确定地理网络中心服务范围的一种算法

地理网络的中心服务范围在实际生活中应用广泛,传统方法一般用等时区或等距区表示。本文给出基于地理网络的中心服务范围的概念,并在邻接结点矩阵的基础上,应用广度优先搜索算法确定一个中心的服务范围。     

九寨沟自然保护区系列图研究

九寨沟是国家级自然保护区和重点风景名胜区。并载入联合国的《世界自然造产名录》．该沟生态环境十分脆弱，科学研究程度还相当低．两个国家自然科学基金课题对基生态环境进行了综台系统的研究，在此基础上编制而成的专题系列图填补了该区没有一套较完整图件的空白．文章介绍了系列图的编制背景、意义、选题、方法及特点等内容．     

A NEW METHOD FOR THE ADJUSTMENT OF A NETWORK OF TRIANGULATION

Abstract

A problem frequently encountered by surveyors in carrying out a system of triangulation, is the adjustment of a network of lower order triangulation to make it geometrically consistent with an existing triangulation of a higher order. For example, in Fig. 1 it will be assumed that the positions of the stations A, B, and C have already been determined and that it is now required to determine the positions of the stations a, b, c, d, e and f from the measured values of the internal angles of the network of triangulation shown. In practice, several different solutions have been suggested, ranging from rigorous least squares methods to semi-graphical solutions. The method described in this article is believed to be original and may prove of interest to surveyors.     

A CHANCE CORRECTION OF A TRAVERSE

Abstract

It sometimes happens that from a point on a line of theodolite traverse two fixed points are visible. In the absence of a visit to at least one of these points, B or C, or a precise knowledge of a bearing, it is not possible to fix absolutely the station, say A, of the traverse. Nevertheless, the fact remains that if the angle subtended by the fixed points is measured and found to be α, say, the station A must lie on an arc of a circle through BC “capable of” this angle α. Is there any assumption which is justifiable under these circumstances?     

THE CONFORMAL TRANSFORMATION OF A NETWORK OF TRIANGULATION

Abstract

In a recent issue of this Review, an example is given of the conformal transformation of a network of triangulation using Newton's interpolation formula with divided differences. While the application of the method appears to be new, attention should be drawn to the fact that Kruger employed Lagrange's interpolation formula in a discussion and extension of the Schols method in a paper which was published in the Zeitschrift für Vermessungswesen in 1896. A reference to this paper was given at the end of the paper, “Adjustment of the Secondary Triangulation of South Africa”, published in a previous issue of the E.S.R. (iv, 30, 480).     

A CURVE OF TRANSITION

Abstract

The original object of a transition curve was to ease the change from a straight line of communication to a circular line, or vice versa. It may even be laid out to connect one circular curve with another of different radius. In this manner the discomfort and even the danger to travellers in vehicles traversing such lines of way are obviated, abrupt variations of acceleration being overcome. The first curve to be used for this purpose was the elastica, introduced by Froude about 1842, and it is worthy of note that in their initial lengths all transition curves conform closely to this earliest form of easement. It is indeed obvious that, since the circle is a curve of the second order, an easing curve must be of a higher order ; the curve of the next higher order is of the third degree, and of all such curves the cubic parabola is the simplest, its equation being a²y ==x³.     

A CASE OF COUNTERSECTION

Abstract

Countersection is a jointure of intersection and resection. In addition to the elementary problem of a single triangle, whereof one angle is intersecting and one resecting—sometimes known as the problem of “lining in”—, there are many others of a nature somewhat more complex.     

A TEST OF AUTO-COLLIMATION

Abstract

In the July 1940 issue of the Empire Survey Review Mr A. V. Lawes contributes a valuable article, “The Application of the Gauss Method of Collimation to the Adjustment of Survey Instruments”. One section of the article describes four methods of adjusting collimators at solar focus, in other words of assuring that the emitted rays are parallel or that the target appears at an infinite distance. Mr Lawes rightly claims that auto-collimation is the most accurate of the four methods, and he warns readers that “the reflector used in this method must be as perfect optically as the objective”. However, he fails to give any method of testing the result obtained by following his directions, and experience suggests that auto-collimation may give a result considerably in error even though the reflector may with some justification be presumed to be good.     

SOLUTION OF PROBLEM IN THE SUBDIVISION OF A TRIANGLE

Abstract

The division of a triangle into three lots of equal area by lines, drawn from a point within it perpendicular to the sides, appears at first sight to be a very simple problem, in which an average surveyor would experience no difficulty in performing the necessary computations for the determination of the position of the required point where the division lines meet.     

A NOVEL METHOD OF MEASURING THE COEFFICIENT OF THERMAL EXPANSION OF INVAR

Abstract

In a letter published in a recent issue of Nature, Prof. L. F. Bates and Mr J. C. Wilson, of University College, Nottingham, have described a new and novel method of determining the coefficient of thermal expansion of invar. Although this method is hardly likely to be applied to the measurement of the coefficient of expansion of long invar tapes, such as are used by surveyors, yet it is so novel and ingenious in itself that a short reference to it may not be out of place in this Review. One extremely interesting thing about it is that no measurements of a length, or of changes of length, are involved.     

