A RESECTION METHOD

Abstract

This is a variation of the well-known device of successive approximations. It was first used by the writer about 15 years ago on a Seismic (Geophysical) Survey when resections were continually employed to locate Shot Points and Geophonestations set on arcs of 10 to 15 miles radius. Speed was an important factor, and the normal text book methods of resection were very tedious. As far as is known the method is original. It is now used by many surveyors, and the writer trusts it will be of use to others. The method is easy to remember as it has no set formula and does not involve any elaborate geometrical construction.     

TWO PROBLEMS OF RESECTION: FURTHER NOTE

Abstract

An additional note on these problems, which were considered in No. 23, pp. 49-53, appears desirable. The “alternative form” on p. 51 was presented in a manner calculated to demand an explanation; since none has been forthcoming no apology is necessary for a further reference.     

A MACHINE METHOD OF RESECTION

Abstract

With the modern calculating machine in easy reach of every computer, the problem of determining the position of an occupied point from which direction observations have been made to three or more known points has become quite simple. The method outlined below is quite elegant in form and exceedingly simple on the machine. Let A, B, C be the three points whose co-ordinates (X₁Y₁), (X₂Y₂), (X₃Y₃) are known, and let (XY) be the co-ordinates of the point P which we wish to fix.     

NOTE ON LEVELLING UP THE PLATE

Abstract

1. The explanation of this fundamental operation in setting up surveying instruments, as well as of the theory of the level on which it is based, is, in my opinion, not sufficiently explained in text-books. I came across the problem while lecturing on the theory of surveying instruments. Below is an extract of the notes I made on the subject, which may have a didactical interest.     

NOTE ON THE PURPOSE OF THE PLATE BUBBLE

Abstract

It is hardly surprising that the more elementary aspects of a subject come to be so taken for granted that the learned authors of text-books fall into the error of oversimplifying them. As a result, the student is very often given a distorted idea of what is of fundamental importance.     

一种基于空间后方交会的三维坐标测量方法

提出了一种基于空间后方交会原理进行点的三维坐标测量的方法,实现了使用单张影像即可获取待测点的三维坐标,其原理简单,实用性强。     

NOTE ON THE REDUCTION OF CIRCUMMERIDIAN ALTITUDES TO THE MERIDIAN

Abstract

The method of reducing circummeridian altitudes or zenith distances to the meridian, using the factors m and n as tabulated by Chauvenet, is well known. The following method, which does not use these factars, has been faund both more convenient and more accurate in practice. The formula can be easily obtained by expanding m and n in powers of t, but far the sake af campleteness the derivatian is here given from the beginning.     

A NOTE ON THE CALCULATION OF POSITION LINES

Abstract

Since the computation of a set of star observations generally takes far longer than the actual observing, the method used in computing the results should be carefully chosen in those cases where a choice exists. The calculation of Position Lines is such a case.     

A NOTE ON THE TRIGONOMETRICAL SURVEY OF SOUTHERN RHODESIA

Abstract

After the completion of Simms's Geodetic Chain in 1901 and the publication of the results in 1905—Volume iii of the Geodetic Survey of South Africa—nothing further of a geodetic nature was done until 1928 when a short chain was run westwards from Simms's chain, at about latitude 17° 10′, to fix the Copper Queen mining area. The Eastern Circuit was commenced shortly after this; it runs from Salisbury eastwards to the Portuguese Boundary, southwards through Umtali to about latitude 20° and then westwards, joining Simms's chain again to the east of Bulawayo. Another chain running north from Simms's work has been commenced near Bulawayo. The several series are exhibited on the outline map attached.     

