共查询到20条相似文献，搜索用时 109 毫秒
1.
给出了双星姿态测量的两种算法,并从几何和代数两个方面证实其存在双值问题;探讨了双值问题与精度衰减因子(DOP)之间的关系,并提出了双值问题的解决方案. 相似文献
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文章分析了测绘产品质量存在的问题及其成因，由此总结出测绘质量管理工作的两个方面，并对加强这两个方面的工作进行了深入探讨，最后提出建立测绘项目管理数据库，运用现代化手段保障测绘主管部门的质量监督管理。 相似文献
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用信息传输理论的观点看实施中的地图信息传输 总被引：3，自引：0，他引：3
本文用地图信息传输理论观点，从实施地图信息传输时不常引起重视的两个侧面出发，提出了影响传输效益的一些问题，并分析了根源。 相似文献
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等角投影有限元变换法研究 总被引：1，自引：0，他引：1
本文论证了任意两等角投影间的变换，可以归结为求拉普拉斯方程狄利克莱问题的解。并指出，一些著名等角投影变换的解析表达式，实际是狄利克莱问题在某种特殊条件下的精确解。但是，因为在大多数情形下求精确解是困难的，为此本文引进了求解狄利克莱问题的有限元法，并给出了应用有限元法进行等角投影变换的计算方法。最后通过实例评价了这一方法的精度。 相似文献
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GPS观测结果变形分析的参考框架及其合理性 总被引：8，自引：0，他引：8
参考框架问题是利用GPS观测资料得到位移场，进而分析地壳运动时必须解决的一个主要问题。本文对目前框架问题的两种主要处理方法作了归纳。指出这些方法的分析结果是否合理应予以定量判别。否则，将不能得出适当的位移解。对这两种方法所采用的参考框架的合理性给出了判别准则。并在此基础上，针对分析局部区域（例如中国大陆）的相对运动的需要提出一种较为容易实现的局部相对稳定参考框架。介绍了这种方法的具体做法。并通过对攀登计划下的两期复测资料，用这3种做法做了试算和验证。 相似文献
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ＬＯＧ算子是边缘提取中一种常用算法，着重讨论了应用此种方法进行边缘撮所存在的两个问题，并探讨了解决的方法。 相似文献
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图像平滑与边缘检测的迭代算法 总被引：2，自引：0，他引：2
图像平滑和边缘检测是图像处理、计算机视觉等领域研究的经典问题。区别以往对这两个问题独立求解的做法，文中作者将图像平滑与边缘检测问题结合起来综合考虑。首先，提出了基于全局边缘特征的边缘检测算法并对自适应平滑算法进行了改进。然后，利用迭代处理的思想对图像进行平滑和边缘检测，得到了迭代的平滑与边缘检测算法。实验表明，该算法可以有效地解决平滑过程中的细节保持和边缘检测时剔除伪边缘这两个难题。 相似文献
10.
利用局部重力数据改进重力场模型 总被引：4，自引：2，他引：4
本文系统论述了利用局部重力数据对已知重力场模型位系数加以改进的理论和方法，问题的实质是重力异常和位系数两类数据的综合利用，文中给出了联合平差和局部积分改进两种方法，重点讨论了局部积分改进的位系数改正数的谱权综合法，并给出了数值试验结果。 相似文献
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提出了Poisson重力边值问题,即关于扰动位的Poisson方程的Stokes问题和Neumann问题。作为导引,先研究Poisson方程的Dirichlet问题．再分别引入一种辅助函数,将Stokes问题和Neumann问题改化为Dirichlet问题,从而立即得到它们的积分解。最终解式表现为两部分叠加：一部分仅与边界观测相关,另一部分为对地形测量的响应,为研究地形测量对外部重力场和大地水准面的精化提供新的途径。 相似文献
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In the linear estimation problem associated with an experiment that is exactly repeated a number of times, the estimation
parameters may naturally be partitioned into two groups, those that are common to all repetitions, and those that are particular
to each repeat experiment. We derive least-squares solutions that minimise in norm either group of parameters, as also the
trace of the corresponding covariance matrix. These solutions are applied to the station adjustment of triangulation surveying,
and to the estimation problem of satellite radar altimetry: to estimate simultaneously mean sea surface heights and residual
radial orbit errors, while minimising the norm of either group of parameters. This altimetry problem is considered in the
cases of collinear, local crossover and global crossover data.
