SOUTH AND EAST AFRICA AND THE INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS

Abstract

THE resolutions and pious hopes (væux) passed by the International Union of Geodesy and Geophysics at Edinburgh in September 1936 have just been circulated in a formidable document of 8 pages and XXIX commandments. Of these, two affect the Cape-to-Cairo line particularly and they seem to deserve special study. The first of these, Number III—on systems of Projections—applies the meridional strips of the Transverse Mercator Projection apparently to all maps, topographical as well as cadastral.     

THE INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS AT LISBON

Abstract

On the 17th September, 1933, the Fifth General Assembly of the International Union of Geodesy and Geophysics was opened by General Carmono, President of the Republic of Portugal, in the hall normally occupied by the Portuguese Parliament at Lisbon. Great Britain sent to this meeting of the Union twenty-two delegates, of whom the majority travelled to Lisbon by the S.S. Arlanza.     

THE INTERNATIONAL UNION OF GEODESY AND GEOPHYSICS, 1948

Abstract

The 8th general assembly of the International Union of Geodesy and Geophysics (lUGG) took place in Oslo by invitation of the Norwegian National Committee. A considerable number of delegates had arrived by the 17th August, for which day preliminary meetings of the Executive Committees and Councils of the Union and of the several Associations were arranged. The formal opening in the Aula of Oslo University began at 10.30 on the 19th. It was honoured by the presence of H.M. the King of Norway.     

A FIFTY-YEARS RETROSPECT

Abstract

On returning from Central Africa I was posted, for ordinary duty, to Edinburgh, and after a short time I found myself again on the Ordnance Survey. Late in 1899 the South African War broke out, and early in 1900 I was sent out to South Africa in command of a very small Field Survey Section. But before describing the limited activities of this Section it may be as well to give some idea of the attitude of the higher civil and financial authorities towards the proposition that it is desirable to be prepared with maps of possible theatres of war.     

Characterizing European urban settlements from population data: a cartographic approach

ABSTRACT

The cartographic identification and characterization of urban settlements is problematic, particularly in varied areas or in large geographical extensions. This is due to the divergence between morphological area structures and data attribution, which is generally available at the level of administrative units. Most existing experiences focus on small regions or use indirect data, from which only indirect information can be derived. This paper proposes an identification of urban settlements in the European Union space, which combines urban population and shape through geographic information system (GIS) techniques. For that purpose, 1 km² cells with associated population data are used. A procedure is developed establishing three different types of urban settlements, according to population and population density values: high-density urban clusters, small and medium-sized towns, and very small towns. A validation of this procedure is performed using direct survey from local experts in 10 selected study areas. The final results show that 78,307 urban settlements can be identified: 88.17% of them are classified as “very small towns,” 10.75% as “small and medium-sized towns,” and 1.08% as high-density urban clusters. This exercise generates new information for the European Union and surrounding countries, and yields the basis for further research. All GIS operations are performed using vector layers, which is not usual in large-area regional studies.     

Society Record

Abstract

Since the emergence of newly independent states from the former Soviet Union, there has been a much more liberal approach to the publication of maps. Types and scales of maps which had formerly only been available to the military or planners are now being freely sold to the general public and to foreigners. Freed from the straitjacket of military requirements and censorship, a number of the former Soviet republics are also producing a much wider range of map types. This paper explores both the types of maps produced in the former Soviet republics and those being produced under the new, sometimes more liberal regimes.     

General Meeting of IAG

Informations

General Meeting of IAG 3–12 August 1989, Edinburgh, Scotland, U.K.     

