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1.
《测量评论》2013,45(22):469-476
AbstractA Brief account of a survey, recently completed by me, of a block of land situated in Northern Rhodesia and some 3,000,000 acres in extent, may be of interest. The sketch-map opposite shows the geographical situation and.exterior boundaries of this block of land. It is seen that it stretches along the entire length of the Northern Rhodesia-Tanganyika Territory border, which is approximately 150 miles in length. 相似文献
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《测量评论》2013,45(98):164-177
AbstractIn the past there has been considerable discussion on the above subject in this Review. There is a bibliography at the end of this article in which the full titles of previous articles are given. For brevity, reference to them in the following text is made by number only. Recently, Gulatee summarized present knowledge and asked how other Survey Departments dealt with this matter. Consequently, it was considered that it would be helpful to set out in detail the procedure adopted by the Directorate of Colonial Surveys for obtaining trigonometric heights, with particular reference to primary and seoondary chains and nets. 相似文献
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ZHAN F. Benjamin 《地球空间信息科学学报》2011,14(1):1-9
Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 2002, and 2005 at stations of the Crustal Movement Observation Network of China (CMONOC) and examined gravity changes be-fore the occurrence of nine large (Ms≥6.8) earthquakes that ruptured within or near mainland China and Taiwan from November 2001 to August 2008. Results from this analysis show that significant gravity changes occurred across a large region before each of these nine large earthquakes, and these changes were detected by repeated ground gravity surveys through CMONOC. Although these gravity changes were significant, more research is needed to investigate whether these gravity changes could be viewed as precursors of large earthquakes. Limitations and uncertainties in the data include sparseness of the gravity monitoring network, long time intervals between consecutive gravity surveys, inevitable measurement errors, hydrological effects on gravity, and effects of vertical crustal movements on gravity. Based on these observations, we make several recommendations about possible future direc-tions in earthquake-related research using gravity monitoring data. 相似文献
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《测量评论》2013,45(32):67-85
Abstract Introduction.—Although much has been written on the various branches of surveying, few text-books do more than give the problem of Map Maintenance a passing mention. It is true that probably the major problem of the surveyor, when considering the world as a whole, is the urgent need of any sort of accurate map for most of its surface, yet at the same time quite considerable areas have already been surveyed, and the maintenance of these areas forms a very formidable problem in itself. Moreover, it is not generally realized that problems of maintenance necessitate a complete reorientation of technical outlook in comparison with questions of an initial survey. Clearly, when maps are being made in the first instance, the primary requirement is an adequate framework, whose main essentials are accuracy; rigidity and permanence. The filling in of the topographical detail and the final reproduction are matters of necessarily secondary importance. Furthermore, as the time required for the field work is large in comparison with the office stages, there is little actual or apparent gain in reducing the time taken on drawing and reproduction. In these circumstances the problem of an initial survey is essentially mathematical in its technique, little attention being required for the final stages of drawing and reproduction, which can be carried out, by craftsmen, at the unhurried pace which it has been their privilege to maintain in the past. 相似文献
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《测量评论》2013,45(25):136-140
AbstractIn a previous article on this subject (Empire Survey Review, January 1937) the writer sought to show that for trigonometrical observations of vertical angles made near noon in the Tropics the coefficient of refraction depends chiefly on height above ground level in the case of stations sited within a few hundred feet above the general level of the ground surface. Indeed, the computed values of the coefficient K show a definite and appreciable increase with “h”, the height of the observing station above ground level; it is usually assumed that K decreases with increase in height above the Mean-Sea-Level surface. From analysis of the results obtained by varying h but holding the heights above Mean Sea Level fixed the writer came to the conclusion that the variations in K could only be due to abnormal values of dt/dh and d2t/dh2, “t” denoting the air temperature. Now it is generally recognized by meteorologists that abnormal lapse-rates of temperature do frequently occur in the lower air layers in the Tropics; but up to the present time no temperature soundings in Nigeria are available. Recently, however, the writer came across the results of the aerological soundings made by an expedition in East Africa during the year 1908. The results of many of the soundings were of no use for the purpose of this paper; many of the observations were not taken at or near noon, and in others counterlapses of temperature in the lower layers indicated that conditions were not normal. A set of observations taken at Mombasa between 10 and 11 a.m. were eventually chosen as offering an example of what might reasonably occur in the lower layers of the atmosphere. 相似文献
