A FIFTY-YEARS RETROSPECT

Abstract

The International Map of the World.—Officially known as the Carte du Monde au Millionième, this undertaking has the following history. At the International Geographical Congress which was held at Bern in 1891, Professor Dr. Albrecht Penck proposed the construction, by all the nations of the world, of an International Map on the scale of 1 to 1 million. This idea was unanimously approved, and a very sketchy outline was roughed out for its prosecution. Of this outline the chief item that has survived is the size of the sheets, which were to be six degrees in longitude by four in latitude. Well, time passed and nothing much happened. Year after year there were a few murmurs at congresses about the map, and a few, a very few, sheets were printed, some by Section “F” of the British War Office. There was no general organization to look after the prosecution of the map, and there were no adequate regulations for its construction. Generally speaking, the official map-making institutions were out of touch with the scheme, and geographical societies and congresses had no money and no power to carry it out.     

A FIFTY-YEARS RETROSPECT

Abstract

The Ordnance Survey after the War.—I might class the four years after the War, during which I remained at the head of the Ordnance Survey, as interesting but troublesome. As is well known, an entirely unreasonable impression was spread about that, now that the War was over, there would be a period of great prosperity, and that we should all live like fighting cocks. Well, things did not work out like that. There was a Select Committee on National Expenditure (1918), and this Committee recommended a lengthening of the period of revision of the large-scale maps of the United Kingdom and a consequent, ultimate, reduction of establishment by 500 men. The Treasury later on insisted on a reduction by 600, including Ireland.     

A FIFTY-YEARS RETROSPECT

Abstract

On returning from India I was posted to the command of a depot company at Chatham, a kind of employment which has the advantage of giving one who has been serving in the East a complete change of ideas. The life was pleasant enough, though the duties were mainly of a routine nature. I was not sorry after a year of this agreeable enough life to be given a further change in the shape of special employment on the West Coast of Africa.     

A FIFTY-YEARS RETROSPECT

Abstract

Early in 1902 I accepted with some misgivings the post of Instructor in Surveying at the School of Military Engineering, Chatham, in succession to Major A. C. MacDonnell. I had hardly joined at Chatham when Sir Thomas Holdich offered me the post of second in command of the Chile-Argentina Boundary Commission. However, my new chief, the Commandant, would not let me go, so I settled down to a few years of very pleasant work at Chatham. The first thing to do was to introduce a correct method of computing the geographical coordinates of the trigonometrical stations of a topographical survey, a matter over which my predecessor had suffered a rebuff. Now, however, the War Office personnel had changed; no opposition arose, and the thing was done.     

A FIFTY-YEARS RETROSPECT

Abstract

The Ordnance Survey and the War.—I shall not inflict upon the readers of this Review any very long account of the work of the Ordnance Survey during the Great War. At that time the work of the Survey suffered from one necessary disadvantage: all the young men on its establishment, whether in the R.E. Companies or on the Civil Staff, left for active service. As a slight compensation for this inevitable dislocation all money difficulties in the preparation of maps for war disappeared.     

A FIFTY-YEARS RETROSPECT

Abstract

About this time an excellent Instructor in Surveying was appointed to the School of Military Engineering in the person of Major A. C. MacDonnell. He had served in India,—though not on the Survey of India,—and, being well acquainted with the excellent Indian frontier survey methods, resolved to introduce them into the course at Chatham. So he started using the system of computing latitudes and longitudes from trigonometrical data by Puissant's formulæ, in the form used by the Survey of India. But he had reckoned without his host, the higher authorities. His dreadful deed became known, and the matter was referred to three eminent officers for their opinion. The three officers were Sir Charles Wilson, Director of Military Education, Sir John Ardagh, Director of Military Intelligence, and Sir John Farquharson, Director-General of the Ordnance Survey; none of the three had had any personal acquaintance with the method in question, although two of them had directed the Ordnance Survey, and Sir Charles Wilson in the sixties had carried out some very interesting surveys in Palestine and Sinai. Well, these three distinguished officers solemnly condemned the Indian method as being unsuitable for use at Chatham, and MacDonnell had to revert to more primitive ways, which later on would have made impossible the conduct of a properly managed boundary commission or such surveys as that of the Orange Free State, Uganda, or Northern Sinai, or much of the technical work on the Western Front during the War. And that was that.     

