共查询到20条相似文献，搜索用时 31 毫秒
1.
构建了一个纬线表象为平行于赤道的直线,经线表象为对称于中央直经线的双曲线,且面积没有变形的投影集合,并得到一组概括公式。该公式不仅包括了克拉斯特创建的经线交于极点的双曲经线等面积伪圆柱投影,而且也包括了经线交于极线的双曲经线等面积伪圆柱投影。 相似文献
2.
地图投影计算机代数分析研究进展 总被引：1，自引：0，他引：1
地图投影是现代地图学的重要组成部分,涉及大量的椭圆函数幂级数展开、隐函数复合函数微分、椭圆积分、复变函数运算等一系列烦琐的数学分析过程,人工推导不但费时费力,而且容易出错,有时由于难以忍受的复杂性等各种原因,甚至根本无法实现。本文主要从椭球各纬度间正反解符号表达式、不同变形性质地图投影间的直接变换、高斯投影的复变函数表示、斜轴墨卡托投影数学分析、极区海图投影及变换等5个方面,论述了地图投影计算机代数分析取得的研究进展,讨论了该领域有待进一步解决的主要问题,对推动地图投影学的发展具有积极意义。 相似文献
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4.
刘大海 《测绘科学技术学报》2012,(1):9-11
高斯投影复变换的数值计算简单快捷,具有重要的工程应用价值.从数值计算角度出发,使用计算机代数系统Mathcad,Matlab以及Mathematica对高斯投影复变换进行了改进:只需建立正算变换计算式而不再需要建立反算变换计算式.对于复方程,利用系统的求根函数直接求解.对于复积分,研究了积分级数分析法、椭圆积分函数法及... 相似文献
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超大视场太阳敏感器图像质心提取算法 总被引：3，自引：0，他引：3
太阳图像质心提取是利用太阳敏感器进行天文导航的关键技术之一,直接决定了太阳敏感器的观测精度。针对超大视场太阳敏感器非圆形太阳图像质心提取问题,首先提出像面椭圆拟合算法,较好地解决了椭圆及近似椭圆形太阳图像的质心提取问题,然后进一步提出了球面圆拟合算法。该算法根据相机的投影和畸变模型,将太阳图像的边缘点映射到物方空间,对物方空间的边缘点进行球面圆拟合,从而确定太阳质心位置。在估计球面圆拟合算法的精度时,需要将太阳质心位置映射回像面。理论上,球面圆拟合算法不再需要顾及太阳图像的形状,算法更为严谨。将椭圆拟合算法和球面圆拟合算法应用到实测的太阳图像质心提取中。结果表明,椭圆拟合算法更适合处理半视场角70°~80.3°的太阳图像,平均精度约为0.075pixels;球面圆拟合算法更适合处理半视场角大于80.3°的太阳图像,平均精度约为0.082pixels。 相似文献
6.
An operational algorithm for computation of terrain correction (or local gravity field modeling) based on application of closed-form solution of the Newton integral in terms of Cartesian coordinates in multi-cylindrical equal-area map projection of the reference ellipsoid is presented. Multi-cylindrical equal-area map projection of the reference ellipsoid has been derived and is described in detail for the first time. Ellipsoidal mass elements with various sizes on the surface of the reference ellipsoid are selected and the gravitational potential and vector of gravitational intensity (i.e. gravitational acceleration) of the mass elements are computed via numerical solution of the Newton integral in terms of geodetic coordinates {,,h}. Four base- edge points of the ellipsoidal mass elements are transformed into a multi-cylindrical equal-area map projection surface to build Cartesian mass elements by associating the height of the corresponding ellipsoidal mass elements to the transformed area elements. Using the closed-form solution of the Newton integral in terms of Cartesian coordinates, the gravitational potential and vector of gravitational intensity of the transformed Cartesian mass elements are computed and compared with those of the numerical solution of the Newton integral for the ellipsoidal mass elements in terms of geodetic coordinates. Numerical tests indicate that the difference between the two computations, i.e. numerical solution of the Newton integral for ellipsoidal mass elements in terms of geodetic coordinates and closed-form solution of the Newton integral in terms of Cartesian coordinates, in a multi-cylindrical equal-area map projection, is less than 1.6×10–8 m2/s2 for a mass element with a cross section area of 10×10 m and a height of 10,000 m. For a mass element with a cross section area of 1×1 km and a height of 10,000 m the difference is less than 1.5×10–4m2/s2. Since 1.5× 10–4 m2/s2 is equivalent to 1.5×10–5m in the vertical direction, it can be concluded that a method for terrain correction (or local gravity field modeling) based on closed-form solution of the Newton integral in terms of Cartesian coordinates of a multi-cylindrical equal-area map projection of the reference ellipsoid has been developed which has the accuracy of terrain correction (or local gravity field modeling) based on the Newton integral in terms of ellipsoidal coordinates.Acknowledgments. This research has been financially supported by the University of Tehran based on grant number 621/4/859. This support is gratefully acknowledged. The authors are also grateful for the comments and corrections made to the initial version of the paper by Dr. S. Petrovic from GFZ Potsdam and the other two anonymous reviewers. Their comments helped to improve the structure of the paper significantly. 相似文献