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Russell D. Johnson 《国际地球制图》2013,28(1):41-45
Abstract Remote sensing is a powerful and accurate means of collecting data for wildlife management, particularly for large areas which are difficult of access and feature delicate ecosystems. Giant panda habitat in the People's Republic of China was evaluated by visual interpretation of multitemporal LANDSAT MSS images. The resulting map, combined with ground survey data, provides important information upon which management decisions can be planned. This case study illustrates that remote sensing techniques can make a significant contribution to the management programme for the conservation of a threatened animal species. 相似文献
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《测量评论》2013,45(78):338-348
AbstractRadar can be applied to surveying for precise measuren1ent of long lines, and as a navigational aid and position-fixing device for an aircraft performing a photographic survey. Trials of the radar method have recently been carried out in Australia using a modified “Shoran” equipment. The results of a large number of radar measurements of six distances, varying from 160 to 310 miles in length, indicate that an accuracy of 7 parts in 105 can be achieved. Equipment errors constitute the immediate limit to accuracy, but reasonable modifications would yield a figure of 2 parts in 105. Radar measurements can be completed in a fraction of the time required by normal ground survey methods, since a measurement of upwards of a hundred miles is made in a single step.As an aid to photographic surveying a straight-line track indicator actuated by data from the “Shoran” equipment has been designed and flight tested. Its performance enabled a pilot taking aerial photographs to keep the aircraft to within an average departure of less than 0.02 mile from any desired straight-line flight path. 相似文献
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《测量评论》2013,45(70):344-351
AbstractIn 1945 I was sent down to Yambio in the southern Sudan to carry out a detailed large scale survey of an area scheduled for the headquarters of an extensive development programme known as the Zande Scheme. The area is not far from the Nile-Congo watershed and the ground is very uneven, covered by ant-hills, and clothed in tall grass and thick bush which includes trees nearly a hundred feet high. Surveys of this kind had not been executed, in the southern Sudan previously except in towns. Nearly all the available experience of cadastral survey work in the Sudan,was therefore based on the very open and flat conditions of the north, where chaining along the ground is the natural and best way of measuring distances within the accuracy required. Except for the geodetic base measurement gear there was therefore nothing in the way of catenary apparatus available, though it was obvious that this would probably be the best equipment for the conditions to be expected in the south. However I had been engaged for most of my survey career up to this time on surveys of a more exploratory nature on much smaller scales such as 1/250,000, and I was unwilling to start experimenting until I had gained some experience in large scale work. 相似文献
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《测量评论》2013,45(8):105-108
AbstractAs air-photographs are being more and more used for survey purposes, Empire surveyors who have not yet made a thorough study of aerial survey may be interested in a little elementary photographic geometry and its application to map-making. A map may be described as an orthogonal proj ection of the ground upon a horizontal plane, reduced to some convenient scale, and a photograph as a conical projection of the ground upon the focal plane of the camera. If the focal plane is horizontal at the instant of exposure and the ground being photographed is perfectly level, the two projections are exactly similar and the photograph is indeed a map. Unfortunately these conditions which are illustrated in fig. 1 are extremely rarely encountered, and photographs usually need correcting for various distortions. 相似文献
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《测量评论》2013,45(9):171-177
AbstractThis is a résumé of the triangulation work completed within the Mandated Territory of Tanganyika, formerly German East Africa. The period covered includes the German Occupation down to 1915 and also the Colonial Office Administration from 1919 to the present day. 相似文献
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《测量评论》2013,45(58):122-133
Abstract Repercussions to Failure (1883–96).—So far we have only had occasion to consider the primary fiscal objective of the abandoned cadastral survey; but during the decade devoted to it (1879–88) other public activities had been developing which were no less dependent upon detailed maps for their effective and equitable operation. Pre-eminent among these was the irrigation service. During the previous part of the century various spasmodic efforts to construct general maps of the country had produced little more than a series of conventional diagrams, on scales of I : 100,000, or 200,000, depicting the approximate positions of the main waterways and villages throughout the Delta and Valley against a blank background. But it was upon knowledge of at least the broad pattern of cultivation, waste and marsh, of surface level and incline, throughout the countryside, that the satisfactory planning and operation of the interrelated system of supply and drainage channels depended; while the only regular means of accumulating this knowledge had been the abortive survey. For crude and unreliable as its work was and