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1.
《测量评论》2013,45(9):167-168
AbstractIn the reduction of geodetic triangulation the computation of the spherical excess of each triangle is of great importance; for unless the amount of spherical excess is known, the accuracy with which the angles have been observed cannot be assessed, nor can the triangle itself be computed by the simple formulae applicable to plane triangles. 相似文献
2.
《测量评论》2013,45(54):314-327
AbstractConsidering first of all the general case of a triangle ABC with base AB and apex angle C, the assumption is made that at A and at B only one orienting ray has been observed at each point besides the forward rays to C and that at Conly B and A have been observed. In other words, the three angles of the triangle have been observed. The adoption of General Schreiber's rule with regard to the weights of forward and back directions is valid here, since it may easily be shown that, when the weight of a forward ray is one-half of the weight of a back ray, the adjusted angles of a triangle conform to the condition of least squares. 相似文献
3.
《测量评论》2013,45(18):218-225
AbstractI. Although surveying is generally conducted on the principle that there should be more observations than are mathematically necessary for the calculation of the required results, the determination of the position of a point by resection from three fixed points is an exception to the principle. In observing a round of angles at a point, one of them can be inferred, but it is always observed in order to obtain a check by closing the round; a point fixed by intersections is generally observed from four or five surrounding points, although only two shots are strictly necessary. But the problem of resection from three points is a “minimum-of-data” problem, that is, the observations are only just sufficient to fix the point, and there is nothing extra to give a check on the result. 相似文献
4.
三角网至规则格网的生成在地形内插和遥感影像配准中小面元微分纠正等方面都具有重要应用。其关键在于快速准确地搜索每个格网点所在的三角形,然后根据三角网顶点信息内插每个格网点的信息。针对格网点在三角网中的定位和内插计算量大的问题,本文提出了一种自适应扫描线填充算法以快速准确地搜索定位出每个格网点所在的三角形;针对地形内插或者小面元微分纠正中每个三角形具有相同运算的特点,采用GPU技术实现了TIN格网内插以及小面元微分纠正并行加速。分别采用大范围自动空三获取的三维点进行地形内插以及大尺寸遥感影像进行微分纠正实验,结果表明本文方法可以有效提高效率。 相似文献
5.
《测量评论》2013,45(20)
AbstractThe usual method employed is to plot or to compute the traverse from each end; the poin t having the same coordinates in each route is the station where the gross angular error occurred. There is, however, a method of finding the error by plotting the traverse one way only. Let us consider the traverse having the known terminals A B (see Fig.). Suppose that the error occurred at the point P and that the final point obtained (plotting the traverse from A) was B′ in place of the correct point B. We can easily see that the triangle PBB′is isosceles, and that therefore a straight line bisecting BB′at right angles will meet the traverse in the required point P. 相似文献
6.
Y. Bock R. I. Abbot C. C. Counselman S. A. Gourevitch R. W. King A. R. Paradis 《Journal of Geodesy》1984,58(2):211-221
The Macrometer Model V-1000 is a geodetic positioning instrument that uses the radio signals broadcast by the GPS satellites.
The Macrometer is the only GPS user equipment commercially available that does not require any of the GPS codes. The Model
V-1000 receives only the 19-cm wavelength signals from GPS although similar instruments, built for the U.S. Air Force Geophysics
Laboratory, receive both the 19-and the 24-cm wavelengths. In this paper we summarize the results of two years of field testing
of the V-1000. This instrument, observing four or five satellites fof a few hours, yields a point position accurate within
several meters in each coordinate: latitude, longitude and ellipsoidal height. All three components of the relative position
vector between a pair of points can be determined within 2 parts per million of the distance, given a similar schedule of
observations. This accuracy has been obtained for intersite distances from one kilometer to several thousand kilometers.
Macrometer is a trademark of Aero Service Division, Western Geophysical Company of American, 8100 Westpark Drive, Houston,
Texas, 77063, U.S.A. 相似文献
7.
《测量评论》2013,45(26):194-206
Abstract Reconnaissance.—It has been possible to draw up a “paper scheme” for most of the primary triangulation by examination of large-scale topographic maps for possible obstructions to the proposed rays (after due allowance for curvature and refraction along the ray); the fact that certain of the proposed lines had been definitely observed in the existing primary or secondary triangulation was of course of material assistance. Since, however, all observations were to be to luminous beacons, requiring a close organization, it would have been unsound to draw up an observing programme on the strength of this paper scheme alone. The omission of a few key rays, subsequently found to be obstructed by timber, whose height cannot be appreciated from maps, or by local features which had grown up since the last triangulation, would have entailed some confusion in the observing programme, the establishment of additional stations for occupation during a later season, and the reoccupation of stations surrounding such additional points; in short, the probability of a year's delay in obtaining sufficient material for adjustment, and a considerable loss of economy. Arrangements were accordingly made for the paper scheme of the English main chain to be verified and amended on the ground by special reconnaissance parties in 1935, when in fact no instruments or beacons were available to commence observing in any case. In the same way, field reconnaissance of the Scottish main chain and of the Western figure (Wales and the S.W. peninsula) was completed in 1936 and a start made on the Eastern figure (East Anglia and S.E. England), so as to get the reconnaissance and station preparation well ahead of observing. Experimental reconnnaissance of a few secondary blocks—for which, as also for the primary reconnaissance of the flat enclosed East Anglian country, paper schemes are practically useless—was also commenced in 1936 and is being pushed ahead rapidly in 1937. 相似文献
8.
