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1.
The accuracy of heighting from Large Format Camera (LFC) stereo-photographs of the New England area was evaluated using a conventional mirror stereoscope equipped with × 6 binocular eyepieces and a precision parallax bar. It was discovered that a large differential ω had to be removed before acceptable height results could be obtained. Enlarged portions of the LFC photographs covering city areas of Boston, Massachusetts and Providence, Rhode Island could be used to produce accurate height results. It was concluded that analogue mapping from LFC photography using simple instruments could be economically carried out at a scale of 1:100000 or smaller, with a contour interval of 100 m to 120 m.  相似文献   

2.
《测量评论》2013,45(79):16-18
Abstract

Perhaps the most important requirement in any air survey is that the ground surveyed points used as a basis for controlling the photography should be correctly identified on the photographs. In the writer's experience more difficulties and delays have been caused by misidentifications of these points in the field than perhaps from any other cause, and yet very little has been written on this important subject, and there are no generally recognised methods of point identification. In this article a system of point identification is described which the writer has used with success in certain types of country, and it is hoped that the article may lead to more contributions on the subject.  相似文献   

3.
《测量评论》2013,45(72):67-74
Abstract

Since 1899 cadastral mapping in the Sudan has been concentrated along the banks of the Nile from the Egyptian frontier to latitude 13°N., in the towns, and in the area of the Gezira, south of Khartoum, where cotton has been developed. These surveys were controlled by theodolite and steel tape either in the form of traverses or rectangulation. The early triangulation was used mainly to control topographical surveys, for it was essential to cover the whole country as rapidly as possible with a series of maps on scale 1: 250,000. As a consequence much of this early triangulation is of a relatively low order of accuracy, indifferently marked on the ground, and unfit for inclusion in a framework for medium and large scale mapping.  相似文献   

4.
《测量评论》2013,45(10):221-225
Abstract

The graphical methods developed at the War Officeof mapping from strips of vertical photographs are generally widely known. It may be fairly said that they frequently present a reasonably economical method of mapping the planimetry of a country on medium topographical scales when there is a normal third-ordertrigonometrical control, but that so far it has not been possible to provide economically for the accurate depiction of the ground relief. The reason, for this failure is due to the fact that the control required fot contouring is about one fixed height per square inch of map, and the cost of providing this control will normally be of the same order as the cost of mapping by ground methods.  相似文献   

5.
《测量评论》2013,45(84):278-279
Abstract

Many methods of mapping from air photographs “without control” have been proposed from time to time. Usually this means having no control, or very little, on the ground. The following paper describes some experiences of mapping without controlling the photographs inter se, a suggestion which must rank as improper with a Photogrammetrist.  相似文献   

6.
《The Cartographic journal》2013,50(3):237-248
Abstract

Since 1906, South Africa boasted an excellent geodetic framework, and in 1920 an official Trigonometrical Survey Office (TSO) was established. In spite of these achievements, the country, by the 1930s, still lacked reliable topographical maps. One reason for this was that the secondary and tertiary triangulations of the country were still incomplete; another was that the decision-making process as regards surveys and mapping rested with a variety of statutory bodies instead of just one. In 1934, A. D. Lewis, Director of the Department of Irrigation, committed his department to execute a general topographical survey of the country and produce a topographical map on a scale of 1∶500?000. Lewis’ decision met with much resistance from within the country and abroad, but the project was completed in a record period of 4 years. Published just before the Second World War, the map was of inestimable value to the South African Defense Force. It not only became the standard topographical map of large parts of South Africa for many years, but its contents also figured in the first map series of the TSO.  相似文献   

7.
In attempting to assess the possibilities of mapping from earth satellites, various factors which do not occur with aerial photography must be considered. The orbital characteristics of satellites are discussed from the point of view of their effects on photographic scale and coverage and the problems of taking and retrieving photography from satellites are outlined. An evaluation of the possibilities and limitations of mapping from both single and stereoscopic television pictures and normal frame photography is made and the tentative conclusion reached that topographic mapping from earth satellite photography may only be considered seriously for the scales 1 : 250 000 to 1 : 1 000 000 and for a minimum contour interval of 100 m. The economy of this very small-scale mapping is at present very doubtful in view of the current costs of building and launching a suitable satellite. Any extensive programme of satellite photography for mapping purposes could pose some difficult legal and political problems if the photography was made freely available.  相似文献   

8.
《测量评论》2013,45(73):119-130
Abstract

1. This new method of adjusting air photographs numerically to a uniform scale on a final map grid has already been described by the writert, where it concerns a large block-adjustment. The method to be described in this paper is the application of the same principle to the adjustment of photographic strips, covering narrow land areas and coastlines.  相似文献   

