MAPPING OUT OF CROWN LANDS IN CEYLON

Abstract

13. As mentioned earlier (xi, 83, 199) the “Final Village Plan”, which is evolved from the 4-chains-to-an-inch (1:3,168) “Block Survey” village plan after inquiry and settlement of claims as between the Crown and private parties, provides a sound basis for mapping-out and for the subsequent administration of the Crown estate. But as (in all cases) the development of Crown land could not await Block Survey and “Settlement”, it was also necessary to undertake mapping out in areas which had not been systematically surveyed, and for which no continuous large-scale plans were available.     

SOUTHERN RHODESIAN MILITARY SURVEYORS IN THE WORLD WAR, 1939–1945

Abstract

For some two months prior to the formation of the two companies, an intensive course of survey training and “refreshing” had been undergone by all ranks in the field sections, culminating in a combined Royal Artillery/Royal Engineer survey exercise from 1st to 10th October, carried out under operational conditions in all respects (even down to a 30-hour non-stop period of “photo-topo” compilation for the map on which the “final shoot” took place).     

ON THE CLASSIFICATION OF MAP PROJECTIONS

Abstract

1. Classes and Varieties. A map projection can be considered from different points of view, each such point of view representing a “class” of projections. The classes, in their turn, are subdivided into “varieties”.     

PRACTICAL APPLICATION OF THE LAPLACE LONGITUDE-AZIMUTH RELATION TO CONTROL OF GEODETIC ANOMALIES

Abstract

1. In geodetic work a ‘Laplace Point’ connotes a place where both longitude and azimuth have been observed astronomically. Geodetic surveys emanate from an “origin” O, whose coordinates are derived from astronomical observations: and positions of any other points embraced by the survey can be calculated on the basis of an assumed figure of reference which in practice is a spheroid formed by the revolution of an ellipse about its minor axis. The coordinates (latitude = ?, longitude = λ and azimuth = A) so computed are designated “geodetic”.     

Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

ABSTRACT

Conceptually, 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.     

Field Techniques in Remote Sensing: Learning by Doing

Abstract

The paper summarizes one professor's observations and resulting approach to teaching a semester‐long course on the subject of field techniques as they relate to remote‐sensing campaigns. The text describes how a “learning‐by‐doing strategy” is applied to such a course. More specifically, the paper describes how the instructor requires students to design, construct, and actually implement “hardware solutions” to problems involving collection of spectral (and ancillary) data in the field. Pupils must test their developed methodologies and “technological creations” with regard to a focused research problem undertaken in a difficult field setting during a week‐long outdoor experience. The students are expected to evaluate, and possibly modify, their methods and procedures “on‐the‐fly.” Individual group research problems, methods, and hardware solutions are briefly described, and selected student evaluations of the experience are provided.     

SURVEY IN THE GREAT WAR

Abstract

Artillery Survey.—Included in the term “Artillery Survey are two distinct problems, the first that of determining the “line” and “range” at which fire should be opened, and the second that of laying the gun in the required line. To appreciate these problems it. is necessary to know a little about the technique of gunnery, and for the benefit of those who have no acquaintance with the subject the following brief résumé may be given.     

BATTLE SONG OF THE FAR-FLUNG SURVEYORS

Abstract

Air.—Any good Guest Night tune which happens to fit to a first order, and remains more or less in tune after subsequent orders. “Coming down the Mountain” and “Kabul River” would do.     

FURTHER NOTES ON FIGURES OF REFERENCE

Abstract

Major Hotine (E.S.R., No. II, pp. 264–8) still finds the location of a reference spheroid to offer insuperable difficulties. I confess that my difficulty is to see his! In my previous article (E.S.R., No. 8) at the foot of page 76, I used the word “coincidence” in error for “parallelism”. This harmonizes the article and I am glad that Major Hotine has directed attention to the error.     

A NOTE ON AZIMUTH DETERMINATION

Abstract

The purpose of this note is twofold; first, to criticize the “azimuth” section of the paper “Some Notes on Astronomy as Applied to Surveying”, by R. W. Pring (E.S.R., July 1952, xi, 85, 309–318),and secondly, out of these criticisms to develop an alternative method of making observations for azimuth. It will be apparent that this method owes much to the ideas put forward by Mr. Pring.     

THE NOMENCLATURE OF MAP PROJECTIONS

Abstract

Map 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.     

A PLEA FOR THE EXPANSION OF THE SCOPE OF THE DOMINION AND COLONIAL SURVEY DEPARTMENTS

Abstract

In the remarks which follow, the word “scope” will have the meaning given in the Concise Oxford Dictionary—“Sweep or reach or sphere of observation or action, extent to which it is permissible or possible to range, opportunity, outlet, vent”. Another good definition is “field of action”. The object of the paper is to show that greater efficiency will be obtained if all types of survey work in a country, except possibly railway surveys, are done under the supervision of, or by the staff of, a Survey Department of wider scope than is normal.     

