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1.
《测量评论》2013,45(15)
AbstractWith regard to the cadastral maps of New Zealand it may be observed that the function of any particular class of map in this Dominion depends very much on whether it is a representation of the area, boundaries, and ownership of freehold lots, a subdivision of Native land, or one of the various leasehold tenures of Crown land. 相似文献
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AbstractFor the sake of the junior reader we may repeat an old and simple investigation. Let us suppose that the paper on which a map is printed undergoes a regular expansion p in one direction, say the X direction, and another regular expansion q in the Y direction, perpendicular to the former; it is required to know the effect of these expansions on the area of any parcel on the map. Note that, so far as the mathematics are affected, X and Y are not necessarily parallel to the margins of the sheet; we shall take them here as axes of any rectangular coordinate system. The symbols p and q are regarded as ratios, so that 100p and 100p represent the percentage expansions; if the paper contracts instead of expanding, no more is necessary than to change the sign. 相似文献
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《测量评论》2013,45(62):295-297
AbstractA Few notes will now be given on the subject of triangulation on which practically all the methods already outlined depend. If we have a triangulation ready for us on which to base our work, so much the better; but, if not, we must make every effort to carry one through either from our own measured base or from any existing points on the edge of our work. For reconnaissance survey, such a triangulation must be carried out with the greatest expedition; even if all refinements are sacrificed to speed, it is extraordinary how small the errors will be found to be when a more rigid triangulation is made. Any unorthodox method such as carrying through with a resected point or with an astronomical azimuth may be adopted. A bush will often make a good point to observe to, also piles of bushes with a flag on a reed or stick. 相似文献
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《测量评论》2013,45(96):87-92
AbstractVolumes of the earthwork involved along any proposed route maybe calculated from the taking of vertical cross-sections at regular intervals along the line—the spacing of the sections depending on the nature of the ground, the sections frequently being taken at points of whole through chainage and at points where cut gives way to bank and vice-versa. The process may be combined with that of slope-staking, in which case the areas may be calculated direct from the field notes, or alternatively the slope of the ground at each point considered may be shown on the drawing-board and the desired surface added, yielding in either case the cross-sectional area of cut or fill. 相似文献
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《测量评论》2013,45(74):162-174
AbstractThe comprehensive paper on the suspension of tapes by M. Hotine in the January, 1939, issue of the Empire Survey Review (v, 31, 2) did not contain any reference to this question, as was pointed out by A. J. Morley in a letter published on page 261 in the same volume (v, 34, 261). A brief analysis has been made by F. Yates of the theoretical effects of pulley eccentricity and misalignment (“Gold Coast Survey Department Records” VoL III, 1931, page 43) but I have not seen any further reference to the subject and have recently experienced the effects of such a defect in our own apparatus, so the followingnotes nlay be of interest. Before proceeding to details I will describe briefly those parts of the apparatus which are considered here and give a short summary of the whole paper. 相似文献
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《测量评论》2013,45(70):357-363
AbstractThere are no proper projections for use in geodetic work in a country which has great extensions both in latitude and longitude. For, if a single projection of any kind be applied in such a case, the linear and angular distortions would be so great at the boundary that it is very difficult or even impossible to apply the corrections to them. In order to render it possible for any projection to be applied, the area in question should be divided either into strips bounded by meridians or into zones bounded by parallels. In the former case the Transverse Mercator or Gauss’ projection may be used, while in the latter, the Lambert conformal projection is the most suitable. China is such a country as that mentioned above. It covers an area extending from 16°N. to 53°N. in latitude and of no less than sixty-five degrees in longitude. The problem of choosing a projection for geodetic work depends only on how the area is to be divided. It has been decided by the Central Land Survey of China to adopt the Lambert conformal projection as the basis for the co-ordinate system, and, in order to meet the requirements of geodetic work, the whole country is subdivided into eleven zones bounded by parallels including a spacing of 3½ degrees in latitude-difference. To each of these zones is applied a Lambert projection, properly chosen so as to fit it best. The two standard parallels of the projection are situated at one-seventh of the latitude-difference of the zone from the top and bottom. Thus, the spacing between the standard parallels is 2½ degrees. This gives a maximum value of the scale factor of less than one part in four thousand, thus reducing the distortions of any kind to a reasonable amount. The area between these parallels belongs to the zone proper, while those outside are the overlapping regions with the adjacent ones. All the zones can be extended indefinitely both eastwards and westwards to include the boundaries of the country. 相似文献
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《测量评论》2013,45(46):450-458
AbstractIf, one and all in our several ways, we are absorbed in helping to win the war, there are moments when it is possible to turn to our earlier loves, if but to relieve the strain. Not one of our hobbies, not a single insti tu tion that holds our affections and our memories, can emerge from this struggle just as it was. New thoughts and new methods are in the air, new service will be required, and, if principles remain largely unaltered, they, and the lessons we have learned, will be in peril, for continuity and knowledge have been rudely interrupted. It may do no harm to restate, however inadequately, some of those lessons—political, administrative and technical. 相似文献
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《测量评论》2013,45(79):16-18
AbstractPerhaps 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
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《测量评论》2013,45(8):93-101
AbstractThe commonly known methods for semigraphic fixation of trigonometrical stations depend on rectangular coordinates and bearings computed therefrom, but the extension of such methods to cases in which the distances are so great that second-order terms in coordinate differences become appreciable is never undertaken on account of the heavy computations involved. The following method, which is not found in the ordinary text-books, may be of interest to some surveyors not only because it can be applied to fixations using triangles of any size, but also because it can be employed to fix points in a triangulation that has been adjusted but not coordinated, since it is quite independent of coordinates and bearings. 相似文献
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AbstractAlthough the title of this paper may appear to some to refer to a rather humdrum subject which hardly deserves much serious thought or consideration, it is the writer's experience that the vital necessity for keeping clear records of survey work in a permanent form in which they can easily be referred to at any future time is not always sufficiently appreciated by those whose duties do not involve constant or frequent reference to the records of old work. Accordingly, the following notes and suggestions, which are based on practical experience, may be of service in drawing attention to a matter which is really of great practical importance. 相似文献
13.
