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1.
《测量评论》2013,45(12):368-370
AbstractThe first part of the season (November–January) being spent on urgent reconnaissance of both the primary chain and secondary series in the Samarahan, Sadong, and Simanggang Districts, it was not until loth February that observing was begun. The programme called for two observers, one occupying primary stations and one occupying the secondary points, the secondary rays from primary stations being observed at one occupation of the point. 相似文献
2.
《测量评论》2013,45(14):472-484
Abstract Choice of Beacon.—The general question as to whether luminous or opaque signals should be used in ruling triangulation has recently been discussed in the Empire Survey Review (No.9, pp. 151–2 and No. 12, pp. 335–6). It may here be summarized that opaque beacons of suitable design are sufficiently accurate and offer the considerable advantages of being immediately available for subsequent work, of requiring little or no attention, and of being visible from all directions without rearrangement. Moreover, if of the tripod or quadripod type, they need not be dismounted during occupation of the station for observing, so that 0bservations by more than one observer are not interrupted. The only occasion for using luminous beacons arises from bad visibility, whether through atmospheric haze or lack of a suitable background or through the economic necessity of completing observations at night. These conditions are not peculiar to ruling triangulation. An ”all-round” type of luminous beacon—a pressure oil lamp or a rotating mirror system—can be used for nightwork or against a dark background, but single-direction luminous beacons are necessary to overcome haze. 相似文献
3.
《测量评论》2013,45(53):266-271
AbstractSince 1929 much of the primary triangulation carried out by the Geodetic Service of Canada has been preceded by an aerial reconnaissance of the areas: during this reconnaissance a tentative selection is made of station sites, and likely lines of sight are indicated. Varied types of topography have been covered—mountainous, rolling, flat wooded, mountain valleys. In most cases there were three common factors: the areas were well watered with lakes and rivers which permitted low flying in safety with pontoonor skii-equipped planes, ground transportation was difficult, and no contour maps existed. In some of the areas existing maps were very incomplete; of a few, reconnaissance aerial maps were available in which the planimetry was good; the better the map the easier the aerial reconnaissance. In all cases it was considered necessary that the air operations be checked by ground visits to the tentatively selected stations. 相似文献
4.
《测量评论》2013,45(7):34-44
AbstractIn June, 1931, a new start was made on the triangulation of Sarawak. The existing work consisted of a series of triangles measured in 1918–22, forming no rigid scheme and not capable of adoption or extension. A number of these stations were brought into the new scheme with either new beacons or the old repaired. The old stations embodied in the new scheme were: Serapi; Serambu (new bc.) ; Sejingkat (new ·bc.); Santubong (old bc. repaired); Satang; Undan (new bc.); Stapok; Sengai (new bc.); K. Rambungan; Salak (new bc.); Siol; Stabar. The new points established were: W. Base; E. Base; Sampadi (near old station); Buan Bidi; Selalang; Tundong; Serenggok; Bukit Satu; Kranje; Stigang; Golf-links; Bako. 相似文献
5.
《测量评论》2013,45(38):495-496
AbstractReports, appearing from time to time on the results of completed triangulation, show a variety of methods of construction of beacons. These range from temporary brushwood and calico signals to something of a more permanent nature. No doubt the purpose of the work, the type of country, local conditions, methods of observing, and finance, all enter into a decision as regards the necessity for the type of beacon to be used. 相似文献
6.
《测量评论》2013,45(12):335-340
AbstractFollowing recent discussions in the E.S.R. some experiences in Sarawak may be of interest.The argument for opaque beacons has been strengthened by the experience here of the past season, when combined day-and-night observing was carried out on the primary series, the daylight pointings being made to black-painted opaque beacons. No difference in the accuracy obtained by the two methods was noticeable in the results. Beacons were necessary in any case for the breaking down to secondary points. 相似文献
7.
《测量评论》2013,45(74):146-155
AbstractShortly after the inception of the Geodetic Survey of Canada in 1905, reconnaissance for primary triangulation was commenced in the Ottawa-Montreal area. About the same time, precise levelliilg operations were begun from a bench mark already established by the United States Coast and Geodetic Survey near the International border at Rouses Point in Quebec. 相似文献
8.
