German Maps and Survey on the Western Front, 1914–1918

Abstract

Fighting the 1914–18 war largely on enemy territory in both the east and the west, German was at a disadvantage compared to the Allies when it came to survey and mapping as it did have access to much of the geodetic, topographic and cartographic data, relating to this terrain, necessary for modern warfare — in particular for artillery survey. German and Austria did, however, have a commanding lead in terrestrial and aerial photogrammetry, and the latter was to prove crucial in the production of accurate large-scale maps of enemy and occupied territory. Despite strong forces of conservatism in the high and field commands and in the artillery and military survey organizations, new air survey methods based on the photogoniometer and radial triangulation were rapidly developed. Through continual laboratory and field experimentation and testing, German was to increase her lead in aerial photogrammetry, and by the end of the war had not only set up a completely new air survey organization but was developing a new generation of optical-mechanical stereoplotting instruments of great precision. German progress was not, however, evident in all fields of military survey, and this paper examines the approaches taken by German to survey and mapping on the Western Front, and briefly compares and contrasts them with those of the Allies.     

THE NAMING OF THE STARS

Abstract

We have seen that a few constellation-names used by us to-day make their appearance as far back as the Homeric poems, while the star-names Sirius and Arcturus are found in the works of Hesiod. We saw no reason to suppose that these early poets knew no names for other groups. They mentioned only those conspicuous heavenly objects that might occur in any general literature, as for example in the Old Testament books of Job and Amos. There are sporadic references to constellations in the extant works of the great Greek tragedians of the fifth century B.C., but these give us few additions to the Homeric list'. It is not till we come to the special literature of the subject that constellation-names appear in any quantity. The first specialist whose name stands out is the mathematician Eudoxus of Cnidus, a disciple of Plato, who lived in the first half of the fourth century B.C. He wrote a prose work entitled the “Phaenomena”, which, though unfortunately lost, was rendered into verse by the poet Aratus about 275 B.C.     

Fourier geoid determination with irregular data

The fast Fourier transform (FFT) and, recently, the fast Hartley transform (FHT) have been extensively used by geodesists for efficient geoid determination. For this kind of efficiency, data must be given on a regular grid and, consequently, a pre-processing step of interpolation is required when only point measurements are available. This paper presents a way of computing a grid of geoid undulations N without explicitly gridding the data. The method is applicable to all FFT or FHT techniques of geoid or terrain effects determination, and it works with planar as well as spherical formulas. This method can be used not only for, e.g., computing a grid of undulations from irregular gravity anomalies g but it also lends itself to other applications, such as the gridding of gravity anomalies and, since the contribution of each data point is computed individually, the update of N- or g-grids as soon as new point measurements become available. In the case that there are grid cells which contain no measurements, the results of gravity interpolation or geoid estimation can be drastically improved by incorporating into the procedure a frequency-domain interpolating function. In addition to numerical results obtained using a few simple interpolating functions, the paper presents briefly the mathematical formulas for recovering missing grid values and for transforming values from one grid to another which might be rotated and/or scaled with respect to the first one. The geodetic problems where these techniques may find applications are pointed out throughout the paper.Presented at theIAG General Meeting, Beijing, P.R. China, Aug. 6–13, 1993     

Detection of station coordinate discontinuities within the Italian GPS Fiducial Network

The Detection Identification Adaptation (DIA) procedure was applied to the coordinate time-series of some permanent GPS stations belonging to the Italian GPS Fiducial Network (IGFN), of the Italian Space Agency (ASI), to detect discontinuities and to reject outliers. The daily solutions of the stations of Cagliari, Genoa, Medicina, Noto, Turin, Perugia and Venice were computed for the period 1997.0–2003.0 using Bernese GPS software v.4.2. The data were interpolated using a model with a linear term and an annual periodic term. The parameters were estimated by least squares. The DIA procedure was organized to automatically detect discontinuities and outliers. Approximately, 70% of the discontinuities present in the coordinate time-series were identified and their magnitudes were estimated. The identified discontinuities are basically caused by equipment replacement and reference frame changes, but in a few cases the reason is still unknown. With regard to the outliers, roughly 6% of the data were rejected. These data were considered outliers on the base of the level of significance and of the power of the test adopted in this work. Except for the stations of Perugia and Venice, the estimated coordinates agree with ITRF2000 values at the 10 mm level, and the estimated velocities are within a few mm/year of the ITRF2000 values.     