A European perspective on Digital Earth

Abstract

The purpose of this paper is to contribute to the definition of a European perspective on Digital Earth (DE), identify some actions that can contribute to raise the awareness of DE in the European context and thus strengthen the European contribution to the International Society for Digital Earth (ISDE). The paper identifies opportunities and synergies with the current policy priorities in Europe (Europe 2020, Innovation Union and Digital Agenda) and highlights a number of key areas to advance the development of DE from a European perspective: (1) integrating scientific research into DE; (2) exploiting the Observation Web with human-centred sensing; and (3) governance, including the establishment of stronger linkages across the European landscape of funding streams and initiatives. The paper is offered also as a contribution to the development of this new vision of DE to be presented at the next International DE Conference in Perth, Australia, in August 2011. The global recognition of this new vision will then reinforce the European component and build a positive feedback loop for the further implementation of DE across the globe.     

Towards integrated essential variables for sustainability

ABSTRACT

Measuring the achievement of a sustainable development requires the integration of various data sets and disciplines describing bio-physical and socio-economic conditions. These data allow characterizing any location on Earth, assessing the status of the environment at various scales (e.g. national, regional, global), understanding interactions between different systems (e.g. atmosphere, hydrosphere, biosphere, geosphere), and modeling future changes. The Group on Earth Observations (GEO) was established in 2005 in response to the need for coordinated, comprehensive, and sustained observations related to the state of the Earth. GEO’s global engagement priorities include supporting the UN 2030 Agenda for Sustainable Development, the Paris Agreement on Climate, and the Sendai Framework for Disaster Risk Reduction. A proposition is made for generalizing and integrating the concept of EVs across the Societal Benefit Areas of GEO and across the border between Socio-Economic and Earth systems EVs. The contributions of the European Union projects ConnectinGEO and GEOEssential in the evaluation of existing EV classes are introduced. Finally, the main aim of the 10 papers of the special issue is shortly presented and mapped according to the proposed typology of SBA-related EV classes.     

THE COLOURS QUESTION

Abstract

The foundation of my former paper was nothing more substantial than a recollection of reading or hearing long ago that the property of the four colours existed in practice but had never yielded to strict theoretical analysis. I am therefore most grateful to Col. G. S. C. Cooke and Mr. G. W. Ross Jackson for their letters to the Editor (vol. iii, no. 15, pp. 52–5) citing the relative authorities, as they enable me to locate and acknowledge my debt to Mr. W. W. Rouse Ball, whose book was certainly in my hands in the Oxford Union Library some forty years ago. I wish I could remember his demonstration of the problem, but my subconscious faculties seem, from what Col. Cooke says, to have evolved a tolerable imitation of it, and until I have an opportunity of seeing the book again or of consulting any of the other authorities, I shall rest content in the assurance that, wherever my arguments may differ in substance from those of Mr. Rouse Ball, my errors will be so flagrant as to deceive none but myself, though my serenity in this connexion is somewhat shaken by the fate that seems to have attended the first welcome efforts to unmask a few of them.     

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.     

Fuzzy Modelling of African Ecoregions and Ecotones Using AVHRR NDVI Temporal Imagery

Abstract

Conventional methods of deriving global or continental vegetation maps from the National Oceanic and Atmospheric Administration's (NOAA) Advanced Very High Resolution Radiometer (AVHRR) time series data are based on two‐value Boolean logic, which cannot properly model the so‐called ecotone, the transition zone between adjacent ecosystems. New methods and data models that have been developed on the basis of fuzzy logic to address the “mixed pixel” issue in multi‐spectral imagery can also be used with multi‐temporal imagery to handle the mixture of vegetation types within an ecotone. This study introduces the concept of semantic space and its transformation from spectral feature space, which utilizes a fuzzy logic approach to characterize the continuum of vegetation communities in the African continent from AVHRR multi‐temporal (12 months for three years from 1986 to 1988) NDVI data. The fuzzy procedure was based on the Fuzzy c‐Means (FCM) algorithm with significant modifications to improve processing speed for handling large volumes of data. A second‐order mapping approach was also devised to explicitly represent subdominant vegetative coverage in ecotones and other heterogeneous regions. Comparisons between a Sub‐Saharan African Vegetation Map compiled by the International Union for Conservation of Nature (IUCN) in 1986 and the maps derived from this study demonstrated that fuzzy modeling and classification might provide a better and more realistic representation of the vegetative characteristics of the region.     

