AIR SURVEY AND COLONIAL CADASTRAL MAPPING

Abstract

Photogrammetry, terrestrial and particularly aerial, with which the following will exclusively deal, is at the present time employed practically throughout the world for the preparation of maps to every scale. While at the time of the introduction of the system its use was limited to topographical maps, it has been extended in the last fifteen years to the production of cadastral maps. In spite of the conservative. attitude of the cadastral authorities of every country to all innovations, this method has been accepted more and more by such authorities. After the excellent pioneer work of Switzerland, which in the course of time is to produce cadastral maps of half the country (2,000,000 ha.) by means of photogrammetry, Germany, Holland, France, Italy, Spain, and other countries have followed this example, the method being employed in these countries in an ever-increasing degree for cadastral measurement. Although the decision for the use of the photogrammetric method for cadastral measurement has been made in some degree in Europe, the large Colonies, especially those of the British Empire, are still hesitant in this connexion. Investigations which follow hereunder have been made in order to ascertain how far this new method of measurement is useful for Colonial cadastral measurement.     

A FIFTY-YEARS RETROSPECT

Abstract

The Ordnance Survey and the War.—I shall not inflict upon the readers of this Review any very long account of the work of the Ordnance Survey during the Great War. At that time the work of the Survey suffered from one necessary disadvantage: all the young men on its establishment, whether in the R.E. Companies or on the Civil Staff, left for active service. As a slight compensation for this inevitable dislocation all money difficulties in the preparation of maps for war disappeared.     

Specialist Maps Prepared by German Military Geologists for Operation Sealion: the Invasion of England Scheduled for September 1940

Abstract

During the Second World War, the German army developed the largest organization of any nation ever to contribute military applications of earth science in wartime. In the summer of 1940, its military geologists assisted planning for potentially the greatest amphibious assault to that time in history by preparing maps which analysed the terrain of southeast England in terms of coastal geomorphology, groundwater supply, quarry sites for construction materials and off-road trafficability. These specialist maps were generated at scales of 1:50 000, 1:100 000 or 1:250 000 by annotating topographical base maps, derived from the then current Ordnance Survey maps at most similar scale, with data derived from maps and memoirs published by the Geological Survey of Great Britain or larger-scale Ordnance Survey maps. They represent an early example of geotechnical mapping skills developed more fully in the German armed forces for operations elsewhere later in the war.     

THE LAY-OUT OF THE EAST AFRICAN ARC

Abstract

The 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.     

RADAR CONTROLLED AIR SURVEY PHOTOGRAPHIC OPERATIONS IN AFRICA 1946–1952

Abstract

In 1943, the Colonial Research Committee accepted a proposal submitted by the Colonial Survey and Geophysical Committee to the effect that a Central Colonial Survey Organization should be established to undertake geodetic surveys and topographical mapping, publish the work completed, hold the required equipment and maintain the necessary records. In order that such an organization, if approved, could commence to operate as soon as possible after the end of war, a detailed scheme for same was called for by the Colonial Research Committee.     

THE RANGEFINDER IN TROPICAL TOPOGRAPHICAL SURVEYING

Abstract

In text-books on surveying the rangefinder is usually dismissed in one sentence, which merely remarks on its inaccuracies and places in the category of scientific curios an instrument which should be most valuable to the plane-tabler in certain types of country. It is to combat this effect and to help topographers in their arduous work that these notes have been written. They are written from experience gained on topographical survey, on a scale of 1/125,000, in a tropical dependency where reduction of cost is of primary importance.     

