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1.
由于空间大地测量和人卫大地测量的迅速发展,空间直角坐标与大地坐标之间的相互换算已成为一项重要课题。众所周知,解算大地坐标的经典方法是一种迭代法。近十年来,国内外发展了一些直接解算的新方法,以加快计算速度。然而这些方法都是近似的,其精度受到限制。本文导出的一种直接解算的闭合公式将能克服上述方法的缺点。 相似文献
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徐绍铨 《武汉大学学报(信息科学版)》1990,(1)
本文通过引入测站切面空间直角坐标系,导出用椭球面上弦线解算长距离大地测量主题正、反算精密公式。理论严密,公式封闭简单,宜于电算。为了便于实用,本文还扩展了相应的归算公式。 相似文献
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弦线法解算大地测量主题精密公式 总被引:2,自引:0,他引:2
徐绍铨 《武汉测绘科技大学学报》1990,15(1):19-27
本文通过引入测站切面空间直角坐标系,导出用椭球面上弦线解算长距离大地测量主题正、反算精密公式。理论严密,公式封闭简单,宜于电算。为了便于实用,本文还扩展了相应的归算公式。 相似文献
4.
高斯平均引数计算大地坐标主题反解的迭代算法 总被引:3,自引:0,他引:3
在地球椭球面上如果已知两点的大地经、纬度,求两点间的大地线长度及其正、反大地方位角的过程称为大地主题反解.大地主题计算在空间技术、航空、航海、国防等现代科学技术领域被广泛使用.高斯平均引数公式是解决中程大地主题计算的一种经典的方法.给出一种新的大地主题反解的方法,即迭代算法.这种算法是在正算公式的基础上进行的,形式简单,便于理解与编程,避免了枯燥的反解公式的推导. 相似文献
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超大规模大地网分区平差快速解算方法 总被引:8,自引:1,他引:8
针对超大规模大地网平差解算这一难题,首先按常规将大规模大地网分解成多个子网,并组成相应子网的误差方程和法方程,然后提出了用解算约化代替求逆约化的新算法,解算约化采用Cholesky分解法,计算过程中对联系误差方程进行压缩存储,并进行相应的有效算法。如此可大大节省大型大地网平差的计算时间,利用PentiumⅣ个人计算机即可解算全国范围的约5万个点(约18万个未知参数)的超大型大地网的整体平差问题,且计算时间只需3h左右。 相似文献
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大地主题问题的非迭代新解 总被引:7,自引:0,他引:7
首先对大地主题问题解算中的符号体系进行改进与统一,使之更符合大地测量的使用习惯;在此基础上讨论非迭代的大地主题问题的正反解,借助计算机代数系统Mathematica推导更准确的正解公式,得到非迭代的反解公式,与以往的解算相比该公式具有更简明的数学表达形式。该过程丰富和完善了大地主题问题的解算体系。最后进行正反解的数据验证。 相似文献
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M. S. Filmer C. W. Hughes P. L. Woodworth W. E. Featherstone R. J. Bingham 《Journal of Geodesy》2018,92(12):1413-1437
The direct method of vertical datum unification requires estimates of the ocean’s mean dynamic topography (MDT) at tide gauges, which can be sourced from either geodetic or oceanographic approaches. To assess the suitability of different types of MDT for this purpose, we evaluate 13 physics-based numerical ocean models and six MDTs computed from observed geodetic and/or ocean data at 32 tide gauges around the Australian coast. We focus on the viability of numerical ocean models for vertical datum unification, classifying the 13 ocean models used as either independent (do not contain assimilated geodetic data) or non-independent (do contain assimilated geodetic data). We find that the independent and non-independent ocean models deliver similar results. Maximum differences among ocean models and geodetic MDTs reach >150 mm at several Australian tide gauges and are considered anomalous at the 99% confidence level. These differences appear to be of geodetic origin, but without additional independent information, or formal error estimates for each model, some of these errors remain inseparable. Our results imply that some ocean models have standard deviations of differences with other MDTs (using geodetic and/or ocean observations) at Australian tide gauges, and with levelling between some Australian tide gauges, of \({\sim }\pm 50\,\hbox {mm}\). This indicates that they should be considered as an alternative to geodetic MDTs for the direct unification of vertical datums. They can also be used as diagnostics for errors in geodetic MDT in coastal zones, but the inseparability problem remains, where the error cannot be discriminated between the geoid model or altimeter-derived mean sea surface. 相似文献
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C. Kotsakis 《Journal of Geodesy》2013,87(7):661-673
The estimated coordinates from a minimum-constrained (MC) network adjustment are generally influenced by two different error sources, that is the data noise from the available measurements and the so-called datum noise due to random errors in the fiducial coordinates that are used for the datum definition with regard to an external reference frame. Although the latter source does not affect the estimable characteristics of a MC solution, it still contributes a datum-related noise to the estimated positions which reflects the uncertainty of the coordinate system itself for the adjusted network. The aim of this paper is to develop a new type of MCs which minimizes both of the aforementioned effects in the final coordinates of an adjusted network. This particular problem has not been treated in the geodetic literature and the solution which is presented herein offers an elegant unification of the classic inner constraints into a more general framework for the datum choice problem of network optimization theory. Furthermore, the findings of our study provide a useful and rigorous tool for frame densification problems by means of an optimal MC adjustment in geodetic networks. 相似文献
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L. A. Kivioja 《Journal of Geodesy》1971,45(1):55-63
By choosing sufficiently small elements of the length of the geodetic line, or of the latitude or longitude difference, the
other two can be computed at each element and the results can be accumulated to solve the problem with more than twenty significant
number accuracy if desired. Ten to twelve number accuracy was computed in the examples of this paper. The geodetic line elements