A FIFTY-YEARS RETROSPECT

Abstract

In 1911 Lord Carrington, then President of the Board of Agriculture and Fisheries, offered me the appointment of Director-General of the Ordnance Survey of the (then) United Kingdom, and I need not say that I accepted the appointment. I took over from my predecessor, Colonel S. C. N. Grant, on the 22nd August. The Ordnance Survey was a single department charged with the mapping, on a great variety of scales, of England and Wales, Scotland, and Ireland. Officers and men were freely interchangeable between the different countries.     

A FIFTY-YEARS RETROSPECT

Abstract

On returning from Central Africa I was posted, for ordinary duty, to Edinburgh, and after a short time I found myself again on the Ordnance Survey. Late in 1899 the South African War broke out, and early in 1900 I was sent out to South Africa in command of a very small Field Survey Section. But before describing the limited activities of this Section it may be as well to give some idea of the attitude of the higher civil and financial authorities towards the proposition that it is desirable to be prepared with maps of possible theatres of war.     

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?     

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。     

A VIDEO TRACKING SYSTEM FOR A LIGHT AIRCRAFT

Due to the inherent poor downward visibility of typical light faced wing aircraft the tracking of parallel flight lines is a problem. Various solutions have been examined and details of a remotely controlled colour video system are given.     

利用DEM的“环形”洪水淹没算法研究

以数字高程模型(DEM)为基础,结合水流扩散的基本原理,设计出一种新的“环形”淹没算法。本算法充分利用栅格DEM数据的特点和GIS的优势,将二维分析技术和三维演示平台进行结合,针对小区域范围的洪水演进过程,更精细地模拟出洪水淹没的过程,为科学地确定洪水淹没范围和水深分布、洪水风险图制作、防洪指挥调度和洪涝灾害的损失评估提供准确的评判依据。     

基于微机的数字修测系统

本文介绍了一种基于微机的数字修测系统。利用现势性较好的像片和已有的地图，通过扫描仪扫描后，借助计算机实现矢量、栅格数据的叠置，进行地图的修测或地图数据库的更新。     

环境星CCD数据大气校正研究

利用6S模型和同步气象资料,对国产环境与灾害监测预报小卫星HJ-1 A的CCD1传感器数据进行了大气校正和反射率反演。同时对CCD1传感器1～4波段大气校正前后的反射率变化进行了对比研究,发现大气校正后的1～3波段的地面反射率明显降低,4波段的地面反射率升高;利用同步野外实测地面数据对大气校正后的反射率数据进行了检验,两者结果基本一致;此外,还进行了定量化误差分析,以同步野外实测地面数据作为标准,将大气校正后的反射率数据与之对比,分析了可能带来误差的原因。结果表明,利用6S大气校正方法能够有效去除HJ-1 A星CCD图像的大气影响,获取地物绝对反射率。     

A new multi-C/A code acquisition method for GPS

An acquisition method is proposed which saves processing time and rapidly finds the Global Positioning System (GPS) satellite with high receiving power. The idea is to combine two or more Coarse/Acquisition (C/A) codes to process acquisition, thus called “multi-C/A code acquisition method.” The proposed method will change the procedure of conventional Fast Fourier Transform acquisition slightly, and it has the capabilities to combine with other acquisition methods to perform signal acquisition simultaneously. In order to show how this multi-C/A code acquisition method may improve the Time To First Fix at the cold start, the real raw Intermediate Frequency data from a GPS software receiver are used to validate this multi-C/A code acquisition method. The results show that this method can save at least 23% processing time and it is able to detect the satellite more rapidly.     

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.     

A RELATIVE ORIENTATION

The author draws attention to the basic function of the stereoplotting instrument and its operator within the overall concept of productive aerial surveying and goes on to describe in some detail the circumstances of the arrival and use of the first stereo-autographs to be installed in the United Kingdom. Wartime conditions resulted in these instruments playing an unusual but effective role in data acquisition for intelligence purposes. Their performance at that time clearly demonstrated their suitability for the large scale surveys that were soon to be in such demand.