千年之交寄语

刚刚到来的 2 0 0 0年 ,已临近新世纪的开始 ,也即将迈向新的千年。在此我们向广大测绘科技工作者和本刊的广大读者致以最美好的祝福 !刚刚过去的 1 999年 ,是我国历史发展过程中具有特殊意义的一年 :我们隆重地庆祝了共和国的五十华诞 ,实现了澳门的顺利回归 ,我国首次可载人飞船试验成功 ,……。所有这些重大事件 ,进一步振奋了民族精神 ,激发了全国人民建设有中国特色社会主义的热情 ,对中华民族以崭新面貌进入新世纪、新千年产生了巨大推动力。即将开始的 2 1世纪 ,将是社会生产力发生革命性变革的知识经济时代 ,是知识不断创新、科技突…     

角度后方交会的最优构形

本文基于普通测量网优化设计理论，详细讨论了角度后方交会的最优定位问题，通过理论推证，解决了在给定三个已知点的前提下，如何选择最优待定点的问题，从而给出了后方交会的最优构形，本文所得结论不仅解决了测量理论上的一个基本问题，而且对实际工作应也有指导作用。     

A NOTE ON AZIMUTH DETERMINATION

Abstract

The purpose of this note is twofold; first, to criticize the “azimuth” section of the paper “Some Notes on Astronomy as Applied to Surveying”, by R. W. Pring (E.S.R., July 1952, xi, 85, 309–318),and secondly, out of these criticisms to develop an alternative method of making observations for azimuth. It will be apparent that this method owes much to the ideas put forward by Mr. Pring.     

A NOTE ON ISLAMIC ASTRONOMY

Abstract

The splendid vista of exploration of the dark chasms of space recently opened up by the coming into full use of the 200-inch Hale telescope at Palomar, California (the instrument is really a giant camera) and the new technique of radio astronomy which has revealed the presence of “radio stars” (at present so called for want of a better name)—dark bodies whose precise nature is not yet determined—might lead some people to think that the work of the ancient astronomers and their immediate successors counted now for little. But to do so would be grossly unjust not only to the achievements of ancient Greek astronomy but also to the valuable legacy left to the Middle Ages by Islamic astronomy.     

A NOTE ON CLARKE'S FORMULAE

Abstract

An elegant proof of Clarke's Formulae for lines of medium length has been given by G. T. McCaw. It is based on the properties of polar triangles in spherical trigonometry, and on the application of Legendre's Theorem.     

A NOTE ON HISPANO-MUSLIM ASTRONOMY

Abstract

A Previous articie dealt in brief outline with a few of the more prominent features of seven centuries (roughly) of Islamic astronomy from the 8th century (700) to the end of the 15th century (1400). First its rise under the early 'Abbâsid caliphs of Baghdad and, in about a century, its splendid flowering at the court of the Caliph AI-Mamun (813), whose capital city was renowned as the great seat of learning of the age. Next the middle period following on the Arab conquest of Spain, via Egypt and North Africa, which led to the founding of the Umayyad Amirate and Khalifate of Córdova (756). The immediately following period covered about four centuries of great and noteworthy astronomical activity by the so-called Moorish astronomers of Muslim Spain. Finally there was its resurgence in the further East in Samarqand, the capital city of the Timurid dynasty in Transoxiana, under the astronomer-prince Ulûgh Beg. After his “martyrdom” (assassination) in 1447 Muslim astronomy came to an end.     

TM图像的大地校正及其镶嵌方法研究

大地校正和数字图像镶嵌是应用遥感图像进行资源环境监测工作的基础,其精度的高低将对后续工作产生直接影响。基于经过系统校正的TM图像内部几何精度高的前提,本文提出一种快速实用的大地校正及图像镶嵌方法,该方法避免了传统方法在应用控制点建立拟合方程时耗时长的缺点,保证了TM镶嵌图像的几何精度.     

地图上多边形数据的快速数字化方法

本文针对传统数字化方法速度慢、劳动强度大等缺点,提出了一种利用扫描仪对地图进行扫描,再对扫描图像进行矢量化处理,从而完成多边形类地物的数字化的方法。而对每个多边形,只须在多边形中或附近任意采集一点,即可自动得到全部顶点的坐标。实验表明,该方法不仅可以数十倍地提高作业速度,而且还可较大幅度地提高数字化的精度,同时也大大减轻了作业员的劳动强度。