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一种新的INSAR干涉条纹图滤波方法 总被引：6，自引：0，他引：6
干涉条纹图滤波是合成孔径雷达干涉测量处理中不可缺少的重要环节.对干涉条纹图滤波的一个重要要求是在有效抑制噪声的同时尽可能地保持条纹的跳变纹理信息.在分析干涉条纹图一阶差分的分布性质和三种当前最常用干涉条纹图滤波的算法的优缺点的基础上,提出基于椭圆方程的干涉条纹方向检测方法,并基于此推导了基于误差方程的用于表述不同方向的像素与滤波窗口中心像素的相关关系的加权模型,以此加权模型修正窗口均值滤波和圆周期均值滤波,得到新的保边缘的滤波器.接着分析了新滤波器的计算复杂度和不同权函数对滤波结果的影响.以此新的椭圆加权的保边缘滤波器处理了河北尚义地区的ERS-1/2合成孔径雷达数据,证明了本文提出的新滤波算法具有噪声抑制效果好,边缘信息保持能力强,计算速度快和可灵活配置等优点. 相似文献
8.
提出利用三维激光扫描点云截取隧道横断面拟合椭圆进行形变监测的方法。方法分为隧道中轴线提取,连续断面截取和椭圆拟合。隧道中轴线通过点云在水平面上投影后搜索的上下边缘点分别拟合二次曲线求均值得到;沿隧道中轴线设定等距间隔点,在间隔点处以中轴线正交方向截取断面;对截取的断面拟合椭圆并与设计值比较进行形变分析。实验表明,方法可以充分利用点云的大数据量特征,获得隧道内任意处的断面,是对目前监测方式的有益补充。 相似文献
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The concept of SOM was originated by Colvocoresses, which was mathematically developed and later modified by Snyder. It is most suitable for continuous mapping of satellite imagery, true to scale along ground track. Simplified mathematical formulation without complicated integral equations and constants of SOM projection for Landsat, SPOT and IRS satellites on Clarke and Everest spheroids are presented in this paper for ease of calculations. 相似文献
10.
The upward-downward continuation of a harmonic function like the gravitational potential is conventionally based on the direct-inverse
Abel-Poisson integral with respect to a sphere of reference. Here we aim at an error estimation of the “planar approximation”
of the Abel-Poisson kernel, which is often used due to its convolution form. Such a convolution form is a prerequisite to
applying fast Fourier transformation techniques. By means of an oblique azimuthal map projection / projection onto the local
tangent plane at an evaluation point of the reference sphere of type “equiareal” we arrive at a rigorous transformation of
the Abel-Poisson kernel/Abel-Poisson integral in a convolution form. As soon as we expand the “equiareal” Abel-Poisson kernel/Abel-Poisson
integral we gain the “planar approximation”. The differences between the exact Abel-Poisson kernel of type “equiareal” and
the “planar approximation” are plotted and tabulated. Six configurations are studied in detail in order to document the error
budget, which varies from 0.1% for points at a spherical height H=10km above the terrestrial reference sphere up to 98% for points at a spherical height H = 6.3×106km.
Received: 18 March 1997 / Accepted: 19 January 1998 相似文献
11.
本文着重讨论了保持地球上某一条特定曲线等长的等角投影的存在性特点和数学模型,并在此基础上首次求出了保持等角航线等长的等角投影和斜椭圆柱等角投影。本文所述的理论和方法可做为建立等角空间投影的基础。 相似文献
12.
《制图学和地理信息科学》2013,40(2):79-88
The Robinson projection is one of the most preferred projections for world reference maps in atlas cartography. The projection is constructed from Robinson's look-up table since there are no analytical formulas. This deficiency has led to a number of requests for the plotting formulas to which cartographers have responded by deriving analytical equations using different interpolation algorithms applied to Robinson's table values. The Robinson projection was examined with regard to its deformations calculated by four different algorithms, including the multiquadratic method. The numerical evaluations were then used to compare the algorithms. Solutions have been presented including some criticisms about this projection. The latitudes along which the scale is true and on which the maximum angular distortion equals zero have been determined. 相似文献
13.