AIR MAPS

Abstract

That special air maps might be necessary was realised as long ago as 1909 when the use of maps in connection with balloons was being discussed: but there was little progress and Bleriot's flight in the same year imposed a completely new outlook. At first, with the air speeds common in the early days, it was possible for the aviator to use standard topographical maps on scales such as half or one inch to one mile and navigate by the identification of prominent landmarks. It was soon realised however that certain features were more outstanding than others and this observation was incorporated in one of the very first attempts to produce an "aero" map made in 1912. In this the roads, railways and lakes were emphasised by hand colouring on a photoprint of the one inch Ordnance Survey sheet. The practice of using, or hand amending, existing topographical maps continued in the early days of the 1914-18 war but the growth of the R.F.C. and the R.N.A.S. emphasised the need for specific air maps. By the end of the war the R.N.A.S. had special air charts for use over the coastal areas of the British Isles, and a special aviation map of France had been produced for the R.F.C. These maps were probably the first ever made in quantity for use in the air but they did not differ radically from the existing topographical series except in the simplification of certain detail and the showing of additional data of value to the airman -aerodrolnes, landing grounds, dangers etc. Air speeds were still not very high and flying was largely confined to fine weather so that the main form of navigation continued to be by the direct reading of maps.     

CADASTRAL AIR SURVEY

Abstract

I Hope Dr Wolff's interesting article will stimulate to action some of those who have not given sufficient attention to air survey as a method of mapping or planning those areas which lend themselves to that method. At the same time, whether so many of us are as conservative as the author appears to think is a matter for doubt, and moreover we do not all look upon air survey as an “innovation”. As Dr Wolff writes from Palestine he might be interested to know that as the second British Officer to take up field survey work in the War in 1915—Major (now Brigadier) Winterbotham being the first—I was one of the earliest in my profession to study, and to assist in the development of, air survey. In 1915 our unit in the 3rd Army was the first to make use of air photographs for the production of a regular series of trench maps. There are consequently few surveyors more interested in the method. I have watched the progress of the science and the work of the Air Survey Committee with continued interest and have used air methods whenever these have been possible or suitable. On my last visit to Paris I tried my hand at plotting with a new instrument at the Service Géographique and was much impressed by the work that was being done.     

PHOTOGRAMMETRIC MAPPING IN SOUTH AFRICA

Abstract

This discussion relates to the use by the Trigonometrical Survey of South Africa of Wild photogrammetric equipment in the compilation of 1/18,000 topographical maps from 1/30,000 photographs and to the accuracy of the work found thus far by field check. The equipment used, the field and compilation methods and the specifications for the work are briefly described in this article.     

A FIFTY-YEARS RETROSPECT

Abstract

Early in 1902 I accepted with some misgivings the post of Instructor in Surveying at the School of Military Engineering, Chatham, in succession to Major A. C. MacDonnell. I had hardly joined at Chatham when Sir Thomas Holdich offered me the post of second in command of the Chile-Argentina Boundary Commission. However, my new chief, the Commandant, would not let me go, so I settled down to a few years of very pleasant work at Chatham. The first thing to do was to introduce a correct method of computing the geographical coordinates of the trigonometrical stations of a topographical survey, a matter over which my predecessor had suffered a rebuff. Now, however, the War Office personnel had changed; no opposition arose, and the thing was done.     

THE PLACE OF MOUNT EVEREST IN HISTORY

Abstract

The Himalaya are known as the highest mountains of the earth; but they have another title to fame not generally recognized in that they have been the home of civilized man for a longer period than any other mountain range. When the monoliths of Stonehenge were being raised in England and when the Pyramids were being built in Egypt, the glaciers of the Himalaya were being explored. The geographical names which are entered upon modern maps of the Central Himalaya are very ancient memorials of civilization. The existence of a mountain nomenclature, Aryan in the west and centre, Mongolian in the east, has given rise to linguistic problems not less difficult than the topographical problems of the snows. In 1927 the volumes of the Linguistic Survey of India were published; they had been written by Sir George Grierson, an officer of the Indian Civil Service, and they dealt with 723 different languages and dialects. In the Himalaya there are now in use among the peoples seventy different languages, all of which (with one aboriginal exception) belong either to the Aryan or Mongolian family. Languages are historical monuments, and from them Sir George Grierson has been able to decipher the outlines of history.     

A FEW THOUGHTS ON MAP CONSTRUCTION

Abstract

Few realize that more branches of human knowledge contribute to the production of a topographical survey sheet than to any other single object that could be named off-hand. We have made great strides since the days of Swift: elephants, whales, etc., are no longer regular cartographical features. From astronomy to chemistry science plays an increasing part, while art tends to languish. Some there are who love the old styles and ornamentation; yet the latter assort ill with ample and accurate data.     