THE MERCATOR PROJECTION AND THE RHUMB LINE

Abstract

Introductory Remarks.—A line of constant bearing was known as a Rhumb line. Later Snel invented the name Loxodrome for the same line. The drawing of this line on a curvilinear graticule was naturally difficult and attempts at graphical working in the chart-house were not very successfuL Consequently, according to Germain, in 1318 Petrus Vesconte de Janua devised the Plate Carree projection (“Plane” Chart). This had a rectilinear graticule and parallel meridians, and distances on the meridians were made true. The projection gave a rectilinear rhumb line; but the bearing of this rhumb line was in general far from true and the representation of the earth's surface was greatly distorted in high latitudes. For the former reason it offered no real solution of the problem of the navigator, who required a chart on which any straight line would be a line not alone of constant bearing but also of true bearing; the first condition necessarily postulated a chart with rectilinear meridians, since a meridian is itself a rhumb line, and for the same reason it postulated rectilinear parallels. It follows, therefore, that the meridians also must be parallel inter se, like the parallels of latitude. The remaining desideratum—that for a true bearing—was attained in I569 by Gerhard Kramer, usually known by his Latin name of Mercator, in early life a pupil of Gemma Frisius of Louvain, who was the first to teach triangulation as a means for surveying a country. Let us consider, then, that a chart is required to show a straight line as a rhumb line of true bearing and let us consider the Mercator projection from this point of view.     

卫星双向共视法时间比对中Sagnac效应计算模型

根据卫星双向共视法进行时间比对的基本原理,详细介绍了Sagnac效应产生的原因。并以圆轨道地球静止同步卫星为例,推导了卫星双向共视法时间比对中Sagnac效应在地心惯性系的基本计算模型。给出了当地面站在赤道上和不在赤道上这两种情况下,Sagnac效应的详细计算过程。     

THE EUROPEAN ORGANISATION FOR EXPERIMENTAL PHOTOGRAMMETRIC RESEARCH (OEEPE)

Since the occasion of the Thompson Symposium in 1979, two new members have joined OEEPE. These are France and the United Kingdom. The possibility of membership had been considered by the UK over the last decade on more than one occasion but, for one good reason or another, no application had been made. In 1980, however, W. P. Smith (Director General, Ordnance Survey) circulated organisations and individuals who might be interested and received an almost unanimous expression of support for an application for membership. This was also in line with the Ordnance Survey's intent to increase its links with other organisations, both nationally and internationally. The Foreign Office agreed that the UK should apply for membership and this was done. The UK became a full member of OEEPE in time for the Oslo meeting of the Steering Committee in 1981.
There follows a background paper on the work of OEEPE and accounts of current OEEPE Commission activities.     

Scale and orientation in combined Doppler and triangulation nets

Summary In a combined Doppler and terrestrial net adjustment not only the known systematic discrepancies in scale and orientation between the Doppler measurements and the terrestrial results must be modelled, but also all available informations about the accuracy of these systematic differences are to be taken into account. Using the Helmert-block method for the combination procedure, no covariance matrices for the terrestrially determined coordinates must be computed, their numerical evaluation being a computational detour. The proposed procedure as applied to real nets, includes all different kinds of geometric or physical models, whereby their specific parameters are eliminated at this level. Two solutions are discussed, a three-dimensional and a two-dimensional one, but “two-dimensional” is not equivalent to “non-spatial” in this context.     