THE HYDROGRAPHIC DEPARTMENT OF THE ADMIRALTY: (I) HISTORY AND ORGANIZATION

Abstract

The Hydrographic Department of the Admiralty performs a number of functions appropriate to its status as an Admiralty Department but it is also responsible through its head, the Hydrographer of the Navy, for the compilation, publication and distribution to the Merchant Navy and the public, as well as to the Fleet, of Admiralty charts and of other nautical publications concerned with the safety of navigation. The latter comprise the “Admiralty Sailing Directions”, the “Admiralty Tide and Tidal Stream Tables”, the the “Admiralty List of Lights” and the “Admiralty List of Radio Signals ”.     

BASE MEASUREMENT IN THE ANGLO-EGYPTIAN SUDAN

Abstract

60. The three standard or field reference tapes are stored at the N.P.L., Teddington, and standardised to class “A” accuracy immediately before and after each base measurement. In order to reduce the residual contraction or “creep” of in var when exposed to higher temperatures, the tapes are retained for as short a time as possible in the Sudan and since 1945 they have been transported in both directions by air. In this way, any “creep” should be revealed by the standardisation after a measurement. From the formula of Dr. Guillaume the ultimate shortening, in the temperatures prevailing at Meheisa and Husheib, would have been ?26 and ?20 × 10^?5 ft. respectively and it is clear from Table 3 that this tiresome source of uncertainty is largely eliminated by the procedure adopted.     

THE ERRORS IN A RADIAL LINE PLOT OF AIR PHOTOGRAPHS

Abstract

Lieut.-Col. Browne's interesting method of combii1ing radial line plots (“The Application of Transformation Factors to the Adjustment of Air Photographs”, E.S.R., x, 73, 119-130) depends for its success on the basic accuracy of the radial line plots of the individual air photo strips. It therefore poses the very interesting question: What accuracy can we expect in a graphical radial line plot?     

THE TRANSVERSE MERCATOR PROJECTION

Abstract

I. Introduction.—Map projection is a branch of applied mathematics which owes much to J. H. Lambert (v. this Review, i, 2, 91). In his “Beyträge zum Gebrauche der Mathematik und deren Anwendung” (Berlin, 1772) he arrived at a form of projection whereof the Transverse Mercator is a special case, and pointed out that this special case is adapted to a country of great extent in latitude but of small longitudinal width. Germain (“Traité des Projections”, Paris, 1865) described it as the Projection cylindrique orthomorphe de Lambert, but he also introduced the name Projection de Mercator transverse or renversée; he shows that Lambert's treatment of the projection was remarkably simple.     

COMPENSATION OF TRAVERSES WHEN LENGTHS ONLY ARE CORRECTED

Abstract

If it be assumed that the linear measurements of traversing are alone afflicted with error, the method of distribution of error demands consideration. In the present paper the notation of Wright and Hayford will be followed (“Adjustment of Observations”, 1906 edn., p. 156).     

UNDER FIVE SOVEREIGNS: OR MILITARY SURVEYS FOR THE LAST FIFTY YEARS

Abstract

In Close's “Text-book of Topographical Surveying” there still appears, as Plate XVII, a specimen of small-scale plane-table work in Somaliland. It dates back to 1903. In the first edition of the Text-book, which to the joy of all soldier surveyors replaced the “Manual of Military Topography”, the letterpress referring to Military Surveys dealt entirely with rapid small-scale mapping and with hasty triangulations.     

REWEBBING DIAPHRAGMS WITHOUT TEARS

Abstract

Every student of Close and Winterbotham's “Text Book of Topographical Surveying” learns that rewebbing diaphragms is a simple job. Unfortunately, when circumstances compel a surveyor to reweb a micrometer diaphragm in the field, he is liable to find, after some years in the tropics, that fever (and one thing and another) have played havoc with the steadiness of hand and eye. Under present conditions young surveyors who have been trained on optical micrometers may find themselves using 5″ micrometer theodolites with over a dozen webs, anyone of which is liable to sag, break or develop whiskers, while even a “Tavi” may conceivably remind the user that it has one web.     

RUN OF THE BUBBLE

Abstract

Old text-books in English frequently referred in very loose terms to the “run of the bubble”. The meaning of the term was often so doubtful as to leave the impression that the writers themselves had vague notions on the theory of the level; certainly they must have left the student often in a state of bewilderment. In the sense in which it was used the phrase “run of the bubble” appears to have been intended to suggest a line parallel to the directrix.