ALBERT

Notes: This short note sets out a personal experience of the transition from an academic environment to the great wide world of marketing and discusses some of the similarities and differences between the two.

Notes: In order to realise the full potential of photogrammetry for national map revision, photographic acquisition lead times and, where possible, costs must be significantly reduced. In this paper a review of alternative platform and camera configurations is made and tests are undertaken utilising simulated data and medium format data taken from an existing project. The results suggest that the medium format camera and helicopter combination may have much to offer while the small format camera and microlight aircraft systems have yet to be developed into an effective data acquisition and map compilation system.

Notes: The author draws attention to the public nature of an archive compared with the privacy of a collection in the commercial sector. He emphasises the nature of copyright as it affects the products of his own company and explains some of the characteristic features of a commercial operation involved in the acquisition and supply of aerial photography.

Notes: A previous paper (Gugan, 1987) described the geometric model used to find the exterior orientation of dynamic SPOT imagery. The present paper considers the results of measurement and interpretation tests performed on a number of stereomodels. The image quality is assessed in comparison with the original digital data. Level 1A stereomodels with different base height ratios, numbers of control points and with different control point accuracies are compared. Accuracies obtained with level 1P and 1B data are also reported. The information content of the imagery is assessed by feature plotting followed by comparison with the 1:50 000 and 1:100 000 scale maps of the area. The importance of high quality photographic imagery and operator experience are noted.

Notes: Work is reported on the production of terrain elevation data from SPOT imagery. An important step in this process is determination of exterior orientation parameters for the images. Although an initial estimate is available in the SPOT header, refinements are required based on plan and height data. These are generally derived from photogrammetric measurements (or sources such as global positioning satellite systems), but accurate manual determination is time consuming.This paper reports an alternative approach by investigating the use of existing map data (located on the earth's surface and in a known projection) to find corresponding “ground control points” in both map and image. Available maps may be in digital or paper form depending on the state of development of mapping in the part of the world being studied. The last revision date and the cartographic generalisation employed will also effect the fidelity of the final result. Practical semi-automatic techniques for determining the height of ground control points from existing map data are described, including multiple profiles through digitised contour data, a commercial terrain modelling package based on Delaunay triangulation and the use of triangulation points on prominent features.Comparisons between the methods are made and results obtained are compared with Institut Géographique National datasets and photogrammetric measurements. Methods for fully automating not only the height determination but also the location of ground control features within a map database are discussed. Map and image registration is described and illustrated using Laser-Scan's Rover software. Interactive and automated methods of registration are discussed.

Notes: The Overseas Surveys Directorate (OSD) of the Ordnance Survey of Great Britain (OS) has experimented with using SPOT I HRV data for topographic line mapping at 1:100 000 scale in the Yemen Arab Republic (YAR). Results of these tests indicate that sufficient accuracy to support 1:100 000 scale mapping with a 40 m contour interval is possible but that the compilation of detail is incomplete. More emphasis on field completion and verification is required than with traditional techniques to maintain a standard 1:100 000 scale mapping specification. Costs of mapping large areas can be significantly reduced but savings are yet to be made in providing ground control. OSD has acquired expertise and hardware in a new mapping process, not to replace traditional mapping systems but to complement them under appropriate conditions. OSD has developed sufficient confidence in the use of SPOT to commit itself to mapping approximately 25 000 square kilometres of north east Yemen Arab Republic.

Notes: Bundle triangulation is an efficient tool for spatial point determination in architectural photogrammetry. All the information available in image and object space may be introduced in a combined adjustment yielding high precision and reliability. Camera calibration performed simultaneously with the object restitution process enables the application of convenient and flexible imaging systems based on professional photographic technology. Thus the survey of monuments can be carried out rapidly with a minimum of personnel and equipment. The photogrammetric recording of the basilica of San Francesco in Siena is presented as an example of the application of this survey procedure. The field work was accomplished in a few days. The equipment used consisted of a partial metric camera, an engineering theodolite and a tape. The bundle adjustment results gave spatial object co-ordinates with a r.m.s.e. of ± 15 mm for a point.