The Photogrammetric Society Analogue Instrument Project: A Sixth Extract

The paper entitled The Photogrammetric Society Analogue Instrument Project was published in The Photogrammetric Record, 14(82): 565-582 and contained, as Appendix A, an extract from the Archive concerned with the history of the Zeiss Stereoplanigraph in Great Britain. Further extracts have appeared in each of the subsequent issues.
This extract, the sixth of the series, completes the history of the use of the various types of Wild instrument in the United Kingdom. It is concerned with the later post-war instruments, in numerical order, from the A7 Autograph to the A10 and therefore includes a note on one of the most popular and successful analogue plotting instruments ever produced, the Wild A8 Stereoplotter.
At the moment, none of the instruments dealt with in this extract appear to be under immediate threat. However, their role as production instruments is fading fast in most organizations but they are being retained, often for training purposes.
The Archive contains no mention of the last and most refined range of analogue instruments produced by Wild as their Aviomap (AM) series. With the benefit of hindsight it is now obvious that, at the time of their introduction, the transition from analogue to analytical techniques was about to take place at an accelerating pace. There is therefore no entry in the Archive for any AM or AM-U instrument; none (or perhaps only a very few) seem to have been imported into the United Kingdom.     

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.     

Calibration facility for airborne imaging spectrometers

A new facility designed to perform calibration measurements of airborne imaging spectrometers was established at the German Aerospace Center (DLR) in Oberpfaffenhofen. This Calibration Home Base (CHB) is optimized to characterize radiometrically, spectrally, and geometrically the APEX (Airborne Prism Experiment) imaging spectrometer, which is currently being developed under the authority of the European Space Agency (ESA). It however can be used for other optical sensors as well. Computer control of major laboratory equipment allows automation of time consuming measurements. In APEX configuration (wavelength range: 380 to 2500 nm, instantaneous field of view: 0.48 mrad, field of view: ±14) spectral measurements can be performed to a wavelength uncertainty of ±0.15 nm, geometric measurements at increments of 0.0017 mrad across track and 0.0076 mrad along track, and radiometric measurements to an uncertainty of ±3% relative to national standard. The CHB can be adapted to similar sensors (including those with thermal infrared detectors) by exchanging the monochromator’s lamp, the gratings and the filters, and by adjusting the distance between the sensor and folding mirror.     

A graph-theoretical algorithm for detecting configuration defects in triangular geodetic networks

Summary The problem to detect configurational defects in geodetic networks is solved by a graph-theoretical algorithm, here applied to triangular geodetic networks and being presented as a computer program in the Appendix. Based on an analysis of the incidence matrix the algorithm detects, for instance, missing vertical directions which cause two types of deficiencies. In case of only vertical direction measurements from one point to another, but no counter vertical direction measurements backwards, the rank deficiency of the first type is identified. Furtheron if there are “bare” points with no vertical direction measurements at all, the rank deficiency of the second type is found. The algorithm has proved a rank deficiency of 4+13=17 in theSW Finland triangular network which before has been found as the surprizing rank defect ofTAGNET 3d-operational adjustment.     

Comparative Study of Stereoscopic Techniques Applied to a Virtual Globe

Abstract

For years, stereoscopy has been related to photogrammetry in topography. However, these methods are not efficient for virtual globes because the effect is only visible from one view point and this restricts interactivity. By using synthetic image techniques in order to generate stereo-paired images, we can produce visible effects from any view point. In this paper, we present a comparative study of stereoscopic techniques in virtual globes supported by a test carried out among 51 participants. Three devices were used: anaglyphs, an autostereoscopic screen and a quadbuffer system. The aim was to determine which one of the three devices causes a deeper feeling of immersion and which one can be more efficient in a virtual globe. Results show considerable differences between the quadbuffer system and the other devices. The mentioned system causes in the user a stronger feeling of depth and immersion in the virtual globe.     