9.
《测量评论》2013,45(6):249-253
Abstract

The International Boundary Commission is a body which has been created by treaty between Canada and the United States for the purpose of surveying, mapping, and marking the international boundary between the two countries and for subsequently maintaining that boundary in a state of effective demarcation. The Commission consists of two Commissioners and their staffs. One Commissioner is appointed by His Britannic Majesty upon the recommendation of the government of Canada, the other is appointed by the President of the United States. Each government pays the salaries of its own officers, but the other expenses are borne equally by the two governments. It should be noted that the International Boundary Commission is a body quite distinct and separate from the International Joint Commission, with which it is sometimes confused. The functions of these two Commissions do not overlap or duplicate each other in any way. The International Joint Commission has jurisdiction over all cases involving the use, obstruction, or diversion of boundary waters, and, in addition, when requested by the government of either Canada or of the United States, examines and reports upon such other questions of difference as may arise in the vicinity of the boundary, involving the rights, obligations, or interests of either country in relation to the other or to its inhabitants. The consideration of such questions does not come within the purview of the International Boundary Commission. On the other hand, to the latter body pertains exclusively the work of surveying, mapping, and marking the boundary, and the location of any point on the boundary in connection with any question that may arise between the two governments.  相似文献   

10.
以无人机航摄技术在大比例尺(1∶1 000、1∶500)地形图测绘中的应用为研究目的,采用固定翼无人机平台,搭载非量测型数码相机,于河北某矿区进行航摄大比例尺地形图制作实验,通过外业实测点位数据对测图高程及平面精度进行评估。实验结果表明:通过严控误差影响因素无人机航摄技术可以满足1∶1 000比例尺测图精度要求,1∶500比例尺测图精度无法满足。最后,基于精度评定数据对误差产生的原因进行了深入分析与探讨,为无人机航摄技术测绘大比例尺地形图应用的可行性及可靠性提供了经验。  相似文献   

11.
《测量评论》2013,45(70):344-351
Abstract

In 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   

12.
The paper entitled The Photogrammetric Society Analogue Instrument Project was published in The Photogrammetric Record 14(82): 565-582 (October 1993). Extracts have appeared in each subsequent issue such that all the standard types of analogue instruments mentioned in the catalogue have now been included, some 28 instruments in all. In this final extract, the three remaining instruments listed in the catalogue are dealt with. All are of a type usually known as approximate solution instruments because they did not attempt any form of accurate space intersection but relied on applying a number of corrections to a model formed on the assumption that the photographs being used were true verticals taken at the same altitude. The accuracies achieved by such instruments depended both on how close the photography being used was to this ideal situation and on the degree of sophistication in the design of the analogue correctors incorporated in any particular instrument. The raison d'être for such a genre of instrument was essentially one of cost. Any organization faced with the requirement to produce small scale topographic mapping of an extensive region within a reasonable period of time might consider spending its available funds on a larger number of cheaper approximate solution instruments, always provided that an acceptable degree of accuracy could be maintained. Fortunately for such projects the specification would normally be for mapping of a graphical order of accuracy produced from high altitude photography. At such altitudes, stable flying conditions and small camera tilts of the order of 3° to 4° could realistically be expected. However, to obtain the best possible results from such photography, the best images possible should be provided for the operator, a factor sometimes overlooked by some manufacturers in their attempts to produce cheaper instruments. In view of the background to the development of British photogrammetry mentioned in previous extracts, it is perhaps surprising that a successful instrument of this type was not produced in the UK at a much earlier point in the era of analogue photogrammetry. Approximate methods were certainly favoured and promoted but only as far as planimetric maps were concerned. For these, form lines rather than contours were drawn when height information was considered necessary. However, when it was finally produced, the Thompson CP1 (manufactured by Cartographic Engineering Ltd.) proved to be an excellent instrument of its type and less approximate in its solution than most of its competitors. The other two instruments described in this extract are the Zeiss Stereotope and the Galileo-Santoni Stereomicrometer. The instruments are introduced in the order of their appearance on the market, which is also the order of the degree of sophistication found in the analogue computers they employed to reduce the errors introduced by any camera and airbase tilt present in the photography.  相似文献   

13.
Abstract

When Lord Kitchener ordered Sir Ian Hamilton in 1915 to command land operations on Gallipoli he gave him a solitary old One Inch map and denied him any air forces. When Winston Churchill had earlier sent the Royal Navy to break through to the Black Sea, he had ensured that the Royal Naval Division withdrawn from fighting on the Western Front was accompanied by a Naval Air Squadron as its forward reconnaissance element. Ernest Dowson, the Surveyor General of Egypt, appointed to provide local mapping support, soon convinced the Naval pilots of the value of air photography taken systematically to meet his map-making requirements. In September 1915 Dowson wrote a Secret technical report demonstrating for the first time to British Commanders the practicality of mapping from specified aeroplane photographs of the operational area.  相似文献   