论三角测量单位权方差的先验估计与后验估计

三角洲量单位权方差的先验估值一般用经典菲列罗公式计算。实践中，经常出现三角测量单位权方差的先验估值不等于后验估值的情形．本文根据条件平差的原理，证明了单位权方基的先验估值是有偏估计，经典菲列罗公式是后验估计公式的特殊形式，并推导出了广义菲列罗公式。     

REMINISCENCES OF A ROVING PHOTOGRAMMETRIST

The author reminisces upon a career of almost 40 years as a practising surveyor photogrammetrist, both as a Royal Engineer officer and as a director of a commercial survey organisation. The reminiscences include service with the Survey of India, war time operations in the Middle East and South East Asia Command, and commercial surveys of all types in developing countries. Professional service with international surveying and photogrammetric organisations is also mentioned, with particular reference to the fraternal aspects of international photogrammetry.     

A METHOD OF OBTAINING PLATE CO-ORDINATES FROM THE MODEL CO-ORDINATES OF A PLOTTING INSTRUMENT

In analytical methods of photogrammetry, plate co-ordinates are obtained from stereocomparator and monocomparator observations. These specialist instruments are too costly an investment for small organisations. The paper describes a method of obtaining plate co-ordinates from model co-ordinates and gives the results of a test experiment.     

THE LEVELLING OF A THEODOLITE

Abstract

A Fully equipped theodolite is provided with plate levels, an alidade level, and a striding level. An instrument not so equipped has no title to be considered a “Universal Instrument”, that is to say, an instrument designed for every kind of both terrestrial and celestial measurement. Without a striding level, for example, nothing beyond relatively rough astronomical measures can be expected in general. Modern instruments, capable of giving considerable refinement in terrestrial measures, are frequently not furnished with a striding level; and it is sometimes assumed, with the tacit approval of the makers, that such instruments are equally capable of giving refined astronomical results. On the older type of instrument a striding level—rarely not supplied—could have been, and sometimes was, extemporized; it seems as if ignorance of astronomy of position has led, at least in part, to the construction of theodolites in such a manner as actually to render such extemporization difficult.     

BASIC TENETS OF A THEORY OF SCALING IN CARTOGRAPHY

The basic principles behind a theory of scaling in cartography are outlined and illustrated with a large number of examples. The following levels of scaling are used in the transformation of “(objective) empirical systems of relationships” to “abstract systems of relationships” for the purpose of their graphic representation: nominal, ordinal, interval, proportional or ratio, and absolute. While the first four levels (nominal, ordinal, interval, and ratio) are similar to those widely identified in the West, the absolute level represents what would be considered a special type of ratio scaling in Western practice. The paper includes criticism of certain graphic methods supposedly used by Western cartographers on maps employing the different levels of scaling (use of symbols differentiated by variations in internal structure, failure to correctly differentiate between interval, ratio, and absolute scaling, etc.). Measurement for mapping purposes should be based on careful analysis of the structure of relationships among the objects of mapping and on their preservation during numerical data transformations and graphic representation. Translated from: Vestnik Leningradskogo Universiteta, seriya geograficheskaya, geologicheskaya, 1986, No. 3, pp. 57-62.     

方差—协方差分量极大似然估计的通用公式

本文由概括平差函数模型出发，按极大似然做估计原则导出了适用于所有平差函数模型的方差分量估计的通用公式，由Ｋ．Ｋｕｂｉｋ和Ｃ．Ｒ．Ｋｏｃｈ所导出的两个公式都是它的特例。     

A MAP OF THE EMPIRE

Abstract

About sixteen years ago an apparent need of the time led the writer to consider the construction of a small-scale map of the British Empire. It was immediately obvious that such a sheet, prepared in a manner to reduce the errors of scale and bearing to figures approaching the minimum, would have to extend from the Yukon and across the Eastern Hemisphere to New Zealand_ Accordingly, it would involve an oblique projection, cutting the Equator at some angle to be investigated. Moreover, the depth of the map would necessarily be the least possible in order to conform with the desiderata above.     

一类隐蔽油气藏的TM图像解译模型

本文主要探讨了与压实褶皱有关的一类隐蔽油气藏的TM图像解译原理。根据压实褶皱的成因机制,对其盖层应力分布状况及其在后期构造运动中的受力变动情况进行了分析,提出与压实褶皱同时伴生的还有一系列特殊的裂隙型式,它们不仅为油气的储集提供了空间,而且在空间上还组成了特殊的组合型式(图像上呈现一定的图案),它们经过后期的风化剥蚀后可呈现出典型地貌特征。利用TM图像具有多波段、适中分辨率的优势可以在图像上对这些特殊的裂隙型式进行识别,从而可直接在图像上解译出埋丘、礁体、碎屑灰岩体、较纯的砂岩体、盐丘等形式的隐蔽油气构造。为进行油气勘探的靶区预测提供了一种更为迅速经济的手段。     

大区域数字图像的镶嵌设计与方法

本文详细论述了大区域遥感图像的数字镶嵌设计思想,提出了分区加大重叠的镶嵌方法,并 讨论了色调与反差匹配、几何配准和选择最佳匹配区域等问题。为了完善计算机图像镶嵌技术, 本文还提出了消除镶嵌接缝的加权平均调整灰度的方法。