CURVATURE AND REFRACTION TABLES FOR TOPOGRAPHICAL SURVEYS

Abstract

In a series of articles published at different times in the Empire Survey, Review, the writer has stressed the utility of the slide rule in topographical work for both mapping and engineering purposes. It is his opinion that every topographical surveyor should be thoroughly conversant with the slide rule, and that there is no difficulty in teaching anyone, even with limited educational qualifications, all that is necessary about if. One advantage of its use is that the plotting-scale divisions need not represent any simple multiple or fraction of the normal units of length, but can be chosen so that the subdivisions cause no undue eye strain. This plotting scale can then be used for work on any scale, all necessary tables being calculated and constants adopted for use with it, without any extra work being required. A scale of I/250 (I foot divided into 25 main and 250 minor divisions) was found to meet the case.     

THE ORDNANCE SURVEY AND THE FINAL REPORT OF THE DEPARTMENTAL COMMITTEE OF 1935

Abstract

The conclusions of this Committee have aroused small interest so far, because war was upon us almost as soon as the publication (1938). They may, however, greatly affect our surveys and maps of the future, and it is time to examine them. First of all, however, it is desirable to see the background against which the Committee's recommendations appear. For that reason the following chronological summary is given. It is divided into three periods, those of Growth, of Hesitation and of War, and it is given to supplement the chronology of the Final Report in matters which are discussed therein.     

A STELLAR PROGRAMME FOR TIME OBSERVATIONS

Abstract

A GOOD deal of astronomical work was called for during the operations of the British Somaliland–Ethiopia Boundary Commission. The method employed by the British Section for the determination of local time being that of star altitudes in the prime vertical, after the first few stations had been occupied the suggestion was made that the observer could be saved considerable strain by the preparation of a programme for time observations, much on the same lines as for latitudes. The proposal was tried, proved eminently successful, and became a standard part of the British Section's procedure. An example of such a programme is given below. I t is a little laborious, but simple.     

THE WASHINGTON (1939) CONFERENCE OF THE UNION OF GEODESY AND GEOPHYSICS

Abstract

For the first time in the Western Hemisphere the Union met in conference in Washington between the dates 4th and 15th September 1939. Though rumours of indefinite postponement were current in the Press, there was never any intention that the Conference should not be held according to plan, which action was supported throughout by the State Department, without whose effective co-operation the event could not have succeeded. The fears of world-wide cataclysm, too soon turned into grim reality, no doubt influenced the attendance of European delegates; but the influx of representatives of the United States and Canada was correspondingly greater, and contributed to the success of the assemblies. In a sense the Conference gained by the reduction of members, for more time was available for the cultivation of former acquaintanceships; moreover, in the fraternizing of the European delegates with American scientists an opportunity was given to reveal the individuality behind well-known names, which helps so much towards mutual understanding.     

A SIMPLIFIED ANALYTICAL METHOD FOR THE ADJUSTMENT OF AERIAL TRIANGULATION

Abstract

This method, which has been used in connection with Wild A5 and A6 stereoplotting machines, was developed in an endeavour to retain as many as possible of the advantages of the analytical method without incurring the corresponding disadvantage of excessively lengthy computation. It is capable of being quickly learnt by even an inexperienced computer, and adequate checks on the accuracy of the numerical work are easily applied where not automatically provided. It has the advantage over the graphical method formerly used, that no control point is accepted as more reliable than another, equal weight being given to all, and an indication of the relative reliability of the individual control points is furnished by the table of residual errors obtained.     

UNDERWATER PHOTOGRAMMETRY IN THE NORTH SEA

Underwater photogrammetry is being used in the particularly hostile environment of the North Sea where it has been put into commercially viable operation. The authors discuss underwater photogrammetry related to other means of inspection of oil platforms. They also deal with operational experience of 35 mm and 70 mm cameras, camera calibration, the provision of control and photogrammetric observations and data analysis. The demand for underwater photogrammetry continues to grow.