摘要:

AbstractIn order to obtain the individual directions of the paths to the satellite, the ray bundle defined by the corrected photo co-ordinates and the focal length of the camera must be converted by a space transform into the“passpoint”system of the fixed stars given by the right ascension/declination system. This problem of the spatial rotation of a ray bundle has been much examined in photogrammetry in recent years. We refer the reader to the comprehensive index of literature contained in [49].

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.154

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractIt is a known fact that the accuracy of short bases measured in triangulation is soon lost in base extension nets. Additional degradation occurs as the net is extended, with the result that the scale error between two adjacent fixed stations may amount to 20 parts per million, which is much worse than what is expected from direct measurements with modern instruments. When subsidiary control is extended from the prjmary net by pure triangulation the error of the fixed scale will persist throughout the new network but a uniform scale error will not, by itself, cause figural distortions. If the new network is extended by trilateration or by“triangulateration”(a term used by Dixon [2]), figural distortions may become serious unless the conflict between the fixed scale and the scale of length measurelnents is identified and resolved. Dixon [2]deals with this problem by including a scale correction unknown in combined adjustments of angles and tellurometer lengths by the method of conditions. This paper discusses the fundamentals of the use of the scale unknown in adjustments by variation of coordinates and gives examples of the effect of fixed scale error on the adjusted results.

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.164

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractIn a recent issue of theSurvey Review(Vol. XIX No. 149, July 1968, pp.317–318) Mr. A. L. Allan described a“high subtense bar”whose rotation about a vertical axis is effected by“an assistant pulling on two strings”. Some years ago a remote controlled subtense bar was devised in the workshop of this Department and is briefly described and illustrated by photographs in this article.

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.170

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractSince the development of the first electronic distance-measuring device in 1948, the practising surveyor has been awaiting the day when electronics could provide him also with a modern, inexpensive means of measuring, quickly and simply, the numerous short distances measured hitherto by repetitive laying-out of a tape. Until now, micro-wave equipment has not yet been suitable, as it always involves the use of an active reflector, which is nothing less than a second transmitter/receiver unit, identical therefore also in weight and price. However, the vital requirement in low order survey using mostly the so-called polar, or bearing and distance method is onlyonemaster station and, above all, light and cheap targets. The electro-optical distancers are already much better suited for short ranges, as they operate with the aid of co-operative reflectors, such as plane mirrors or reflecting prisms. Here, however, the difficulty centres firstly around the modulation of the light waves, which is critical in a small unit, and, in addition, requires much power and, secondly, in the fact that visible incoherent light is used as a carrier wave, which is affected by strong absorption and dispersion. In addition, outside light, especially when measuring in the direction of the Sun, produces a very high noise level, thus this type of instrument gives more range by night than by day.

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.173

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractA discussion of the geometrical principles of methods of fixing positions under water by means of distances calculated from travel-times of acoustic signals.

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.183

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractThe ceremony on May 1st, 1969, at the official opening of the new buildings for the Ordnance Survey at Southampton was referred to in our last issue. The two speeches made on that occasion are printed below, and an air photograph of the new buildings is seen on the plate opposite this page.

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.196

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.197

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.198

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

ISSN:0039-6265    

DOI:10.1179/sre.1969.20.154.200

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor