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1.
《测量评论》2013,45(95):2-7
Abstract1. In the Sudan, as in Egypt, the greater part of the detailed survey control required for the cadastral mapping of the cultivated land beside the Nile has been in the form of traverse. This land is very flat and partly covered by crops at all times of the year, so that normal triangulation presents many difficulties, while there are many roads and canal banks which form natural routes for traverse. Nevertheless, the traversing is often slow because of the difficulty of carrying accurate measurements and lines of sight across ground made uneven by subsidiary irrigation canals, and in many cases encumbered by houses and date palms or other trees. Moreover a certain amount of triangulation is necessary to tie the surveys of the two banks together and to connect islands to the banks. 相似文献
2.
AbstractThis explains the formation of the Ordnance Survey of Northern Ireland as a separate institution in 1921, when it took over the map series which until that time had been part of the Ordnance Survey (U. K.) responsibility. As happened with many mapping organisations, replanning and reorganisation took place after 1945; this included a triangulation for Northern Ireland to provide a basis for a new Irt"sh Grid, and the introduction of the 1:1250 scale for major urban areas.The technical problems of reproduction and revision are then considered, and details given for each of the main series. 相似文献
3.
《测量评论》2013,45(44):322-324
AbstractIn the last three years about 250 miles of “precise” traverse have been surveyed in this country to provide control for detail surveys. A brief account of the results may be of general interest. The traverses are situated where trig. points are far apart, and the cost of subsidiary triangulation would have been excessive on account of the flat nature of the country. 相似文献
4.
none 《The Cartographic journal》2013,50(1):17-26
AbstractThe development of water transport, particularly of dock provision, was a potent influence on the nature and structure of some British towns. The impact of this development has been recorded in the detailed mapping of water transport specifically and in the mapping of towns generally. The nature and extent of this mapping is analysed in order to assess the degree to which early maps can be used as sources for the history of urban water transport and its impact on the townscape. 相似文献
5.
《测量评论》2013,45(79):2-16
AbstractTrimetrogon air surveys have been used extensively in the United States and Canada but seem to have had less favour on this side of the Atlantic in spite of the fact that large areas over here were photographed in this way during the last war. The Sudan is a very large country, but not a rich one; and up to the present it has not been able to undertake its own aerial photography. The gift of a very large number of American trimetrogon photographs covering half the country was therefore very welcome, and it seemed worth our while to see what could be done with them in spite of the known disadvantages of this type of photography for anything but small scale mapping. The methods of planimetric mapping from these photographs developed in the United States were expressly designed to be as simple as possible and to be capable of division into a number of easy tasks which could be performed by any educated person after a short course of training. Nevertheless we felt that they could be simplified a great deal more if the problem was approached from a different angle, particularly in view of the very high standard of flying which was apparent in the photographs covering the Sudan. 相似文献
6.
《测量评论》2013,45(1):12-15
AbstractDuring recent years a light apparatus has been made up in the Survey of India to provide a basis for minor triangulation. The idea originated with the writer when executing rough triangulation under war conditions, when the need was felt for checking work which had become liable to development of considerable error. The terrain was not such as to allow the measurement of an ordinary base of such a length as half a mile; nor were other facilities present. Accordingly a length of 200 feet was marked out, with the help of a 100-foot steel tape, on a fairly smooth site on rolling ground; and its subtended angle at a distance of about 1500 feet was measured carefully with numerous repetItIons. This 1500-foot length was in turn extended in a similar way to a 3-mile side of the triangulation. No great accuracy was looked for, but enough to rule out the possibility of gross mistake in the irregular triangulation. 相似文献
7.
《测量评论》2013,45(54):311-314
AbstractThere has always been a marked difference of opinion on the relative merits of the methods of bearings and of angles as applied to triangulation, though it is probable that the majority of writers prefer the method of bearings for first-order work. The subject was mentioned in a recent issue of this Review (vii, 47, 19). 相似文献
8.
《测量评论》2013,45(1):24-31
AbstractThe adjustment of a chain of triangulation for scale between measured bases is a comparatively simple matter. If it were possible to provide a similar method of adjustment for swing between measured azimuths and if the triangulation were based on a fixed datum, then there would be some hope of holding the chain fixed, without waiting until the completion of further chains rendered a net adjustment possible. This would be well worth doing. 相似文献
9.
