改变传统高程测量的作业模式,节约人财物和时间,而且获得的点位高程的精度比较一致。在海岛、山区等困难或无法传递水准测量高程的地区,采用这一技术可以快捷地测得高程,其成果与国家高程基准、高程系统是统一的和协调的。 相似文献
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桥梁施工控制网的质量是工程施工总体质量的基础。探讨了GPS控制网的方案设计,精度确定及外业布设流程与方法。重点研究了GPS坐标基准的选择与确定,内业数据处理。针对高程数据异常拟合模型参数估计,提出了两步抗差估计GPS高程拟合方法,有效地保证了似大地水准拟合模型的可靠性。 相似文献
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针对高速铁路桥上CPⅢ控制网高程上桥测量特点,设计了一种精密三角高程上桥测量装置,削弱了大气折光误差对高程上桥测量精度的影响,免除了桥下过渡水准点的埋设,使三角高程上桥测量路线的选择更为灵活,前后视高差可实现同步、自动观测,测量精度和测量效率得到提高,该装置在哈大高铁桥梁CPⅢ控制网水准测量中取得了良好的应用效果。 相似文献
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陈月梅 《测绘与空间地理信息》2006,29(5):66-68
提出了在局部区域的椭球面上建立数字高程模型的原理和方法。这种椭球面的DEM是在区域性椭球面上基于新大地坐标系建立的,不同于现有的基于投影平面的DEM。由于未经过从椭球面到平面的投影,从而杜绝了投影变形,也消除了平面位置与水准高程之间作为3维坐标的不兼容性。在具体建模中,直接基于与测区平均高程面最优拟合的区域性椭球面,采用格网DEM的建模方法来建立椭球面DEM。 相似文献
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Summary In order to derive the ellipsoidal height of a point Pt, on the physical surface of the earth, and the direction of ellipsoidal normal through Pt, we presente here an iterative procedure rapidly convergent to compute, in a topocentric Cartesian system, the coordinates of Helmert's projection of the ground point Pt onto the reference ellipsoid of revolution .We derive as well the cofactor matrix of total vector of the topocentric coordinates of the above ground point and of its Helmert's projection so that to compute the variance of ellipsoidal height. 相似文献
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H. Fan 《Journal of Geodesy》1998,72(9):511-515
Historically, the mean Earth ellipsoid is obtained by fitting an ellipsoid of revolution to the geoid. Such an ellipsoid,
however, does not necessarily best fit the physical surface of the Earth due to the existence of topography outside the geoid.
In this paper, we present a purely geometrically defined Earth ellipsoid that best fits the physical surface of the Earth
so that the resulting ellipsoidal height attains minimum global mean square value. Using a global digital terrain model and
a global geopotential model, the size, shape and position of such an Earth ellipsoid have been numerically estimated.
Received: 6 September 1996 / Accepted: 1 April 1998 相似文献
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This paper generalizes the Stokes formula from the spherical boundary surface to the ellipsoidal boundary surface. The resulting
solution (ellipsoidal geoidal height), consisting of two parts, i.e. the spherical geoidal height N
0 evaluated from Stokes's formula and the ellipsoidal correction N
1, makes the relative geoidal height error decrease from O(e
2) to O(e
4), which can be neglected for most practical purposes. The ellipsoidal correction N
1 is expressed as a sum of an integral about the spherical geoidal height N
0 and a simple analytical function of N
0 and the first three geopotential coefficients. The kernel function in the integral has the same degree of singularity at
the origin as the original Stokes function. A brief comparison among this and other solutions shows that this solution is
more effective than the solutions of Molodensky et al. and Moritz and, when the evaluation of the ellipsoidal correction N
1 is done in an area where the spherical geoidal height N
0 has already been evaluated, it is also more effective than the solution of Martinec and Grafarend.
Received: 27 January 1999 / Accepted: 4 October 1999 相似文献
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大地测量应用卫星的轨道设计 ——椭球谐引力场下卫星的运动 总被引:1,自引:1,他引:0
本文首先注意到近球面包络进动轨道(近圆)是大地测量应用卫星的共有特征;接着指出地球引力位的等势面非常接近共焦椭球面,其主项是严格的共焦椭球面,次项是10-6的摄动项;最后得出,在共焦椭球面成层分布引力场下,存在一条特殊的轨道——椭球面包络进动轨道,位于椭球面上,沿着大地线(测地线)作匀速、变曲率、均匀进动(升交点西退或东进)运动;这样一条特殊的轨道,是几何大地测量学、物理大地测量学和空间大地测量学与轨道理论的完美结合;若用椭球面包络轨道代替近球面包络进动轨道,因其严格顾及J2项,将更有利于大地测量应用卫星的轨道设计、卫星群分布设计、覆盖计算、入轨控制等。 相似文献
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GPS测量所提供的高程为相对于WGS-84椭球的GPS大地高,而我国使用的是正常高。大地高等于正常高与高程异常之和,要使GPS高程在工程实际中得到应用,必须先求出高程异常,进而获得正常高。结合GPS测量和水准测量资料,用神经网络方法和二次多项式曲面拟合方法拟合高程异常,对拟合精度进行了分析比较,得出了有实用价值的结论。 相似文献
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Height datum unification between Shenzhen and Hong Kong using the solution of the linearized fixed-gravimetric boundary value problem 总被引:4,自引:0,他引:4
The paper proposes a new algorithm to unify height datums in different regions, which is based on the solution of the linearized
fixed-gravimetric boundary value problem. Compared with traditional methods, this method uses GPS ellipsoidal height and gravity
disturbances on the surface of the earth to obtain a quasigeoid, which is not related to any local vertical datums. As an
example, we calculate the height datum difference between Shenzhen and Hong Kong by applying this new method. The result shows
that the height difference obtained by this new method is consistent with the ground leveling result to a few centimeters. 相似文献
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针对EGM2008重力场模型辅助跨障碍GPS高程传递控制网布设方案进行研究,分别对GPS高程传递控制网进行不同点数的椭球高约束计算,将传递高程与实测高程进行比较,结果表明:跨越2~3 km的障碍GPS高程传递的精度能够达到0.010 m,GPS高程传递控制网中以约束一点椭球高为宜,增加椭球高约束个数并不能提高高程传递的精度。 相似文献
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Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data 总被引:1,自引:0,他引:1
Valérie Ballu Marie-Noelle Bouin Stéphane Calmant Eric Folcher Jean-Michel Bore Jérome Ammann Olivier Pot Michel Diament Bernard Pelletier 《Journal of Geodesy》2010,84(1):65-77
Knowledge of the position and motion of points on the seafloor can be critically important in both fundamental research (for
example, global geodesy and plate tectonics) and for more practical applications such as seismic risk evaluation, off-shore
construction and pipeline monitoring. In the Vanuatu subduction zone, for example, measuring deformation underwater could
provide valuable information for modeling deformation and understanding the seismic cycle. We report a shallow water experiment
in Vanuatu to measure the relative and absolute depth of seafloor points. The experiment differs from previous efforts mainly
in that it uses the height of the sea surface determined by kinematic GPS, allowing us to locate the points in a global reference
frame. The ITRF2005 ellipsoidal height of a seafloor benchmark was determined with a 1-sigma uncertainty of 0.7–2.1 cm. The
estimated ellipsoidal height differs only by a few tenths of a centimeter between measurements made in 2004 and another set
made in 2006. These results are encouraging and open new perspectives for vertical underwater deformation monitoring in shallow
water areas. Sea-surface GPS measurements can also help to reduce the uncertainty in depth difference determination for relative
measurements. 相似文献