《测量评论》2013,45(40):69-75
AbstractWhen a theodolite is used to measure an angle, the result will be subjected to certain instrumental and personal errors which affect the measurement. Such errors may be accidental or systematic. Those of the former type, which follow no law and which may with equal probability occur at any graduation, are more easily eliminated, since, if a very large number of readings is taken, it is probable that the errors will cancel out and that the mean will approximate very closely to the correct figure. Systematic errors are usually due to instrumental defects and rnay be expressed as a function of the reading itself; it is the object of the manufacturer to eliminate these as far as possible, since cancellation by reiteration or by repetition is not to be expected wholly. 相似文献
14.
In the field of biomass estimation, terrain radiometric calibration of airborne polarimetric SAR data for forested areas is an urgent problem. Illuminated area correction of σ -naught could not completely remove terrain features. Inspired by Small and Shimada, this paper tested gamma-naught on one mountainous forested area using airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar data and found it could remove most terrain features. However, a systematic increasing trend from far range to near range is found in airborne SAR cases. This paper made an attempt to use the relationship between distance to SAR sensor and γ-naught to calibrate γ -naught. Two quantitative evaluation methods are proposed. Experimental results demonstrate that variation of γ -naught can be constrained to a limited extent from near range to far range. Since this method is based on ground range images, it avoids complicated orthorectification. 相似文献
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《测量评论》2013,45(12):357-367
AbstractThe only essential difference between geodetic triangulation and any other of the fifteen “orders” of triangulation—which were once proposed, and happily rejected, at an International Conference—is that steps are taken to secure the high degree of accuracy necessary over the large areas to be covered. Some of the steps taken to secure increased accuracy may well be used to insure economy in secondary work, as for instance the use of fewer readings of a large instrument, or the use of luminous signals in conditions of poor visibility; while any surveyor may at any time have to connect his work to a geodetic triangulation, using much the same methods. 相似文献
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《测量评论》2013,45(23):44-48
AbstractIt sometimes happens that the limits or an area to be mapped by plane-table methods extend somewhat outside the scope of the previously observed triangulation. If the area outside the existing triangulation is not too great, it is often most convenient for the plane-tabler to extend the control himself as far as he requires it. 相似文献
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《测量评论》2013,45(62):300-311
AbstractChesterton did not, of course, intend this gibe to be taken literally. But the more we consider what he would doubtless have called the “Higher Geodetics”, the more we must conclude that there is some literal justification for it. Not only are straight lines straight. A sufficiently short part of a curved line may also be considered straight, provided that it is continuous (i.e. does not contain a sudden break or sharp corner), and provided we are not concerned with a measure of its curvature. Similarly a square mile or so on the curved surface of the conventionally spheroidal earth is to all intents and purposes flat. We shall achieve a considerable simplification, without any approximation, in the treatment of the present subject by getting back to these fundamental glimpses of the obvious, whether the formalists and conformalists accept them or not. 相似文献
20.
O. Remmer 《Journal of Geodesy》1969,43(2):99-122
A method for filtering of geodetic observationwhich leaves the final result normally distributed, is presented. Furthermore, it is shown that if you sacrifice100.a% of all the observations you may be (1−β).100% sure that a gross error of the size Δ is rejected.
Another and, may be intuitively, more appealing method is presented; the two methods are compared and it is shown why Method
1 should be preferred to Method 2 for geodetic purposes.
Finally the two methods are demonstrated in some numerical examples. 相似文献