《测量评论》2013,45(96):70-75
AbstractThe following paper describes some of the results obtained on it, tour of the Katsina and Kano Provinces of Northern Nigeria between November 1953 and February 1954. The purpose of the tour was to obtain latitudes and longitudes by astronomical observations for air photo mapping control in the northern parts of these provinces where triangulation is not available. The area is mostly flat and sandy. 相似文献
10.
《测量评论》2013,45(29):406-413
AbstractThis paper reviews and elaborates the application of the “Method of Systematic Relaxation of Constraints”, originally devised by R. V. Southwell for the calculation of the forces in frameworks, to the problem of the adjustment of survey networks to conform to the condition of least squares. The method is illustrated by the solution of a simple example of a triangulation network, and its application to larger surveys is discussed. 相似文献
11.
《测量评论》2013,45(21):386-395
AbstractAt the Conference of Empire Survey Officers held in London in 1931, an historical sketch was given of the progress of triangulation in Nigeria from its commencement to the end of the 1930 season, together with a brief summary of the proposed future programme. Since that date substantial progress has been made, and the recent completion of several important chains of triangulation and of the main precise traverse framework through the thickly forested regions of the Southern Provinces seems a convenient opportunity to place on record the present position. 相似文献
12.
《测量评论》2013,45(3):129-131
AbstractThe triangulation of Ceylon depends for its scale upon two bases, each about 5½ miles long, situated at Negombo on the West Coast (latitude 7° 10′) and at Batticaloa on the East Coast (latitude 7° 40′). Both bases are in low, flat country; brick towers up to 70 feet high had to be built over the terminals to enable observations to be taken to surrounding points. These lines have recently been re-measured. 相似文献
13.
《测量评论》2013,45(29):386-405
AbstractBeacon Lamps.—The design of electric directional projector used has been altered slightly as the triangulation has progressed, but for the sake of simplicity it is proposed to describe in detail only the final form, which is now a standard article manufactured by Messrs Cooke, Troughton, & Simms. 相似文献
14.
《测量评论》2013,45(92):276-277
AbstractIn survey work connected with Seismic (Geophysical) investigations, the nature of the operations is such that provisional points many miles apart have frequently to be located with a minimum of delay. When no map and no triangulation exists, the range finding method about to be described is very useful. The method can also be recomlnended for reconnaissance and exploration surveys. It was used by one of the R.A. Survey Regiments with success during the war. The essentials are a good theodolite and a steel tape. 相似文献
15.
《The Cartographic journal》2013,50(1):48-60
AbstractThe Lack hitherto of studies of cycle-touring mapping in Britain is noted, and some basic attributes of cycle touring, including speed, daily distance, gradients and wind, are described. Essential and desirable qualities for a cycle-touring map are enumerated, including the need to depict all rural routes available to cyclists; it is concluded that the optimum scale is in the range 1:100 000–1:126 720, and that relief should by contours at an interval not greater than 30 metres. National mapping in the optimum scale range which were published after 1945 are then reviewed, and reasons suggested as to why none has been kept in print. The mapping available for cycle touring in Britain in 2001 is Ordnance Survey (OS) 1:50 000 Landranger series contains all the necessary information, it is too bulky to be suitable; and that most of the other maps published in the optimum scale range have inadequate relief information and all offer very limited geographical cover. The potential competition for the OS 1:50 000 from a national map series in the optimum scale range is acknowledged, and an outline specification for a 1:125 000 series is described, which seeks to minimize that competiton whilst providing all the necessary information for cycle touring. 相似文献
16.
针对河道带状复杂地形布设控制点困难的问题及高精度的测量要求,本文探讨了一种结合PPK技术的无人机免像控河道测量方法。以DJI Phantom 4 RTK无人机为研究对象,分析了基于PPK的高精度POS辅助空三测量、相机镜头畸变纠正和航线设计等影响航测精度的关键技术,利用UAV-PPK软件对地面基站与无人机POS数据进行事后差分解算,获取高精度POS数据辅助空中三角测量。结合安徽省庄墓河河道治理工程进行试验,结果表明,基于PPK的免像控无人机航测获取了更高精度POS数据且成图精度满足河道1：500大比例尺测图要求。PPK辅助无人机航测提高了复杂地形测绘精度,为后续河道整治工作提供了更加精准的地形数据。 相似文献
17.