Notes: Book review in this aticle:INTRODUCTION TO THE PHYSICS AND TECHNIQUES OF REMOTE SENSING. By C. Elachi.COMPUTER PROCESSING OF REMOTELY-SENSED IMAGES. By P. M. Mather.ARCTIC AIRMEN. B E. Schofield and R. C. Nesbit.WARBURTON'S WAR. The life of Wing Commander Adrian Warburton, DSO and Bar, DFC and Two Bars, DFC (USA). By T. Spooner.MAP PROJECTIONS—A WORKING MANUAL. By. J. P. Snyder.WORLD MAPPING TODAY. By R. B. Parry and C. R. Perkins.CONTROL SURVEYS IN CIVIL ENGINEERING. By M. A. R. Cooper.INTRODUCTION TO REMOTE SENSING. By J. B. Campbell.ANALYTICAL PHOTOGRAMMETRY. By S. K. Ghosh.

Notes: The availability of data in digital formats, the rapid evolution of computer systems and the increased demands for cartographic databases are causing photogrammetrists to consider ways of integrating photogrammetric, remote sensing and database technologies. Examples are presented involving the use of aerial photographs and satellite images in combination with geographical information systems and image processing techniques to assess soil erosion, growth of aquatic vegetation and to enhance satellite images for the compilation or revision of map products.

Notes: Following the installation of the Wildmap digital mapping system, B.K.S. Surveys Ltd. has successfully completed a number of digital mapping projects in Europe, the Middle East and the United States. As a result of experience gained through meeting clients’requirements, carrying out market research and making in house developments the company has updated its original conceptual approach to digital mapping to meet current demands for a land information system. At present B.K.S. is involved in creating a database that is composed of utility, cadastral and topographical data designed for both graphical output and digital processing for resource planning.

Notes: The development and operation of a remote control system for a camera rig and for the camera attached to it are described. Now there is the possibility of reducing the crew from three to two for many tasks and to use the extra payload to collect contemporaneous data using a second airborne system.

Notes: In spite of the striking progress in block adjustment techniques, it is widely assumed that their application continues to be out of reach for a large part of the photogrammetric community that cannot afford expensive computer systems. The COBLO program performs rigorous block adjustment with models and can be implemented even on inexpensive microcomputers. The first COBLO versions are in operation in several places in South America and Europe and the latest versions, which are considerably more efficient, are now being introduced. This paper describes the main features of different COBLO versions and presents the experience of some users.

Notes: In this paper, the author discusses some of his experiences of the past 20 years as a lecturer in photogrammetry and surveying. Comment is made upon the relationship between training and education but with some greater emphasis on the educational topic, and on the role of the lecturer. The final section discusses those elements of a course in photogrammetry which have a strong educational content.

Notes: This paper describes briefly the survey and photogrammetric work carried out for the detailed recording of the Minoan Palace of Cnossos, a project undertaken by a group of three private survey firms (N. Perdikaris, Dimopoulos and Associates and Stambouloglou and Associates) for the Archaeological Service of the Hellenic Ministry of Culture and Science.

Notes: Analytical plumbline and serf calibration techniques are applied to the calibration of two underwater cameras: a Rolleifex SLX réseau camera with an Aquamarin WKD-SLX/6006 submarine housing and a Nikonos V underwater camera. The Rolleiflex was fitted with a 50 mm Distagon f/4 lens and the Nikonos with a 28 mm Nikkor-UW f/3.5 lens. Comparisons of the results from the two methods of camera calibration are described. Theoretical differences are predicted for in-air versus in-water values for radial distortion. When these are compared to the actually observed values of distortion, an insight is provided of the precisions claimed for each method of camera calibration.

Notes: A new lightweight vertical camera rig which can be clamped to the front legs of the front seat of a light aircraft is described. In one version, a fixed transparent fairing is attached to the door, whereas in the second version the fairing is attached to the camera rig itself which can then be extended and retracted in flight. This rig has received C.A.A. (Civil Aviation Authority) Approval.

Notes: SPOT-1, launched on 22nd February, 1986, has provided the first opportunity to produce topographic maps from space on an operational basis. The use of SPOT imagery can be justified because of reduced costs and reduced lead times for map production. However SPOT imagery cannot be handled in the same way as conventional photography and it requires new procedures to be adopted, The two main reasons for this are the large area covered by each image and the dynamic form of sensing. The procedures discussed in this paper have been implemented in a working system for map compilation.

Notes: Three authors, representing commercial, educational and governmental photogrammetric organisations, report on their initial uses of analytical plotters.

