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1.
Least-squares by observation equations is applied to the solution of geodetic boundary value problems (g.b.v.p.). The procedure is explained solving the vectorial Stokes problem in spherical and constant radius approximation. The results
are Stokes and Vening-Meinesz integrals and, in addition, the respective a posteriori variance-covariances.
Employing the same procedure the overdeterminedg.b.v.p. has been solved for observable functions potential, scalar gravity, astronomical latitude and longitude, gravity gradients
Гxz, Гyz, and Гzz and three-dimensional geocentric positions. The solutions of a large variety of uniquely and overdeterminedg.b.v.p.'s can be obtained from it by specializing weights. Interesting is that the anomalous potential can be determined—up to a
constant—from astronomical latitude and longitude in combination with either {Гxz,Гyz} or horizontal coordinate corrections Δx and Δy, or both. Dual to the formulation in terms of observation equations the overdeterminedg.b.v.p.'s can as well be solved by condition equations.
Constant radius approximation can be overcome in an iterative approach. For the Stokes problem this results in the solution
of the “simple” Molodenskii problem. Finally defining an error covariance model with a Krarup-type kernel first results were
obtained for a posteriori variance-covariance and reliability analysis. 相似文献
2.
Summary According to the plate tectonic theory of Le Pichon [1968] we summarized the absolute values of the angular rate of rotation
of the Eurasia and America plates determined by astronomical latitude observations. The authors then tried to use the data
of longitude observation so far available to emphasize the existence of similar crust movements. The analysis of longitude
data has shown the minor homogeneity of these astronomical observations especially as far as the observations obtained by
means of PZT are concerned. By using particularly accurate observational data [Torao & Okasahi, 1965, 1969] the data of longitude
variations confirm the existence of movements in the earth’s crust, exactly equal to those deduced by the analysis of latitude
observations and in agreement with the results of geophysical measurements. 相似文献
3.
The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local
gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential.
The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem
of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector
(from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation
Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference
benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity
field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived
gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential
difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred
into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of
the offset of the zero point of the Iranian height datum from the geoid’s potential value W
0=62636855.8 m2/s2. According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid. 相似文献
4.
新天文常数、系统对天文经纬度和方位角的影响 总被引：1，自引：0，他引：1
本文从理论上讨论了新天文常数、系统对恒星视位置影响的周期性、计算公式及其数值范围,并结合一等天文外业的实际情况,推导了新天文常数、系统对天文经纬度和方位角的影响公式及其数值范围,从而得出在任何年观测都可以使其影响忽略不计等结论。 相似文献
5.
L. A. Kivioja 《Journal of Geodesy》1969,43(3):263-275
A small area of a mirror can be made vertical with a high degree of accuracy by using a free mercury surface and an autocollimation
target made of a mirror. The direction of the horizontal axis of a theodolite can be established, made and kept perpendicular
to the vertical mirror for all telescope altitudes and the direction of the line of sight can be made, perpendicular to the
horizontal axis with the same high degree of accuracy. Observations can thus be made on any part of a chosen celestial vertical
circle much more accurately than by using the best striding levels. This application is potentially useful in determination
of: astronomical longitude; changes in longitude differences with time, or the possible East-West component of continental
drift; right ascension differences between stars; and the rotation rate of the Earth. Other applications include a leveling
instrument of a new type, checking of tubular spirit levels, monitoring tidal variations in the direction of the plumb line,
establishing an accurate 90° angle, and checking the graduations of the horizontal and vertical circles of theodolites. The
impersonal micrometer for special astronomical observations stops the star image. Only parallel rays will enter the telescope
when the observer is tracking the star keeping the star image stationary at the center of cross hairs. 相似文献
6.
Summary The discrepancy between precision and accuracy in astronomical determinations is usually explained in two ways: on the one
hand by ostensible large refraction anomalies and on the other hand by variable instrumental errors which are systematic over
a certain interval of time and which are mainly influenced by temperature.In view of the research of several other persons and the author’s own investigations, the authors are of the opinion that
the large night-errors of astronomical determinations are caused by variable, systematic instrumental errors dependent on
temperature. The influence of refraction anomalies is estimated to be smaller than 0″.1 for most of the field stations.
The possibility of determining the anomalous refraction from the observations by the programme given by Prof. Pavlov and Anderson
has also been investigated. The precision of the determination of the anomalous refraction is good as long as no other systematic
error working in a similar way is present.The results, which are interpreted as an effect of the anomalous refraction by Pavlov and Sergijenko, could also be interpreted
as a systematic instrumental error.
It is furthermore maintained thatthe latitude and longitude of a field station can be determined in a few hours of one night if the premisses given in [3, p.68]are kept.
It has been deplored that the determination of the azimuth has not been given the necessary attention. It is therefore proposed
to intensify the research on this problem.
The profession has been called upon to acquaint itself better with the valuable possibilities of astronomical determinations
and to apply them in a useful and appropriate manner. At the same time, attention has been called to the possibility of improving
astronomical determinations with regard to accuracy as well as effectiveness. 相似文献
7.