A SIMPLE FORM OF CATENARY APPARATUS FOR MINOR CONTROL TRAVERSES IN ROUGH COUNTRY

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.     

大比例尺地形图更新问题探讨

近年来,城市发展变化非常快,地形图更新滞后于城市发展,研究城市大比例尺地形图更新问题很有必要。本文阐述了地形图更新的方法,主要有数字摄影测量更新、利用高分辨率遥感影像更新、数字化测图更新以及借助其它项目资料进行更新等方法,并探讨了城市大比例尺地形图更新周期问题。     

THE APPLICATION OF AN INFRA-RED FILTER TO SURVEYING INSTRUMENTS

Abstract

The 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.     

MAP MAINTENANCE,POLICY AND TECHNIQUE

Abstract

Introduction.—Although much has been written on the various branches of surveying, few text-books do more than give the problem of Map Maintenance a passing mention. It is true that probably the major problem of the surveyor, when considering the world as a whole, is the urgent need of any sort of accurate map for most of its surface, yet at the same time quite considerable areas have already been surveyed, and the maintenance of these areas forms a very formidable problem in itself. Moreover, it is not generally realized that problems of maintenance necessitate a complete reorientation of technical outlook in comparison with questions of an initial survey. Clearly, when maps are being made in the first instance, the primary requirement is an adequate framework, whose main essentials are accuracy; rigidity and permanence. The filling in of the topographical detail and the final reproduction are matters of necessarily secondary importance. Furthermore, as the time required for the field work is large in comparison with the office stages, there is little actual or apparent gain in reducing the time taken on drawing and reproduction. In these circumstances the problem of an initial survey is essentially mathematical in its technique, little attention being required for the final stages of drawing and reproduction, which can be carried out, by craftsmen, at the unhurried pace which it has been their privilege to maintain in the past.     

BOWDITCH TRAVERSE ADJUSTMENT AND A MODIFICATION

Abstract

Cadastral Traversing.—For cadastral purposes traverses are now being executed with an accuracy wholly unnecessary for even large topographical scales. But since “accuracy” varies from a mile to a micron, according to the viewpoint of the observer, it is advisable to exhibit a cadastral traverse, care being taken that it is not an example of that not very uncommon occurrence in which fortuity apes precIsIon. If the accuracy of the example is somewhat unusual, it can be said with assurance that it is not very unusual.     

SOME NOTES ON COMPUTING

Abstract

Probably the most important matter connected with computing is checking. Far more time is wasted by an incorrect result which has been passed as correct by the checker than by any other fault in computing. It is not necessary that a computer should always be perfectly accurate, but it is necessary that the method of checking used should always detect his errors. If the computer is sure that his accidental errors will be picked up he is relieved of anxiety and his work will be quicker and eventually more accurate for that reason.     

Mapping for Cycle Touring in Britain; Past,Present, and a Possible Future

Abstract

The Lack hitherto of studies of cycle-touring mapping in Britain is noted, and some basic attributes of cycle touring, including speed, daily distance, gradients and wind, are described. Essential and desirable qualities for a cycle-touring map are enumerated, including the need to depict all rural routes available to cyclists; it is concluded that the optimum scale is in the range 1:100 000–1:126 720, and that relief should by contours at an interval not greater than 30 metres. National mapping in the optimum scale range which were published after 1945 are then reviewed, and reasons suggested as to why none has been kept in print. The mapping available for cycle touring in Britain in 2001 is Ordnance Survey (OS) 1:50 000 Landranger series contains all the necessary information, it is too bulky to be suitable; and that most of the other maps published in the optimum scale range have inadequate relief information and all offer very limited geographical cover. The potential competition for the OS 1:50 000 from a national map series in the optimum scale range is acknowledged, and an outline specification for a 1:125 000 series is described, which seeks to minimize that competiton whilst providing all the necessary information for cycle touring.