Notes: Book reviews in this article:PROCEEDINGS OF THE INTERNATIONAL SYMPOSIUM ON SPACE TECHNIQUES FOR GEODYNAMICS. Edited by J. Somogyi. Hungarian Academy of Sciences. Sopron. Hungary.THE SURVEILLANT SCIENCE: REMOTE SENSING OF THE ENVIRONMENT. Edited by R. K. Holz. Second edition. John Wiley and Sons Ltd., New York and Chichester.DISCOVERY FROM THE AIR. By G. W. G. Allen. Edited by J. S. P. Bradford and O. G. S. Crawford with Introduction and Captions by D. N. Riley. Aerial Archaeology.PRINCIPLES OF REMOTE SENSING. By P. J. Curran. Longman, London and New York.SATELLITE OCEANOGRAPHY. By I. S. Robinson. Ellis Horwood Ltd, Chichester.THE RIGHT OF THE LINE. The Royal Air Force in the European War 1939–1945. By J. Terraine. Hodder & Stoughton, London.INDUSTRIAL HISTORY FROM THE AIR. By K. Hudson. Cambridge University Press, Cambridge.INTRODUCTION TO SATELLITE OCEANOGRAPHY. By G. A. Maul. Martinus Nijhoff, Dordrecht.REMOTE SENSING IN CIVIL ENGINEERING. Edited by T. J. M. Kennie and M. C. Matthews. Blackie and Son Ltd. Surrey University Press, Glasgow and London.

Notes: The use of small computers for on line data processing in photogrammetry has developed from the desktop calculators of the early 1970s to the microcomputers of today. The restrictions of machine code programming, small memory and limited display have been overcome. Software has been written for the PI-1A monocomparator using the BBC microcomputer for a calibration test, relative orientation, and strip formation and adjustment in the on line mode. This low cost system is suitable for training inexperienced operators or students in analytical photogrammetry, with the sequence of observation guided by operator prompts and with error checking computations displayed. Re-observations can be made on line and acceptable observations stored for input to the strip adjustment program or subsequent block adjustment.

Notes: Using modern techniques, the analysis of amateur photographs yields results with almost the same accuracy level as with metric photographs. This paper gives a classification of data processing techniques for amateur photographs and presents a well proven method for the treatment of existing amateur photographs, known as Metric Photo Perspective Transformation (MPPT). Data processing is particularly convenient and efficient if on line techniques are used. Operational procedures for the treatment of additional parameters and for the detection of blunders in a time critical on line triangulation system are proposed.

Notes: The paper presents research and development at the Thematic Information Service of the Natural Environment Research Council (NERC) on the topic of integrated geographic information systems. The term integrated is used to describe the incorporation of vector digitised map data and raster scanned remotely sensed data within a single computational environment and with a single interface to the user. Point sampled and statistical data can also be handled by the system. The general structure and working of the Thematic Information Service (TIS) is described only to the extent that it is relevant to providing the background to the research or to highlighting why the specific approach described has been taken.

Notes: A procedure for digital image correlation is described which is based on least squares window matching. The immediate aim is high precision parallax assessment, point transfer, and point measurement. Experiments and theory have confirmed the high accuracy potential of the method. By implementation of charge coupled device (CCD) video cameras in an analytical plotter, an experimental hardware and software configuration has been established with which the operational on line application of digital image correlation for conventional photogrammetric measuring tasks can be tested. First results of calibration and performance of the system are presented. They allow optimistic conclusions as to the further development and practical application of digital image processing in photogrammetry.

Notes: Book review in this aticle:DESERTS AND ARID LANDS. Edited by F. El-Baz.IMAGES OF THE WORLD AN ATLAS OF SATELLITE IMAGERY AND MAPS. By C. Mueller-Wille with an interpretive supplement by R. M. Smith.ELEMENTS OF PHOTOGRAMMETRY. By P. R. Wolf.

Notes: The essential features of equipment for mobile processing are outlined with reference to the development of small photographic laboratory vehicles for use in the Jield. The resulting air film processor, the Wainco Products Limited 392. is described and details are given of trials carried out to establish its performance for a range of tasks in both reconnaissance and survey. The tests cover the sensitometric and drying behaviour of several air films in current use and include an analysis of the dimensional stability o f j l m in the processor. Applications using direrent containers and eflectiveness in improvised situations are also described and possible future variants of the processor are suggested.