14.
Dimension estimation of landslides is a major challenge while preparing the landslide inventory map, for which very high-resolution satellite data/aerial photography is required, which is very expensive. An alternative is the application of drones for such mapping. This study presents the utility of drone/unmanned aerial vehicle (UAV) for mapping and 3D reconstruction of two landslides near IIT Mandi, Himachal Pradesh. In this study, we used DJI Phantom 3 Advanced drone to collect high-resolution images of landslides. Features in the images were automatically detected, described, and matched among photographs using scale invariant feature transform (SIFT) technique. The 3D position and orientation of the cameras and the XYZ location of each feature in the photographs was estimated using bundle block adjustment. This resulted in sparse 3D point cloud, which was densified using Clustering View for Multi-View Stereo (CMVS) algorithm. Finally, surface reconstruction was done using Poisson Surface Reconstruction method, which was visualised in open source software CloudCompare. The 3D model, generated from drone images, was validated using field measurements of some objects, and 3D surface created from total station. Various quantities i.e. width (length), height and perimeter were measured in the 3D drone model and verified with total station data. The differences among all the measured quantities for both the landslides are less than 5% keeping the measurements of total station as reference. The 3D reconstructed from the sets of photographs is very accurate giving the measurements up to cm level and even small objects could be easily identified. In addition, digital elevation model (DEM) of sub meter resolution could be easily generated and used for various applications. Hence drone-based imagery in combination with 3D scene reconstruction algorithms provide flexible and effective tools to map and monitor landslide apart from accurately assessing the dimensions of the landslides.  相似文献   

15.
基础航空摄影产品是服务于社会各行各业的重要基础测绘成果,但多数市、县级基础测绘规划任务中缺少对基础航空摄影的规划。本文以测绘行业的相关法律法规为基础,探索了在市、县级基础测绘规划实施过程中,基础航空摄影的规划方案和基于基础航空摄影测量的数据采集方法,从而提高了基础测绘产品服务经济社会发展的水平和效率。  相似文献   

16.
分析了数字摄影测量相机(DMC)在航空摄影测量及大比例尺数字化成图中遇到的问题,如摄影比例尺的选择;数字解析空中三角测量野外像控点间航向基线数、旁向航线数、区域网总航线数的确定;摄影测量平台软件的选择;对计算机硬件的要求;摄影精度、加密精度、成图精度等.  相似文献   

17.
本文利用ADS40相机进行航空摄影,对海岛(礁)区域1∶2000比例尺成图精度进行了分析,比较了差分GPS与精密单点定位技术应用于ADS40航摄的精度。试验结果表明,ADS40相机可满足海岛(礁)大比例尺成图航摄的精度要求,缩短成图周期,精密单点定位技术的平面精度与差分GPS方法相当,高程精度较差,从工程角度考虑,海岛(礁)大比例尺成图时架设地面GPS基站比较稳妥。  相似文献   

18.
Abstract

Most projects which involve planning of rural areas and towns in developing countries require maps, but many of these countries do not have sufficient large-scale mapping suitable for this purpose, or maps which are up-to-date. With environmental-friendly projects becoming highly desirable, up-to-date and accurate maps are vital. As most large scale mapping projects require technical assistance, this paper discusses aid agreements with donor countries. These opportunities could be of benefit to private entrepreneurs. This paper also examines the project management approach for introducing mapping projects to developing countries. It makes special reference to a large mapping project in Zimbabwe in which the author was personally involved.  相似文献   

19.
Abstract

A frequent requirement in post‐construction management of a land pipeline route is to detect revegetation status on a time-sequential basis (usually 5‐10 years). The principal advantage of video is the capacity to provide, in a cost‐effective manner, information required for such a very narrow and long strip target utilising the narrow view angle and dynamic stereo coverage. This paper reports that a video strip monitoring technique requiring solely end lap has been specifically developed with focus on such a narrow and long strip target (e.g. 20‐30m wide and several hundred km long). Such large‐scale video systems are often discussed as being inadequate for a change‐detection application due to geometric and radiometric calibration problems. In spite of such limitations, changes of major thematic land cover classes, particularly for the rapidly recovered target of a pipeline corridor, could be detected successfully by visual or quantitative methods and through further ‘patch dynamics’ analysis in a GIS environment. The results of this study indicate that such calibration problems are generally not a major drawback in acquiring change‐detection information in a practical operational application which requires mostly generalized thematic mapping of relatively simple classes. The results also indicate that Video Strip Mapping (VSM) could be extensively used for other examples of linear thematic mapping.  相似文献   

20.
Aerial photography for archaeology has been developing its approaches and techniques over the past 100 years so that it now integrates the results of reconnaissance with extensive interpretative and analytical surveys. This paper introduces the philosophy and approach of the English Heritage (EH) Aerial Survey team, covering aerial reconnaissance and the National Mapping Programme (NMP), as well as the potential developments and opportunities in Europe. In the 1980s there was a debate over the nature of the evidence derived from aerial photographs, especially how to describe archaeological features. As part of NMP a classification and recording system has been devised which meets most of the users' needs, be they national organisations, county archaeologists, commercial contractors or university-based researchers. The maps and records produced by NMP are used to further our understanding of the past human settlement in England, not only at the individual site level, but also in regional or landscape contexts. This paper provides an overview of the current progress of NMP and acts as an entrée for explaining the current research and recording of archaeological landscapes throughout Europe. Recent developments in Britain and Europe have provided the opportunity for a greater priority to be given to aerial survey and accelerating programmes of mapping. In Europe the ending of the cold war has allowed greater access to aerial photographs and the possibility of beginning new reconnaissance, as well as introducing new forms of remote sensing. All these developments have led to a transformation of our understanding of prehistoric, Roman and medieval archaeology.  相似文献   

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