The use of atmospheric dispersion in optical distance measurement

The development of lasers, new electro-optic light modulation methods, and improved electronic techniques have made possible significant improvements in the range and accuracy of optical distance measurements, thus providing not only improved geodetic tools but also useful techniques for the study of other geophysical, meteorological, and astronomical problems. One of the main limitations, at present, to the accuracy of geodetic measurements is the uncertainty in the average propagation velocity of the radiation due to inhomogeneity of the atmosphere. Accuracies of a few parts in ten million or even better now appear feasible, however, through the use of the dispersion method, in which simultaneous measurements of optical path length at two widely separated wavelengths are used to determine the average refractive index over the path and hence the true geodetic distance. The design of a new instrument based on this method, which utilizes wavelengths of6328 ? and3681 ? and3 GHz polarization modulation of the light, is summarized. Preliminary measurements over a5.3 km path with this instrument have demonstrated a sensitivity of3×10 ⁻⁹ in detecting changes in optical path length for either wavelength using1-second averaging, and a standard deviation of3×10 ⁻⁷ in corrected length. The principal remaining sources of error are summarized, as is progress in other laboratories using the dispersion method or other approaches to the problem of refractivity correction.     

On the multivariate total least-squares approach to empirical coordinate transformations. Three algorithms

The multivariate total least-squares (MTLS) approach aims at estimating a matrix of parameters, Ξ, from a linear model (Y−E _Y = (X−E _X ) · Ξ) that includes an observation matrix, Y, another observation matrix, X, and matrices of randomly distributed errors, E _Y and E _X . Two special cases of the MTLS approach include the standard multivariate least-squares approach where only the observation matrix, Y, is perturbed by random errors and, on the other hand, the data least-squares approach where only the coefficient matrix X is affected by random errors. In a previous contribution, the authors derived an iterative algorithm to solve the MTLS problem by using the nonlinear Euler–Lagrange conditions. In this contribution, new lemmas are developed to analyze the iterative algorithm, modify it, and compare it with a new ‘closed form’ solution that is based on the singular-value decomposition. For an application, the total least-squares approach is used to estimate the affine transformation parameters that convert cadastral data from the old to the new Israeli datum. Technical aspects of this approach, such as scaling the data and fixing the columns in the coefficient matrix are investigated. This case study illuminates the issue of “symmetry” in the treatment of two sets of coordinates for identical point fields, a topic that had already been emphasized by Teunissen (1989, Festschrift to Torben Krarup, Geodetic Institute Bull no. 58, Copenhagen, Denmark, pp 335–342). The differences between the standard least-squares and the TLS approach are analyzed in terms of the estimated variance component and a first-order approximation of the dispersion matrix of the estimated parameters.     

BOWDITCH TRAVERSE ADJUSTMENT AND A MODIFICATION: NOTES

Abstract

In the second part of the paper on this subject in the last issue (30, 483) the references to the relative angular and linear closures are rather misleading. Mr Clendinning points out that the probable angular error at a station must be considered; the mean error is clearly different.     

THE DOMINION LAND SURVEYOR: SOME HISTORICAL FACTS,HIS TRAINING AND QUALIFICATIONS

Abstract

The Dominion of Canada, with an area approximating that of Europe, is the largest and most populous of the great self-governing Dominions of the British Empire. Through the British North America Act, 1st July 1867, the Union of Upper and Lower Canada, with Nova Scotia and New Brunswick, were united to form the Dominion, Upper and Lower Canada being designated as the provinces of Ontario and Quebec. An expansion was made possible on 19th November 1869 by the Deed of Surrender to the Crown of the Hudson's Bay Company's territorial, rights in the Northwest. On 12th May 1870 the Province of Manitoba was established, and on 15th July the Northwest Territories were transferred to the Dominion, and Manitoba was admitted into Confederation. Although the boundaries of Manitoba have since been enlarged and those of the Northwest Territories diminished through the creation in 1905 of the Provinces of Saskatchewan and Alberta, the control of the resources and public lands in the West remained under Dominion authority until the year 1930. By this brief statement we are enabled to understand the background of what has developed into the largest connected and systematic Public Lands Survey in any country, that of the Canadian Northwest; and this survey is unique in having been performed under one organization.     

