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《测量评论》2013,45(18):236-241
AbstractI. Introduction.-For some little time the Ordnance Survey was engaged upon the problem of transforming the rectangular coordinates of trigonometrical stations from the Cassini projection to the Gauss Conformal projection. The problem was complicated by the fact that the Cassini projection, as is well known, was applied to a number of meridians of origin, a different meridian being used for a county or a group of counties. It was proposed, however, to have only one meridian for the Gauss projection and to drop the county meridians completely. In both projections the northings were measured from the same parallel. 相似文献
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《测量评论》2013,45(72):90-92
AbstractWhen developing the argument leading to the stereographic solution of the spherical triangle and its application to field astronomy (Empire Survey Review, Vol. 2, No. 10, October, 1933, p. 226) A. J. Potter rendered a very useful service in demonstrating how proofs of the two practically useful properties of the stereographic projection can be provided along lines that demand no more than simple geometry in their development. The proof advanced for the unique property that any circle on the. sphere remains a circle in projection is at once simple and complete; but in the attempt to prove that the projection is orthomorphic in the sense that angles everywhere remain true there is the difficulty that the argument was developed for what must be regarded as a special case in that the point was located on the great circle through the origin of the projection normal to the plane of the projection. Treatment of the problem along similar lines for other points away from the central meridian does not seem to admit of such ready solution and the alternative approach suggested here, while still not demanding. anything beyond simple geometry for its understanding, affords a proof for a general case. 相似文献
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《测量评论》2013,45(32):85-89
AbstractThe necessity of transforming rectangular co-ordinates from one system of projection to another may arise from, various causes, One case, for example, with which the present writer is concerned involves the transformation, to the standard belt now in use, of the co-ordinates of some hundreds of points of a long existing triangulation projected a quarter of a, century ago on a, belt of Transverse Mercator projection, In this case conversion is complicated by the fact that the spheroid used in the original computation differs from that now adopted, and, also, the geodetic datums are not the same, The case in fact approaches the most general that can occur in practice, One step in one solution of this problem, however, is of perhaps wider Interest: that is, the transformation from one belt of Transverse Mercator projection to another when the spheroids and datums are identical. It is this special case which will be discussed here. 相似文献
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《测量评论》2013,45(60):217-219
AbstractMap Projections.—A matter that should have been mentioned in the original article under this title (E.S.R., vii, 51, 190) is the definition of a map projection. In the list of carefully worded “Definitions of Terms used in Surveying and Mapping” prepared by the American Society of Photogrammetry (Photogrammetrie Engineering, vol. 8,1942, pp. 247–283), a map projection is defined as “a systematic drawing of lines on a plane surface to represent the parallels of latitude and the meridians of longitude of the earth or a section of the earth”, and most other published works in which a definition appears employ a somewhat similar wording. This, however, is an unnecessary limitation of the term. Many projections are (and all projections can be) plotted from rectangular grid co-ordinates, and meridians and parallels need not be drawn at all; but a map is still on a projection even when a graticule is not shown. Objection could be raised also to the limitation to “plane surface”, since we may speak of the projection of the spheroid upon a sphere, or of the sphere upon a hemisphere. Hence, it is suggested that “any systematic method of representing the whole or a part of the curved surface of the Earth upon another (usually plane) surface” is an adequate definition of a map projection. 相似文献
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AbstractAbout sixteen years ago an apparent need of the time led the writer to consider the construction of a small-scale map of the British Empire. It was immediately obvious that such a sheet, prepared in a manner to reduce the errors of scale and bearing to figures approaching the minimum, would have to extend from the Yukon and across the Eastern Hemisphere to New Zealand_ Accordingly, it would involve an oblique projection, cutting the Equator at some angle to be investigated. Moreover, the depth of the map would necessarily be the least possible in order to conform with the desiderata above. 相似文献
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Steven E. Greco 《地球空间信息科学学报》2013,16(4):288-293
ABSTRACTConceptually, the theory and implementation of “map projection” in geographic information system (GIS) technology is difficult to comprehend for most introductory students and novice users. Compounding this difficulty is the concept of a “map projection file” that defines map projection parameters of geo-spatial data. The problem of the “missing projection file” appears ubiquitous for all users, especially in practice where data is widely shared. Another common problem is inadvertent misapplication of the “Define Projection” tool that can result in a GIS dataset with an incorrectly defined map projection file. GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors. A novel pedagogical device is introduced in this paper: the seven possible states of GIS data with respect to map projection and definition. The seven possible states are: (1) a projected coordinate system (PCS) that is correctly defined, (2) a PCS that is incorrectly defined, (3) a PCS that is undefined, (4) a geographic coordinate system (GCS) that is correctly defined, (5) a GCS that is incorrectly defined, (6) a GCS that is undefined, and (7) a non-GCS. Recently created automated troubleshooting tools to determine a missing map projection file are discussed. 相似文献
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《测量评论》2013,45(71):16-19
AbstractField work for the 1/1,250 scale re-survey of Great Britain was fully described in an article by Brigadier R. P.Wheeler in the April, 1948, issue of this Review (ix, 68, 234–247). The object of this article is to outline the method’ of reproduction of these plans and of the resultant 1/2,500 scale plans of urban areas. The 1/2,500 series covering rural areas is a separate problem, one of revision rather than re-survey. Experiments are in hand now to find out the best ways to provide field material and produce the final plans on National Grid sheet lines. The 1/1,250 scale series will contain about forty thousand plans and the 1/2,500 series of the same areas about nine thousand. It is therefore important that production methods should be straightforward and maintain an economical balance between the use of men and machines. 相似文献
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《测量评论》2013,45(15):16-23