Received: 6 January 1997 / Accepted: 21 December 1998 相似文献
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地球物理反问题中两种正则化方法的比较 总被引：4，自引：0，他引：4
通过对最小二乘法的改造引入了两种正则化方法及其解的表达式，从理论上阐述了Tikhonov与TS—VD两种正则化方法效果的差异，特别就病态方程组在三种情况——系数阵良定秩、系数阵劣定秩右端项劣衰减、系数阵劣定秩右端项良衰减下正则化方法的应用效果作了比较．并给出了数值例子。 相似文献
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Exploring the Solution Space of Semi-structured Geographical Problems Using Genetic Algorithms 总被引：1，自引：0，他引：1
Semi-structured geographical problems are often addressed by groups of decision-makers. Each group member is likely to have a specific set of objectives that they wish to address and a unique perspective on the way in which the problem should be solved. The solution to such problems often requires consensus building and compromise among decision-makers as they attempt to optimize their own criteria. The set of criteria adopted by a particular decision-maker constrains the set of solutions he/she will deem acceptable. Compromise among multiple decision-makers can occur at the intersection of these constrained solution sets. Knowledge about the criteria space, the solution space, and the relation between the two is often incomplete for semi-structured problems. New tools are needed to explore, analyze, and visualize the solution space of a problem with respect to multiple analytical models and criteria. In this research we explore the utility of genetic algorithms as an effective means to: (1) search the solution space of geographical problems; (2) visualize the spatial ramifications of alternative criteria spaces; and (3) identify compromise solutions. 相似文献
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The idea of transforming the geodetic boundary value problem into a boundary value problem with a fixed boundary dates back
to the 1970s of the last century. This transformation was found by F. Sanso and was named as gravity-space transformation. Unfortunately, the advantage of having a fixed boundary for the transformed problem was counterbalanced by
the theoretical as well as practical disadvantage of a singularity at the origin. In the present paper two more versions of
a gravity-space transformation are investigated, where none of them has a singularity. In both cases the transformed differential
equations are nonlinear. Therefore, a special emphasis is laid on the linearized problems and their relationships to the simple
Hotine-problem and to the symmetries between both formulations. Finally, in numerical simulation study the accuracy of the
solutions of both linearized problems is studied and factors limiting this accuracy are identified. 相似文献
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航空重力测量数据向下解析延拓通常是一个病态方程的求解问题,从空中延拓到地面上的重力异常数据因受病态干扰质量不等。把其中质量较差的部分挑选出来,然后再进行有针对性的处理,这种做法的好处是尽量减少对于质量较好数据的破坏,以保持其原有的完好性。提出了两种破损点修复的方法:一是部分岭估计,可在不增加任何新观测的情况下实施;二是部分贝叶斯估计,利用已有的地面数据对破损点做有节制的修复。两种方法均具有较强的可操作性。 相似文献
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P4P is the pseudo-ranging 4-point problem as it appears as the basic configuration of satellite positioning with pseudo-ranges
as observables. In order to determine the ground receiver/satellite receiver (LEO networks) position from four positions of
satellite transmitters given, a system of four nonlinear (algebraic) equations has to be solved. The solution point is the
intersection of four spherical cones if the ground receiver/satellite receiver clock bias is implemented as an unknown. Here
we determine the critical configuration manifold (Determinantal Loci, Inverse Function Theorem, Jacobi map) where no solution
of P4P exists. Four examples demonstrate the critical linear manifold. The algorithm GS solves in a closed form P4P in a manner
similar to Groebner bases: The algebraic nonlinear observational equations are reduced in the forward step to one quadratic
equation in the clock bias unknown. In the backward step two solutions of the position unknowns are generated in closed form.
Prior information in P4P has to be implemented in order to decide which solution is acceptable. Finally, the main target of
our contribution is formulated: Can we identify a special configuration of satellite transmitters and ground receiver/satellite
receiver where the two solutions are reduced to one. A special geometric analysis of the discriminant solves this problem.
? 2002 Wiley Periodicals, Inc. 相似文献
20.
Béla Paláncz Joseph L. Awange Piroska Zaletnyik Robert H. Lewis 《Journal of Geodesy》2010,84(1):79-95
A fundamental task in geodesy is solving systems of equations. Many geodetic problems are represented as systems of multivariate
polynomials. A common problem in solving such systems is improper initial starting values for iterative methods, leading to
convergence to solutions with no physical meaning, or to convergence that requires global methods. Though symbolic methods
such as Groebner bases or resultants have been shown to be very efficient, i.e., providing solutions for determined systems
such as 3-point problem of 3D affine transformation, the symbolic algebra can be very time consuming, even with special Computer
Algebra Systems (CAS). This study proposes the Linear Homotopy method that can be implemented easily in high-level computer languages like C++ and Fortran that are faster than CAS by at
least two orders of magnitude. Using Mathematica, the power of Homotopy is demonstrated in solving three nonlinear geodetic problems: resection, GPS positioning, and affine
transformation. The method enlarging the domain of convergence is found to be efficient, less sensitive to rounding of numbers,
and has lower complexity compared to other local methods like Newton–Raphson. 相似文献