useless for its intended purpose, that survey had been providing for the first time village by village in important districts an interpretable picture of these broad effects. The Irrigation Service did its best to fill the gap by setting up a survey section to prepare a “hydrographic map” of Lower Egypt to meet its own requirements. The staff were mainly drawn from the disbanded cadastral survey and the methods used are reported to have been essentially the same; but the simpler character of the work evidently fostered certain changes. As the network of property boundaries was ignored the map scale was reduced of 1 : 10,000 and the plane table became the principal instrument of detail survey; and since villages were no longer working units continuous map sheet series were adopted for each province. This accentuated the need for a common basic framework; but the defects of such triangulation as existed appear, however, to have been accepted and extended, some of the more obvious gaps being patched with traverse. So the detail must have been subjected to a good deal of Procrustean treatment. Nevertheless, supplemented where necessary by lines of levelling, the work constituted an indispensable reconnaissance series for irrigation. 相似文献
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《测量评论》2013,45(14):496-498
AbstractIn the Empire Survey Review for April 1934 (No. 12, pp. 382–4), the Editor has raised the question of the function of the cadastral map. As he remarks, the question is not simple, but it is easier to say what the function of the map is than to decide of what the map should consist in order that it may fulfil its function. Broadly speaking we may state that the function of the map is to record the boundaries of landed property in such a manner as not only to afford a pictorial representation but also to supply data for the identification of these boundaries on the ground when occasion requires. Apart from this the map should show the areas of properties, as this information may be required for taxation purposes. 相似文献
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AbstractThe constant K in equation (12) represents distance expended through time lags in the instrument itself, and, although the value of K can be calculated from electrical data, this would not be very satisfactory and it would be better to determine it directly by means of observations over a line of known length. In addition, the point from which K would be reckoned is not a convenient one for actual field measurements. Instead of this, it is more convenient to choose an index mark on the instrument itself and referall measurements to this and thence to the mark over which the instrument is set up. 相似文献
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《测量评论》2013,45(7):24-28
AbstractMeasured deviations of the vertical have been used in support, or in destruction, of such pleasant little diversions as the theory of isostasy. They have also been used to adjust a triang~lation for swing, by methods which may fairly be criticized; but they have not, as far as I know, been used for reducing the horizontal measures of a triangulation to the standard conventional level of the spheroid of reference. In most cases such corrections would, of course, be too small to worry about, but it by no means follows that they are always small. In the case of a continental arc of meridian traversing a very disturbed mountainous region exhibiting certain constant tendencies, it should at least be demonstrated that they are small before the question can be considered finally settled. 相似文献
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Soetkin Vervust Manuel Claeys Boùùaert Bernard De Baets Nico Van de Weghe Philippe De Maeyer 《The Cartographic journal》2018,55(1):16-35
The eighteenth century Carte de cabinet of count de Ferraris is the first large-scale (1:11?520) topographic map of the entire Belgian territory, making it a valuable source of historical information. In the past, a number of studies have tried to assess the geometric accuracy of this map, but they all suffer from restricted technical capabilities for computing and visualizing the distortions, and most of them only focus on a limited number of the 275 map sheets. This paper therefore seeks to provide the first systematic and in-depth investigation of the map’s local geometric accuracy. Recently, two Belgian government agencies georeferenced the Flemish and Walloon part of the Carte de cabinet with a high level of detail, using some 30,000 ground control points to link the old map to the modern topographic map of Belgium. These data sets represent a new and unprecedented potential source of accuracy information. However, the high number of control points and our desire to compute distortions in an exact, local, quantitative and continuous way meant prominent techniques for studying the geometric accuracy of old maps, such as displacement vectors, distortion grids, triangular nets and the popular MapAnalyst software, were unsuited for this task. To meet all our requirements a new technique called Differential Distortion Analysis, which is influenced by the treatment of distortions in map projection theory, was used instead. Its advantages, structure and application to the Carte de cabinet are discussed in detail. The new technique allows calculating and displaying the map’s local angular and surface distortions with a very high spatial resolution. Consequently, it was possible to identify trends in the obtained levels of accuracy and to relate these to historical facts about the Carte de cabinet’s production process. This has resulted in important new insights into the map’s geometric accuracy. 相似文献
18.