Notes: This paper is concerned with a new technique (the terrestrial/photogrammetric (TP) technique) for the detection and compensation of systematic height errors in block aerial triangulation. The technique improves the height accuracy of such triangulation by reducing the original bridging distance, using new bands of corrected photogrammetric tie points as height control together with the original bands of the terrestrial (or ground) height control. A number of photogrammetric blocks with different characteristics and configurations have been tested in a comprehensive manner. The tests show that the TP technique gives consistent results over a wide range of circumstances and that it is a most effective, simple and inexpensive method for the compensation of systematic errors.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméCet article relate une technique nouvelle permettant de détecter et de compenser les erreurs altimétriques systématiques dans l'aérotriangulation par blocs: la technique terrestre/photogrammétrique (TP). Cette technique améliore la précision altimétrique de l'aérotriangulation en réduisant la distance de l'aérocheminement original, grâce à l'utilisation d'un canevas de points d'appuis altimétriques composés de points de liaison photogrammétriques corrigés, en supplément du canevas original de points d'appui altimétriques déterminés sur le terrain.On a essayé de manière approfondie un grand nombre de blocs dotés de caractéristiques et de configurations diverses. Les essais montrent que la technique TP fournit des résultats fiables dans un large éventail de circonstances et que c'est une méthode de compensation des erreurs systématiques efficace, simple et peu coûteuse.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungIm Artikel wird ein neues Verfahren behandelt (das terrestrisch-photogrammetrische Verfahren (TP)), das zur Aufdeckung und Kompensation system-atischer Höhenfehler in der Block triangulation dient. Es wird die Höhengenauigkeit durch Verkürzung der ursprünglichen Überbrückungsdistanz verbessert, indem neue Streifen korrigierter Verbindungspunkte als Höhenpasspunkte zusammen mit den ursprünglichen Reihen der terrestrischen Höhenpasspunkte verwendet werden. Eine Anzahl photogrammetrischer Blöcke unterschiedlicher Figur und Charakteristik wurde umfassend getestet. Die Tests zeigen, dass die TP-Methode konstante Ergebnisse für einen grossen Bereich van Möglichkeiten ergibt und dass es ein höchst effektives, einfaches und billiges Verfahren zur Eliminierung systematischer Fehler ist.

Notes: The development of an automated photographic measuring system (APM) is described. A very accurate laser beam scanning microdensitometer is used to digitise the photographic plate and a series of on line computers analyses the data during scanning. The system is available as a national facility for United Kingdom astronomers and guest investigators.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn décrit un systéme automatisé de saisie de données sur cliché. Un microdensitométre à laser numérise la plaque photographique et les données sont analysées en temps réel par ordinateur. Le systeme est destiné aux astronomes du Royaume Uni et aux chercheurs y séjournant.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungBeschreibung eines automatisierten photographischen Messsystems (APM). Ein hochgenaues Laser-Mikrodensitometer wird dabei zur Digitalisierung der Bilder benutzt, undeine Serie von On-line-Rechnern analysiert die Daten während der Abtastung. Das System steht für Astronomen im Vereinigten Königreich und anderen Forschern zur Verfügung.