《测量评论》2013,45(9):151-156
AbstractMr. Clendinning's article on “Signal Lamps” (E.S.R., vol. ii, pp. 15–18) raises a point of major importance in geodetic triangulation. I entirely agree with him that the sole use of heliographs—heliostats to the purist—is in most parts of the world out of date. I also think, and indeed am prepared to state categorically, that the use of acetylene lamps is out of date and was out of date many years ago. The Americans, who are always worth listening to on the economics of surveys, would not otherwise have replaced all their acetylene gear by electric beacons. The answer, in my experience, and for reasons which I shall endeavour to make clear, is generally, but not necessarily always, to provide both helio and electric lighting; but first I should like to summarize the conditions in which luminous signals should be used at all. 相似文献
9.
Gary M. Young 《Journal of Geodesy》1974,48(4):349-363
For several years, geodesists have debated the proper role of electronic distances in modern geodetic surveys. The role must
be defined on an individual basis as a function of the desired accuracy and ultimate purpose of the survey. This paper proposes
a mixed mode of observations for the types of surveys currently being observed following conventional first-order triangulation
techniques. The mixed observational procedure requires only a portion of the survey control stations be instrument-occupied,
and directions and electro-optical distances be observed to the remainder of the stations. The method allows the substitution
of truck-or trailer-mounted portable towers, equipped with targets and reflectors, for a portion of the Bilby towers which
are presently required to provide theodolite observations from all primary control stations in a conventional triangulation
network. For the example considered, the mixed observational method provided more accurate position determinations than were
obtained using conventional triangulation.
Biographical Sketch Gary M. Young received his B.S. degree in Mathematics from Virginia Polytechnic Institute in 1965. In
the same year he joined the Triangulation Branch, Geodesy Division, National Ocean Survey (NOS), formerly the U.S. Coast and
Geodetic Survey, where he analyzed and adjusted horizontal control data. Mr Young received his M.S. degree in Geodesy from
Purdue University in 1970, and after completing further studies returned to the NOS in 1971. He is presently Chief, New Datum
Section, Control Networks Division, National Geodetic Survey, NOS. He is a member of ACSM and AGU. 相似文献
10.
《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
11.
《测量评论》2013,45(79):19-24
AbstractA problem frequently encountered by surveyors in carrying out a system of triangulation, is the adjustment of a network of lower order triangulation to make it geometrically consistent with an existing triangulation of a higher order. For example, in Fig. 1 it will be assumed that the positions of the stations A, B, and C have already been determined and that it is now required to determine the positions of the stations a, b, c, d, e and f from the measured values of the internal angles of the network of triangulation shown. In practice, several different solutions have been suggested, ranging from rigorous least squares methods to semi-graphical solutions. The method described in this article is believed to be original and may prove of interest to surveyors. 相似文献
12.
《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
13.
《测量评论》2013,45(88):86-87
AbstractThe usual procedure in breaking down a primary network of triangulation is to go through a secondary scheme to a system of tertiary points. These are usually of the order of 1½ imiles apart, and are the co-ordinated points to which the detail survey, of whatever kind it may be, is fastened. 相似文献
14.
《测量评论》2013,45(7):32-33
AbstractThe following note may be of interest to those responsible for or engaged in trigonometrical reconnaissance and observing, precise levelling, topographical mapping, and other branches of surveying where telescopes or field-glasses are used for long-distance work, especially when visibility is low. 相似文献
15.
《测量评论》2013,45(27):290-294
AbstractThe desirability of determining as accurately as possible the latitudes and longitudes of a number of points in Mauritius appears to have first appealed to the French astronomer M. L'Abbé de la Caille, who was sent to the island by the French East India Company in 1753. His observatory was situated 4,730 feet east and 2,610 feet north of Port Louis Time Ball, and in addition to determining the geographical position of this. 0bservatory (the house, later demolished, of a Mr Mabile, where Mr D'Après had made observations the previous year)—Latitude 20° 09′ 42″ S.; Longitude 55° 08′ 15″ E. of Paris—,he succeeded in effecting a triangulation of the island. Four bases were measured with wooden scales which previously had been compared with an iron toise (6.394 feet—the French fathom) approved by the Academy of Sciences, Paris; a I4-inch quadrant fitted with micrometer was used to measure the angles. 相似文献
16.
《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
17.
《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
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