are kept in correct azimuth by Clairaut’s equation for the geodetic line. The computers can do millions of necessary computations
very economically in a few seconds. All other published methods solving the direct or indirect problem can be reliably checked
against results obtained by this method. The run of geodetic lines around the back side of the Ellipsoid is outlined. 相似文献
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空间直角坐标转换大地坐标的直接解法 总被引:1,自引:0,他引:1
根据地面点地心空间直角坐标与地心大地坐标的关系式,导出由空间直角坐标求解大地坐标的更为简洁的直接计算公式,并对计算误差进行分析讨论。理论分析和实际验算结果表明,该直接解法引起的纬度误差不大于10-5s,可以满足精密的大地测量需要。 相似文献
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贝赛尔大地主题解算是少数适合长距离大地主题计算的方法之一。文章通过对贝赛尔大地主题解算进行计算分析,发现贝赛尔大地主题反算中的大地线长计算精度受起点方位角的影响很大,误差可达8m。为了消去这一巨大误差,本文提出在大地主题反算时互换大地线起点和终点的方法,计算结果表明该方法可以有效消除方位角对大地线长误差的影响。 相似文献
17.
赵文光 《武汉大学学报(信息科学版)》1987,(2)
本文提出了一套以空间任意高度直线距离为边长的、高精度的中距离大地主题正算公式,省掉了投影归算过程,可以用卫星(气球)物理测距数据计算大地位置。 相似文献
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The source position time-series for many of the frequently observed radio sources in the NASA geodetic very long baseline
interferometry (VLBI) program show systematic linear and non-linear variations of as much as 0.5 mas (milli-arc-seconds) to
1.0 mas, due mainly to source structure changes. In standard terrestrial reference frame (TRF) geodetic solutions, it is a
common practice to only estimate a global source position for each source over the entire history of VLBI observing sessions.
If apparent source position variations are not modeled, they produce corresponding systematic variations in estimated Earth
orientation parameters (EOPs) at the level of 0.02–0.04 mas in nutation and 0.01–0.02 mas in polar motion. We examine the
stability of position time-series of the 107 radio sources in the current NASA geodetic source catalog since these sources
have relatively dense observing histories from which it is possible to detect systematic variations. We consider different
strategies for handling source instabilities where we (1) estimate the positions of unstable sources for each session they
are observed, or (2) estimate spline parameters or rate parameters for sources chosen to fit the specific variation seen in
the position-time series. We found that some strategies improve VLBI EOP accuracy by reducing the biases and weighted root
mean square differences between measurements from independent VLBI networks operating simultaneously. We discuss the problem
of identifying frequently observed unstable sources and how to identify new sources to replace these unstable sources in the
NASA VLBI geodetic source catalog. 相似文献
19.
Various formulations of the geodetic fixed and free boundary value problem are presented, depending upon the type of boundary data. For the free problem, boundary data of type astronomical latitude, astronomical longitude and a pair of the triplet potential, zero and first-order vertical gradient of gravity are presupposed. For the fixed problem, either the potential or gravity or the vertical gradient of gravity is assumed to be given on the boundary. The potential and its derivatives on the boundary surface are linearized with respect to a reference potential and a reference surface by Taylor expansion. The Eulerian and Lagrangean concepts of a perturbation theory of the nonlinear geodetic boundary value problem are reviewed. Finally the boundary value problems are solved by Hilbert space techniques leading to new generalized Stokes and Hotine functions. Reduced Stokes and Hotine functions are recommended for numerical reasons. For the case of a boundary surface representing the topography a base representation of the solution is achieved by solving an infinite dimensional system of equations. This system of equations is obtained by means of the product-sum-formula for scalar surface spherical harmonics with Wigner 3j-coefficients. 相似文献
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Various formulations of the geodetic fixed and free boundary value problem are presented, depending upon the type of boundary
data. For the free problem, boundary data of type astronomical latitude, astronomical longitude and a pair of the triplet
potential, zero and first-order vertical gradient of gravity are presupposed. For the fixed problem, either the potential
or gravity or the vertical gradient of gravity is assumed to be given on the boundary.
The potential and its derivatives on the boundary surface are linearized with respect to a reference potential and a reference
surface by Taylor expansion. The Eulerian and Lagrangean concepts of a perturbation theory of the nonlinear geodetic boundary
value problem are reviewed. Finally the boundary value problems are solved by Hilbert space techniques leading to new generalized
Stokes and Hotine functions. Reduced Stokes and Hotine functions are recommended for numerical reasons. For the case of a
boundary surface representing the topography a base representation of the solution is achieved by solving an infinite dimensional
system of equations. This system of equations is obtained by means of the product-sum-formula for scalar surface spherical
harmonics with Wigner 3j-coefficients. 相似文献