《测量评论》2013,45(92):242-254
AbstractThe application, in Oanada, of shoran electronic length measurement to surveying and mapping may be regarded as having been initiated in 1947, when experimental work by Federal Government bureaus was conducted in the vicinity of Ottawa over several long lines between stations of the first-order triangulation. During the succeeding two winters this work was continued, and the results indicated shoran as suitable for establishing position, in Canada's vast northland, quickly and with greater accuracy than by means of astronomic methods. It was realized that trilateration might fail in securing the necessary accuracy because of the many factors involved. Since no information was available, or even existed, from the experience of other survey organizations as to the error in position which might be generated in a comparatively long arc, the first work planned was for a 1100-mile axial-length arc between geodetic bases. This arc, situated in Manitoba and Saskatchewan, was measured in 1949 and 1950. The result indicated that shoran, with careful supervision of all details, could produce results of accuracy superior to astronomic positioning, which is the only reasonable and speedy alternative method of control for mapping at the present stage of development of the northern areas. 相似文献
18.
2000年,随着国家测绘局基础设施建设项目的完成并投入生产,标志着模拟测图时代的结束,测绘行业进入了数字化测绘的时代。从2000到2006年,测绘系统利用现代化的测图系统(主要包括影像扫描仪、PAT-B空中三角测量系统、磁盘阵列、服务器、网络系统、VirtuoZo与JX-4全数字摄影测量工作站等)陆续完成了包括大地水准面精化、全国骨干交通网数据采集、全国1:25万比例尺地形图数据库建设、1:5万比例尺地形图数据库建设等大型基础测绘建设项目,为国民经济建设与社会发展提供了有力的保障。社会的发展及民众的需求,向测绘行业提出了更高的要求,而技术的进步,则为解决这个问题提供了可能。 相似文献
19.
《测量评论》2013,45(69):318-322
AbstractThe Transverse Mercator Projection, now in use for the new O.S. triangulation and mapping of Great Britain, has been the subject of several recent articles in the “Empire Surpey Review. The formulae of the projection itself have been given by various writers, from Gauss, Schreiber and Jordan to Hristow, Tardi, Lee, Hotine and others—not, it is to be regretted, with complete agreement, in all cases. For the purpose for which these formulae have hitherto been employed, in zones of restricted width and in relatively low latitudes, the completeness with which they were given was adequate, and the omission of certain smaller terms, in the fourth and higher powers of the eccentricity, was of no practical importance. In the case of the British grid, however, we have to cover a zone which must be considered as having a total width of some ten to twelve degrees of longitude at least, and extending to latitude 61 °north. This means, firstly, that terms which have as their initial co-efficients the fourth and sixth powers of the longitude ω (or of y) will be of greater magnitude than usual, and secondly that tan2 ? and tan4 ? are likewise greatly increased. Lastly, an inspection of the formulae (as hitherto available) shows a definite tendency for the numerical co-efficients of terms to increase as the terms themselves decrease—e.g. terms in η4, η6, etc. 相似文献
20.
《测量评论》2013,45(22):460-469
AbstractSo much for the system. Now to describe the method of survey. Between 1902 and 1906 a chain of triangulation, extending from Zanzibar by way of the southern border of what is now Kenya Colony, and the northern and western shores of Lake Victoria to the Belgian Congo, had been surveyed by Anglo-German Boundary Commissions under G. E. Smith and Delmé Radcliffe as leaders. In 1902 a base line was measured near the middle of the Buganda Province by officers of the Uganda Survey Department. This was connected by triangulation to the Anglo-German chain, and several new chains were run across Buganda of an order of accuracy generally classified as that of tertiary triangulation. These chains are now known as the Uganda Main Triangulation, and form the backbone of the Buganda Cadastral Survey, popularly known as the “mailo” survey. 相似文献