9.
The temporal change of the rotation vector of a rotating body is, in the first order, identical in a space-fixed system and
in a body-fixed system. Therefore, if the motion of the rotation axis of the earth relative to a space-fixed system is given
as a function of time, it should be possible to compute its motion relative to an earth-fixed system, and vice versa. This
paper presents such a transformation. Two models of motion of the rotation axis in the space-fixed system are considered:
one consisting only of a regular (i.e., strictly conical) precession and one extended by circular nutation components, which
are superimposed upon the regular precession. The Euler angles describing the orientation of the earth-fixed system with respect
to the space-fixed system are derived by an analytical solution of the kinematical Eulerian differential equations. In the
first case (precession only), this is directly possible, and in the second case (precession and nutation), a solution is achieved
by a perturbation approach, where the result of the first case serves as an approximation and nutation is regarded as a small
perturbation, which is treated in a linearized form. The transformation by means of these Euler angles shows that the rotation
axis performs in the earth-fixed system retrograde conical revolutions with small amplitudes, namely one revolution with a
period of one sidereal day corresponding to precession and one revolution with a period which is slightly smaller or larger
than one sidereal day corresponding to each (prograde or retrograde) circular nutation component. The peculiar feature of
the derivation presented here is the analytical solution of the Eulerian differential equations. 相似文献
10.
《测量评论》2013,45(12):368-370
AbstractThe first part of the season (November–January) being spent on urgent reconnaissance of both the primary chain and secondary series in the Samarahan, Sadong, and Simanggang Districts, it was not until loth February that observing was begun. The programme called for two observers, one occupying primary stations and one occupying the secondary points, the secondary rays from primary stations being observed at one occupation of the point. 相似文献
11.
在建筑工程施工中,经常遇到建筑物轴线控制桩破坏殆尽的情况,在此情况下,如果初次设点时,在轴线两端的建筑物上弹有墨线,那么根据墨线,在跨轴线两侧任意设置两点,观测四个角度值和两侧两点间距,经解算三角形,即可很快求得,任意设置点至轴线上某点的距离,就能很快将轴线恢复.本文介绍了用Java语言编写在手机上运行的java解算程... 相似文献
12.
I. J. Dowman 《The Photogrammetric Record》1971,7(38):232-236
The paper describes how a computer can be programmed to form triangles from points, having x, y and z co-ordinates and selected in an arbitrary manner, to calculate the area of each triangle and to determine the volume of the prism above or below the triangle. The sum of these volumes gives the total volume of a body. 相似文献
13.
一种新的球面三角投影:等角比投影(EARP) 总被引：5，自引：0，他引：5
设计一种面向球面三角形的新的投影--等角比投影(Equal Angle Ratio Projection,EARP),该投影包括平行以及同轴两种模式,支持正六面体、正八面体、正二十面体等柏拉图立体(Plato Polvhedron)[1～3]以及任意Voronoi球面三角剖分.可以选择任意形状的投影平面三角,投影坐标由球面弧角度与特征球面弧角度之比决定,弧线族上的均分点与2维投影面上均匀分布的三角网格顶点相对应.本文给出了该模型正八面体以及正二十面体(EARPIH)的具体方程式的求解,证明了基于QTM的GoodChild[4]和Otoo[5 ]的离散投影方程是该投影的两种特例,并探讨了面积比性质,发现EARPIH投影的面积比变动范围相对狭小.支持该投影的球面剖分模型的地理坐标与球面三角格网之间的坐标转换可转换为均分三角网格的计算问题. 相似文献
14.
《测量评论》2013,45(66):166-174
AbstractThe computation of geographical coordinates in a geodetic triangulation is usually carried out using Puissant's method, in which the assumption is made the sphere radius ν (the radius of curvature of the spheroid perpendicular to the meridian) not only touches the spheroid along the whole small circle of latitude ?,but also, since ρ (the radius of curvature in meridian) is very nearly equal to ν it makes such close contact with the spheroid that the lengths of sides and angles of a geodetic triangle may be considered identical on both sphere and spheroid. 相似文献
15.
《测量评论》2013,45(72):90-92
AbstractWhen developing the argument leading to the stereographic solution of the spherical triangle and its application to field astronomy (Empire Survey Review, Vol. 2, No. 10, October, 1933, p. 226) A. J. Potter rendered a very useful service in demonstrating how proofs of the two practically useful properties of the stereographic projection can be provided along lines that demand no more than simple geometry in their development. The proof advanced for the unique property that any circle on the. sphere remains a circle in projection is at once simple and complete; but in the attempt to prove that the projection is orthomorphic in the sense that angles everywhere remain true there is the difficulty that the argument was developed for what must be regarded as a special case in that the point was located on the great circle through the origin of the projection normal to the plane of the projection. Treatment of the problem along similar lines for other points away from the central meridian does not seem to admit of such ready solution and the alternative approach suggested here, while still not demanding. anything beyond simple geometry for its understanding, affords a proof for a general case. 相似文献
16.