A VLBI Delay Model for Radio Sources at a Finite Distance

A relativistic delay model for Earth-based very long baseline interferometry (VLBI) observation of sources at finite distances is derived. The model directly provides the VLBI delay in the scale of terrestrial time. The effect of the curved wave front is represented by using a pseudo source vector K = (R ₁ + R ₂)/(R ₁ + R ₂), and the variation of the baseline vector due to the difference of arrival time is taken into account up to the second-order by using Halley’s method. The precision of the new VLBI delay model is 1 ps for all radio sources above 100 km altitude from the Earth’s surface in Earth-based VLBI observation. Simple correction terms (parallax effect) are obtained, which can also adopt the consensus model (e.g. International Earth Rotation and Reference Frames Service conventions) to finite-distance radio source at R > 10 pc with the same precision. The new model may enable estimation of distance to the radio source directly with VLBI delay data.     

A new global TEC model for estimating transionospheric radio wave propagation errors

Space-based navigation and radar systems operating at single frequencies of <10 GHz require ionospheric corrections of the signal delay or range error. Because this ionospheric propagation error is proportional to the total electron content of the ionosphere along the ray path, a user friendly TEC model covering global scale and all levels of solar activity should be helpful in various applications. Since such a model is not available yet, we present an empirical model approach that allows determining global TEC very easily. Although the number of model coefficients and parameters is rather small, the model describes main ionospheric features with good quality. Presented is the empirical approach describing dependencies on local time, geographic/geomagnetic location and solar irradiance and activity. The non-linear approach needs only 12 coefficients and a few empirically fixed parameters for describing the broad spectrum of TEC variation at all levels of solar activity. The model approach is applied on high-quality global TEC data derived by the Center for Orbit Determination in Europe (CODE) at the University of Berne over more than half a solar cycle (1998–2007). The model fits to these input data with a negative bias of 0.3 TECU and a RMS deviation of 7.5 TECU. As other empirical models too, the proposed Global Neustrelitz TEC Model NTCM-GLis climatological, i.e. the model describes the average behaviour under quiet geomagnetic conditions. During severe space weather events the actual TEC data may deviate from the model values considerably by more than 100%. A preliminary comparison with independent data sets as TOPEX/Poseidon altimeter data reveals similar results for NeQuick and NTCM-GL with RMS deviations in the order of 5 and 11 TECU (1 TECU = 10¹⁶ electrons/m²) for low and high-solar activity conditions, respectively. The more extended data base of ionosphere information that accumulates in the coming years will help in further improving the set of coefficients of the model.     

Maps for Planning

Abstract

Maps play an important part in planning at national, regional and local levels. This role should increase ill the future as greater use is made of computers.

This paper was presented to the annual Symposium of the Society in September 1970, at the University of Bristol.     

An improved algorithm for supervised fuzzyC-means clustering of remotely sensed data

This paper describes an improved algorithm for fuzzyc-means clustering of remotely sensed data, by which the degree of fuzziness of the resultant classification is decreased as comparing with that by a conventional algorithm: that is, the classification accuracy is increased. This is achieved by incorporating covariance matrices at the level of individual classes rather than assuming a global one. Empirical results from a fuzzy classification of an Edinburgh suburban land cover confirmed the improved performance of the new algorithm for fuzzyc-means clustering, in particular when fuzziness is also accommodated in the assumed reference data.