The secular latitude variations of the five ILS stations of Mizusawa, Kitab, Carloforte, Gaithersburg and Ukiah were analyzed
taking into account the recent continental drift theory. Using Le Pichon's 1968 reconstruction, the rate of rotation was computed
from the astronomical data, fixing the pole of rotation by Le Pichon's determination. The most reasonable solution was obtained
considering Mizusawa, Kitab and Carloforte lying on the Eurasia plate, the two American stations as one on the American plate
(Gaithersburg) and the other on the North—East Pacific plate (Ukiah). The resulting relative rate between the Euro-American
plates is found to be 0".0028/year and between the American—Pacific plates 0".0032/ years, or about 1°,3/106 years and in excellent agreement with the plate tectonic theory.
Luxembourg Meeting of the “Journées Luxembourgeoises de Géodynamique”, 1972. 相似文献
8.
《测量评论》2013,45(74):175-181
AbstractIn an article in the Review of October 1938, iv, 30,450-457, under the heading “Geographical Positions in Malaya and Siam”, Mr. A. G. Bazley gives a comparison of the Indian and Siamese, and Siamese and Malaya, triangulations at common points and discusses the possibility of an error in the longitude of the datum of the Malayan system. In the Review of April, 1939, v, 32, 112-113, he has elaborated certain points, and remarks in connection with the doubt in the longitude of the Malayan datum that connection of the F.M.S. network with that of Siam and India, and some more latitude and longitude observations by the F.M.S. Survey, are essential to a satisfactory solution of this rather involved problem. Since the above article was written, a lot more infornlation has become available about the Indo-Siamese triangulation connections and a firm connection between the triangulations of Sianl and Malaya has been established in 1946. It is hoped that a review of the present position would be of interest, especially as the various links effected open up a definite possibility of a continuous chain of triangulation from India to Australia. 相似文献
9.
全球导航卫星系统（GNSS）参考网多用于估计卫星轨道/钟差、监测地表形变和速度场、确定精密地球自转参数等方面。相关数据处理模式包括：双差基线解（DD）和非差精密单点定位（PPP）等。本文首先从GNSS基本观测方程出发,通过选取两组基准参数,导出了上述两模式下的列满秩观测方程,然后分析了它们的不足,例如：相位偏差在DD模式中吸收了钟差,丧失了时不变特性;模糊度在PPP模式中吸收了相位偏差,失去了整数性。基于上述分析,本文提出了一种新的参考网数据处理方案,以充分融合DD和PPP模式的优势。它的关键策略是精选基准参数,以达到消秩亏的目的,具体优点体现在：相位偏差独立可估,若合理约束为时不变参数,可充分减少参数个数,提高网解精度;待估模糊度具备整周特性,经由模糊度固定,可改善网解可靠性。 相似文献
10.
《测量评论》2013,45(65):131-134
Abstract1. In geodetic work a ‘Laplace Point’ connotes a place where both longitude and azimuth have been observed astronomically. Geodetic surveys emanate from an “origin” O, whose coordinates are derived from astronomical observations: and positions of any other points embraced by the survey can be calculated on the basis of an assumed figure of reference which in practice is a spheroid formed by the revolution of an ellipse about its minor axis. The coordinates (latitude = ?, longitude = λ and azimuth = A) so computed are designated “geodetic”. 相似文献
11.
12.
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
13.
A. M. C. Srivastava 《Journal of Geodesy》1984,58(4):510-517
The astrogeodetic—gravimetric method based on the principle of least—squares solution has been used to determine the geocentric
Indian geodetic datum making use of the available nongeocentric astrogeodetic data and the gravimetric geocentric geoidal
heights in the form of smoothened values. Everett's method of interpolation has been used to obtain the smoothened geoidal
heights at the astrogeodetic stations in India from the available generalized values at 1°×1° corners. The values of the geoidal
height and deflections of the vertical at the geodetic datum Kalianpur H.S. so obtained have the negligible difference from
the values computed earlier by the same method using directly computed gravimetric geoidal heights at the astrogeodetic stations,
indicating that the use of the interpolated values in the astrogeodetic—gravimetric method employed would be an economical
approach of absolute orientation of a nongeocentric system if the gravimetric geoidal heights are available at 1°×1° corners
in the area of interest. 相似文献
14.
H. M. Dufour 《Journal of Geodesy》1968,42(2):125-143
Resume Après de nombreuses années d’hésitation, on a finalement reconnu, au Congrès de Florence, en 1955, que dans le repérage des
altitudes, seule la notion depotentiel était claire et sans ambigu?té, l’altitude au sens courant du terme étant conventionnelle.
De la même fa?on, pour le repérage géométrique des points à la surface de la Terre, les coordonnées (X Y Z) des points, dans letrièdre cartésien terrestre général, sont les inconnues fondamentales; les coordonnées géodésiques couramment utilisées (longitude, latitude altitude
H au-dessus de l’ellipso?de) sont conventionnelles. Mais pratiquement, afin d’écrire commodément les relations d’observation,
il para?t intéressant de passer par l’intermédiaire detrièdres locaux (trièdres laplaciens), liés de fa?on invariable au système cartésien général, et de repérer toutes les grandeurs dans ces
trièdres locaux.