AbstractTHE formula for the projection is based upon the spherical assumption. To calculate it for the spheroid might be very complicated and would not be worth while. The projection is suitable for very large areas as a compromise between the Zenithal Equal-area projection on the one hand and the Zenithal Equidistant or Zenithal Orthomorphic on the other. Its application to an area as small as the British Isles would not serve any useful purpose. An analysis of its errors in the general case reveals some unexpected simplicities. This analysis is given below, followed by its application to the particular case of the British Isles on the ten-mile scale. This is done merely to find out what changes would have occurred if the supposed drawing of that map on Airy's projection had been real. 相似文献
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Abstract Introductory Remarks.—A line of constant bearing was known as a Rhumb line. Later Snel invented the name Loxodrome for the same line. The drawing of this line on a curvilinear graticule was naturally difficult and attempts at graphical working in the chart-house were not very successfuL Consequently, according to Germain, in 1318 Petrus Vesconte de Janua devised the Plate Carree projection (“Plane” Chart). This had a rectilinear graticule and parallel meridians, and distances on the meridians were made true. The projection gave a rectilinear rhumb line; but the bearing of this rhumb line was in general far from true and the representation of the earth's surface was greatly distorted in high latitudes. For the former reason it offered no real solution of the problem of the navigator, who required a chart on which any straight line would be a line not alone of constant bearing but also of true bearing; the first condition necessarily postulated a chart with rectilinear meridians, since a meridian is itself a rhumb line, and for the same reason it postulated rectilinear parallels. It follows, therefore, that the meridians also must be parallel inter se, like the parallels of latitude. The remaining desideratum—that for a true bearing—was attained in I569 by Gerhard Kramer, usually known by his Latin name of Mercator, in early life a pupil of Gemma Frisius of Louvain, who was the first to teach triangulation as a means for surveying a country. Let us consider, then, that a chart is required to show a straight line as a rhumb line of true bearing and let us consider the Mercator projection from this point of view. 相似文献
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《The Cartographic journal》2013,50(2):94-97
AbstractThis projection is critically examined and the claim that it has the property of equivalence is refuted. The basis of a modified cylindrical equal-area projection is rigorously defined, and the inaccuracy of the Trystan Edwards projection demonstrated. 相似文献
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ABSTRACT A geometric algorithm for Tilted-Camera Perspective (TCP) projection is proposed in this paper based on the principle of perspective projection. According to that, the difference between TCP projection and External Perspective (EXP) projecton is analyzed. It is put forward prerequisites making these two projections were compatible, and some examples are given. 相似文献
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《测量评论》2013,45(48):59-68
Abstract“RECTIFICATION” is the term used to describe the production from a tilted air photograph of a print or image from which the effects of tilt have been eliminated. It consists, essentially, in the projection of the original photograph on to another selected planenormally, but not necessarily, representing the horizontal. 相似文献
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《The Cartographic journal》2013,50(2):106-108
AbstractIn 1967 Dr Arno Peters made his first public claim to have designed a world map superior to Mercator and all others. Although professional cartographers have pointed out that the projection is not original or unique, the map has gained a not inconsiderable measure of political acceptance. 相似文献
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《测量评论》2013,45(32):66-67
AbstractThe projection in question is a mean between Mercator's and the Equal-Area Cylindrical Projection which is formed by orthographic projection from the sphere upon the circumscribing cylinder. Both projections are computed on the spherical assumption. Mercator's Projection is, of course, the best known of the orthomorphic group; the Equal-Area Cylindrical Projection is the simplest of the equal-area group. Each projection may be said to represent an extreme case; and the mean between them may perhaps, for some purposes, be a useful compromise. 相似文献
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Richard Barnes 《International Journal of Digital Earth》2020,13(7):803-816
ABSTRACT Spatial analyses involving binning often require that every bin have the same area, but this is impossible using a rectangular grid laid over the Earth or over any projection of the Earth. Discrete global grids use hexagons, triangles, and diamonds to overcome this issue, overlaying the Earth with equally-sized bins. Such discrete global grids are formed by tiling the faces of a polyhedron. Previously, the orientations of these polyhedra have been chosen to satisfy only simple criteria such as equatorial symmetry or minimizing the number of vertices intersecting landmasses. However, projection distortion and singularities in discrete global grids mean that such simple orientations may not be sufficient for all use cases. Here, I present an algorithm for finding suitable orientations; this involves solving a nonconvex optimization problem. As a side-effect of this study I show that Fuller's Dymaxion map corresponds closely to one of the optimal orientations I find. I also give new high-accuracy calculations of the Poles of Inaccessibility, which show that Point Nemo, the Oceanic Pole of Inaccessibility, is 15?km farther from land than previously recognized. 相似文献
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AbstractWhen computing and adjusting traverses or secondary and tertiary triangulation in countries to which the Transverse Mercator projection has been applied, it is often more convenient to work directly in terms of rectangular co-ordinates on the projection system than it is to work in terms of geographical coordinates and then convert these later on into rectangulars. The Transverse Mercator projection is designed in the first place to cover a country whose principal extent is in latitude and hence work on it is generally confined to a belt, or helts, in which the extent of longitude on either side of the central meridian is so limited as seldom to exceed a width of much more than about 200 miles. 相似文献
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《测量评论》2013,45(31):2-36
AbstractThe method of accurate linear measurement by means of suspended Invar steel tapes or wires has, since its introduction by Jäderin about the beginning of this century, entirely replaced the older methods of base measurement by bars or rods. It is not surprising, therefore, that the theoretical basis of the method—including a determination of the form of the curved tape and of its horizontal projection—should have received close attention. The most valuable recent contributions to the subject, since Benoit and Guillaume's classic work La Mesure Rapide des Bases Geodesiques, are by Professor and Major Henrici and by the late Mr A. E. Young. 相似文献