剥蚀法计算GPS观测网独立环闭合差 总被引：1，自引：0，他引：1
在GPS测量中，往往需要计算三角形、多边形闭合差，以便及时发现观测粗差、衡量GPS观测精度。本文提出了剥蚀法计算GPS观测网独立环闭合差，这种方法利用计算机自动确定观测网中的独立环个数，并计算所有独立环闭合差。它适合各种复杂的观测图形，所计算的独立环个数是唯一的，独立环为观测网中的最小闭合单元，并且环与环之间不出现包含和重复。 相似文献
17.
R. Reudink R. Klees O. Francis J. Kusche R. Schlesinger A. Shabanloui N. Sneeuw L. Timmen 《Journal of Geodesy》2014,88(6):617-622
We report on the susceptibility of the Scintrex CG-5 relative gravimeters to tilting, that is the tendency of the instrument of providing incorrect readings after being tilted (even by small angles) for a moderate period of time. Tilting of the instrument can occur when in transit between sites usually on the backseat of a car even using the specially designed transport case. Based on a series of experiments with different instruments, we demonstrate that the readings may be offset by tens of $\upmu $ Gal. In addition, it may take hours before the first reliable readings can be taken, with the actual time depending on how long the instrument had been tilted. This sensitivity to tilt in combination with the long time required for the instrument to provide reliable readings has not yet been reported in the literature and is not addressed adequately in the Scintrex CG-5 user manual. In particular, the inadequate instrument state cannot easily be detected by checking the readings during the observation or by reviewing the final data before leaving a site, precautions suggested by Scintrex Ltd. In regional surveys with car transportation over periods of tens of minutes to hours, the gravity measurements can be degraded by some 10 $\upmu $ Gal. To obtain high-quality results in line with the CG-5 specifications, the gravimeters must remain in upright position to within a few degrees during transits. This requirement may often be unrealistic during field observations, particularly when observing in hilly terrain or when walking with the instrument in a backpack. 相似文献
18.
Cartosat–1 is the first Indian Remote Sensing Satellite capable of providing along-track stereo images. Cartosat–1 provides forward stereo images with look angles +26° and −5° with respect to nadir for generating Digital Elevation Models (DEMs), Orthoimages and value added products for various applications. A pitch bias of −21° to the satellite resulted in giving reverse tilt mode stereo pair with look angles of +5° and −26° with respect to nadir. This paper compares DEMs generated using forward, reverse and other possible synthetic stereo pairs for two different types of topographies. Stereo triplet was used to generate DEM for Himalayan mountain topography to overcome the problem of occlusions.For flat to undulating topography it was shown that using Cartosat-1 synthetic stereo pair with look angles of −26° and +26° will produce improved version of DEM. Planimetric and height accuracy (Root Mean Square Error (RMSE)) of less than 2.5 m and 2.95 m respectively were obtained and qualitative analysis shows finer details in comparison with other DEMs. For rugged terrain and steep slopes of Himalayan mountain topography simple stereo pairs may not provide reliable accuracies in DEMs due to occlusions and shadows. Stereo triplet from Cartosat-1 was used to generate DEM for mountainous topography. This DEM shows better reconstruction of elevation model even at occluded region when compared with simple stereo pair based DEM. Planimetric and height accuracy (RMSE) of nearly 3 m were obtained and qualitative analysis shows reduction of outliers at occluded region. 相似文献
19.
推导出方向后交点住精度的显函数公式;用解析法导出对称交会时最佳交会角和最佳点精度;用无约束最优化共轭梯度法,求出一般情况下方向后交最佳交会角和点位精度;求出同一三角形三个内角分别作顶角进行后交定位的最佳点位,得出三角形内只有一个最佳点位的结论,给出一种选择近似最佳点位的方法. 相似文献
20.
《测量评论》2013,45(16):72-80
AbstractIt was suggested some time ago in the Review (E.S.R., vol. ii, no. 9, p. 182) that observing procedure in a ruling triangulation should be made the subject of a discussion at the forthcoming Empire Survey Conference. I hope it will be. We shall perhaps learn why India finds thirty measures necessary, as no doubt they are necessary in India, whereas South Africa and Southern Rhodesia are able to secure much the same degree of accuracy from the same instrument with only eight; why Canada, again with the same instrument, prefers the golden mean of sixteen; why some of us still prefer the measurement of angles to directions vvhile others would insist entirely on the measurement of directions from a “close” R.O. It is only by pooling the experiences gained in diverse circumstances that we can avoid being overborne by our own successes or failures, encountered possibly in very exceptional circumstances which may not recur. 相似文献