Toutes les observations utilisées en Géodésie s’expriment de fa?on simple et sans singularités dans ces trièdres locaux. La
jonction des triangulations classiques, l’Astrogéodésie, la synthèse des Géodésies classique et spatiale sont facilitées.
En astronomie de position, les grandeurs longitude, latitude, azimut, sont avantageusement remplacées par: déviation Est-Ouest,
déviation Nord-Sud, azimut de Laplace. Les relations d’observation s’écrivent sans difficulté, même dans les régions polaires.
L’application pratique des nouvelles formules obtenues a été réalisée avec succès par L.F. Gregerson (Service Géodésique du
Canada).
Summary At Florence, in 1955, it was accepted that, in the problems of levelling, the notion ofpotential was scientifically clear, and that the altitude could derive from it only through a conventional process. In the same manner, when we want to have a geometric reference of the points at the earth surface, we use the coordinates (X Y Z) in thegeneral cartesian trihedron as fundamental unknowns, the geodetic coordinates (λϕH) deriving from (X Y Z) through a conventional process. Practically, in order to set up the observation equations, it is necessary to define local trihedrons (laplacian trihedrons), deriving from the cartesian general system through a fixed transformation, and to refer all the unknowns in these local trihedrons. All the observations used in Geodesy can be expressed simply and without any singularity in these local trihedrons. The links between classical geodetic nets, the astrogeodesy, the combination between classical and spatial geodesy, become easier. In astronomical controls, “longitude, latitude, azimut” must be replaced by: W-E deflection, N-S deflection and Laplace azimuth. Thus all the observation equations can be set, even in polar regions. A practical application of the new formulae was done successfully by L.F. Gregerson (Geodetic Survey of Canada).相似文献
15.
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
16.
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
17.
在利用数字天顶摄像仪通过天文测量确定天文垂线偏差的工作中,要求对CCD数字图像中星象中心进行亚像素定位。本文利用MATLAB实现对FITS格式CCD天文图像的正常读取,并与FV读取结果比较分析。在已有亚像素定位的修正矩方法基础上,提出一种利用迭代法寻求合适门限对二维修正矩方法进行改善。利用MATLAB实现对实测图像数据的处理与分析,探讨门限的取值对不同星等恒星定位精度的影响,给出门限的最佳取值。通过与已有修正矩算法处理结果比较分析,在以往修正矩方法计算基础上改进计算区域后再用迭代法计算,暗星定位精度有了很大提高。 相似文献
18.
19.
Present day inertial surveys are limited to single traverse runs in which the number of unknown system parameters to be determined
are few, depending on the number of control points available along the traverse. Further, conventional inertial surveys are
generally restricted to the determination of coordinates with no possibility for a rigorous post-mission adjustment of the
observations. The consequence is the continued presence of systematic trends in the residuals, even after the use of error
models such as those proposed by Ball, Gregerson or Kouba. Future work aiming at higher accuracies obviously requires more
comprehensive models and rigorous adjustment procedures. These can be accomplished by the development of such error models
and by the use of “area surveys”, instead of the single traverses, together with rigorous adjustment procedures suitable for
the network of criss-crossing lines inertially surveyed. In such a network the cross-over points serve as constraints for
the geodetic parameters (latitude, longitude, height, gravity anomaly, deflection components) and allow the addition of hardware
and software related error parameters. Thus an opportunity is provided to effectively self-calibrate the system—a concept
successfully used, for example, in photogrammetry or in satellite tracking. The number and the strength of such parameters
depend on the number of control and cross-over points. The adjustment, of course, also provides the necessary statistical
information on the adjusted parameters, such as their precision and the correlation between them.
The presentation will describe current work at OSU in this area.
Presented at the Second International Symposium on Inertial Technology for Surveying and Geodesy, Banff, Canada, June 1–5,
1981. 相似文献
20.
G. Blaha 《Journal of Geodesy》1978,52(3):191-198
The radial distance (length of a position vector) from the geocenter to the geoid as defined by the spherical harmonic potential
coefficients is needed e.g. in the process of adjusting satellite altimeter data. The geocentric latitude and longitude associated
with this distance are assumed known—in this case derived from satellite altimetry. Typically, the radial distance can be
computed to a desired accuracy in an iterative process. Even if a crude initial value is adopted, a sub-meter accuracy is
achieved on the second iteration, while the third iteration yields a sub-millimeter accuracy. If the best possible initial
value is taken, such as the radial distance to the mean earth ellipsoid, the iterative process may be accelerated by one iteration.
But even then two iterations will be needed in most cases. However, an algorithm has been designed that yields excellent results,
characterized by a sub-centimeter accuracy, already from the first iteration. It results in important computer savings, considering
that in real data reductions of satellite altimetry, the radial distance needs to be computed at thousands of locations. 相似文献