《International Journal of Digital Earth》2013,6(2):221-239
Abstract An innovative and practical satellite image product is described that is ideal for applications in Northern Canada because of its wide area coverage and mapping-quality features. This product is generated from a new procedure developed at the Canada Centre for Remote Sensing (CCRS) for processing Landsat 7 imagery, and by extension, imagery from other Earth Observation satellites. By working with multiple satellite passes, each containing the equivalent of multiple scenes, the new procedure could dramatically reduce the turn-around time for generating georeferenced image products, and also increase their geometric and radiometric accuracy compared to those produced by the current methods. The objective of the process has been to generate satellite image mosaics covering large areas (e.g. >500 000 km2) with uniformly distributed errors at sub-pixel resolution. The paper discusses the theoretical basis of a photogrammetric adjustment for satellite imagery and the results obtained from several tests. The process is generic, involving a sensor model, a satellite orbit model and ground control information; thus it may be easily adapted to any satellite that allows for repeat coverage with overlapping paths. By performing an adjustment to correct the satellite position and attitude data prior to the production of orthoimage products, it is possible to create a mosaic with a single resampling process which minimises both the radiometric and geometric resampling artifacts. The results from three separate tests are presented, along with a discussion of the procedures that were followed in each case. All three tests have successfully demonstrated that sub-pixel sample size errors may be consistently obtained over large areas. A by-product process developed to support the measurement of ground control point coordinates for the satellite adjustment was the automatic matching of geographic features such as lakes and islands in vector data format. This has been a significant development in that it has eliminated manual intervention in the measurement of these features in the imagery, allowing the ground control for entire passes containing several scenes to be obtained in minutes instead of hours. 相似文献
19.
Abstract Introductory.—From time to time the question of the relation between the metre and the foot is raised, most frequently perhaps from Africa. Had there been no more than a single metre to consider the question would no doubt arise but seldom: the most recent authoritative comparsion would be generally accepted. But actually it is the existence of two metres—the “ legal” and the “international”—which complicates the question, so much indeed that there is no metrological factor which has influenced survey, British and foreign, more than the relation between these two metres. The question was discussed in this Review (I, 6, 277, 1932), but memories grow shorter, attention is more diffused, and besides there is required a more explicit statement of the situation as it affects British surveyors, especially in Africa, whence the question has been raised anew. To illuminate it, unfortunately the need recurs to repeat some well-known facts. 相似文献
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《测量评论》2013,45(56):42-52
AbstractOn the occasion of the Empire Survey Conference in 1931 we had the privilege of arranging at the Science Museum an Exhibition of Cadastral Maps and Land Records which had been somewhat hurriedly collected from the United Kingdom, the Dominions, India, eleven Colonies and Protectorates, three Mandated Territories and six foreign countries. As there is some vagueness in the application in English of the French word cadastre, it may be advisable before proceeding to say that while in Europe this word, with its German and Italian equivalents, originally applied to a record of landed property (biens fonds) compiled for fiscal purposes and is commonly still so defined in standard dictionaries, we have throughout used it in the wider sense it has gradually been assuming generally of any analogous record concerned with subdivisions of land occasioned by human use, whether the purpose to be primarily served is fiscal, juridical, economic or otherwise. Cadastral survey is the process by which the parcels of land dealt with are defined, and can be located again at need. The noun, which is rarely mentioned in English, was from the earliest days applied to the whole conspectus of the record: registers, maps, supporting documents, etc. We use the term land record loosely, and somewhat unsatisfactorily, in this comprehensive sense because the more convenient and exact one-cadastral record-has not so far found a place in British practice with its associates: cadastral maps and cadastral survey. 相似文献