The work of a recent Soviet geodetic surveying expedition to the Central Arctic and the Barents Sea off Franz Josef Land is described, with an emphasis on gravimetric surveying and determination of gravimetric control points at the North Pole and at two drifting polar research stations. In addition, glacier fields of Alexander Land (Franz Josef Land) were mapped and keys for their interpretation on space imagery identified. Translated from: Geodeziya i kartografiya, 1988, No. 3, pp. 9-12. 相似文献
14.
《测量评论》2013,45(32):85-89
AbstractThe necessity of transforming rectangular co-ordinates from one system of projection to another may arise from, various causes, One case, for example, with which the present writer is concerned involves the transformation, to the standard belt now in use, of the co-ordinates of some hundreds of points of a long existing triangulation projected a quarter of a, century ago on a, belt of Transverse Mercator projection, In this case conversion is complicated by the fact that the spheroid used in the original computation differs from that now adopted, and, also, the geodetic datums are not the same, The case in fact approaches the most general that can occur in practice, One step in one solution of this problem, however, is of perhaps wider Interest: that is, the transformation from one belt of Transverse Mercator projection to another when the spheroids and datums are identical. It is this special case which will be discussed here. 相似文献
15.
非规则采矿工作面积分区间确定方法 总被引：2，自引：0，他引：2
针对工作面形状多种多样的特点,本文采用二次曲线描述工作面水平投影边界,并且利用分段积分的方法处理更加复杂的工作面形状,合理地解决了非规则采矿工作面积分区间的划分问题;同时,给出了工作面形状系数的计算公式,整个计算过程利用计算机技术实现自动解算,避免了对任意曲边形工作面采用矩形分割的近似处理方法,提高了地面沉陷预计精度。最后,用实例说明了本文提供的对非规则采矿工作面的处理方法比现行处理方法具有更高的 相似文献
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《测量评论》2013,45(15):16-23
AbstractTHE formula for the projection is based upon the spherical assumption. To calculate it for the spheroid might be very complicated and would not be worth while. The projection is suitable for very large areas as a compromise between the Zenithal Equal-area projection on the one hand and the Zenithal Equidistant or Zenithal Orthomorphic on the other. Its application to an area as small as the British Isles would not serve any useful purpose. An analysis of its errors in the general case reveals some unexpected simplicities. This analysis is given below, followed by its application to the particular case of the British Isles on the ten-mile scale. This is done merely to find out what changes would have occurred if the supposed drawing of that map on Airy's projection had been real. 相似文献
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在GPS控制网数据处理中,对长度投影变形的处理至关重要。本文通过选取抵偿投影面很好的限制了矿区内的综合投影变形,为艾娜克铜矿工程测量控制网的建设提供了坚实的理论依据。同时,边长尺度强制约束法的运用进一步消弱了长度变形,使得新建控制网和原控制网能够很好的吻合,为利用前人的地质勘探及测量资料创造了条件。 相似文献
18.
跨带土地利用规划图的编制研究 总被引：1，自引：0，他引：1
在县级土地利用规划用图中,常涉及到跨投影带的地图拼接问题,一般使用邻带转换法实现跨带区域的地图显示,该方法在实际应用中存在面积和角度变形相对较大的不足.本文采用自定义中央经线的投影转带方法,经过高斯投影变换,较好地解决了县域范围的跨带拼接显示并有效控制了相关变形. 相似文献
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带锐度保持的斜投影B-样条图像缩放 总被引：11，自引：0，他引：11
基于B－样条的图像缩放相对于传统图像缩放方法（最近邻点、双线性、双三次等）的优势性在诸多文献和实验中得到了印证。但基于插值的B－样条的传统方法一样，没有考虑信息损失问题，是一种次优方法。为此Unser提出正交B－样条，并从理论上证明了其最优性。由于正交B－样条的采样池数在阶数大于3时难于获取，Lee发展易于计算且保持了相当精度的斜投影B－样条。B－样条良好的连续性使图像的边缘在缩放过程中被模糊了。为了克服这一问题，提出了带锐度保持的斜投影B－样条缩放，在缩放过程中利用B－样条的递推性质对存在一阶或二阶微分过零（即有小边缘）的采样区间缩小其积分范围至边缘附近，从而达到保持锐度的目的。实验结果表明该方法在保持缩放图像的连续性、清晰度方面都具有良好的效果。 相似文献
20.
《制图学和地理信息科学》2013,40(2):143-150
The choice of a projection for world distributions depends on a number of considerations. Primarily this involves the properties of equivalence and conformality. But there are instances where requirements regarding the use of these mutually exclusive properties would allow a compromise projection. This article presents the mathematical basis, a construction procedure, and an analysis of area and angular deformation of one such projection, a modified van der Grinten. Mathematical expressions are derived which are used to locate parallels and meridians. Parallels of the modified grid are straight lines located at an increasing distance from the equator. Meridians are arcs of circles intersecting the construction equator truly. Distribution of S and 2ω are shown. 相似文献