Notes: During June and July 1981, synthetic aperture radar imagery was acquired of selected sites in ten European countries as part of the European SAR 580 campaign. Evaluation of this imagery in the UK will be carried out by 18 approved experiments (out of 56 for Europe) when the processed data becomes available to investigators. To assist the evaluation process, a review is given of some recent research on applications of imaging radar in agricultural and urban areas. Research is described which considered the effects of terrain parameters and radar parameters on crop classification accuracy. The relative merits of a quantitative or a qualitative approach in classification of radar data are considered. Combined use of radar and Landsat data achieves a marked improvement in classification accuracy. The development of spatial filtering techniques may assist in the problem in urban areas resulting from the dependence of image tone on the relative alignment of ground features and radar look direction.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméPendant les mois dejuin et juillet 1981, on a, dans le cadre de la campagne européenne SAR 580, recueilli des données de radar imageur à synthèse d'ouverture sur des sites choisis dans une dizaine de pays d'Europe. Ces données seront évaluées au Royaume-Uni au moyen de 18 expériences ayant été acceptées (sur un total de 56 menées en Europe); ce travail commencera dès que les données une fois traitées seront distribuées aux chercheurs. Pour accompagner cette procédure d'evaluation, on fournit une analyse de quelques recherches récentes sur les applications de l'imagerie radar aux zones agricoles et urbaines.L'une de ces recherches prenait en compte les effets des paramètres liés au terrain sur l'exactitude de la classification des cultures. Les mérites réciproques des approches quantitatives et qualitatives dans la classification des données radar sont également examinés.Le recours à une combinaison de données radar et Landsat permet d'améliorer de manière significative l'exactitude de la classification. La mise en oeuvre des techniques de filtrage spatial peut aider à réduire, dans les zones urbaines, les conséquences néfastes sur la tonalité de l'image, d'objets au sol en alignement relatif avec la direction d'observation du radar.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungIm Juni und Juli 1981 erfolgten Radaraufnahmen mittels synthetischer Apertur von ausgewählten Gebieten in 10 europäischen Ländern als Teil der Europäischen SAR 580 Kampagne. Die Analyse dieser Aufzeichnungen wird im Vereinigten Königreich durch 18 (aus insgesamt 56 für Europa) bestätigte Experimente erfolgen, nachdem die Daten zur Verfügung stehen. Um den Analysenprozess zu unterstützen, wird ein Überblick über kürzliche Forschungen zu Radaraufzeichnungen in landwirtschaftlichen und städtischen Gebieten gegeben. Es werden auch Forschungen beschrieben, bei denen die Einflüsse von Geländeparametern auf die Genauigkeit der Ernteklassifizierung untersucht wurden. Der relative Wert eines quantitativen oder qualitativen Versuchs zur Klassifizierung von Radardaten wird abgeschätzt. Eine Kombination von Radarund Landsat-Daten ergibt eine merkliche Verbesserung bei Klassifizierungsgenauigkeit. Die Entwicklung von Verfahren der räumlichen Filterung kann von Wert bei städtischen Gebieten sein, weil es eine Abhängigkeit des Grauwertes von der relativen Ausdehnung von Geländecharakteristika und der Richtung der Radaraufnahme gibt.

Notes: Some aspects of the XYZBLC suite of programs for aerial triangulation are described. The Ordnance Survey Bute block of photography at a scale of 1: 24000 is computed by independent models using XYZBLC. Three of the strips in the block are treated as a test block and are computed with different configurations of control. Conclusions are drawn with regard to the usefulness of height control doublets and other dense control configurations.〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Quelques aspects de l'ensemble XYZBLC de logiciels d'aérotriangulation sont décrits. Le bloc Bute de l'Ordnance Survey, composé de photographies à l'échelle du 1: 24000, a été calculé par modèles indépendants avec les logiciels XYZBLC. On a considéré trois des bandes du bloc comme formant un bloc d'essai et on les a calculées avec diverses combinaisons de canevas de points d'appui. On en tire des conclusions quant à l'utilité des doublets de points d'appui altimétriques et de diverses autres configurations denses de canevas d'appui. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Beschreibung einiger Aspekte des XYZBLC-Programmsystems zur Aero-triangulation. Ein Block des Ordnance Survey im Bildmassstab 1: 24000 wurde damit nach der Methode der unabhängigen Modelle berechnet. Drei der Streifen des Blocks wurden als Testblock behandelt und mit verschiedenen Passpunktanordnungen berechnet. Es werden Schlussfolgerungen in bezug auf die Nützlichkeit von Zwillingspunkten zur Höhenorientierung und andere dichte Passpunktanordnungen gezogen.

Notes: The wide availability of reconnaissance frame photography, together with the advantage of high image resolution that such photography provides and the extreme flight conditions under which it can be taken, means that it is of great interest to photogrammetrists. However, the geometry of the image is invariably distorted due to the mode of operation of the camera. In this paper, the effects of the focal plane shutter and apparent image motion compensation on the geometry of the photographs are considered.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméLe fait que la photographic de reconnaissance soil très répandue, conjointe-ment aux avantages que présente la grande résolution des images fournies par ces systèmes et les conditions extrêmes de vol dans lesquelles on peut les prendre, milite pour une prise en compte de lew intérêt par les photogrammètres. Toutefois la géométrie de ces images est systématiquement déformée par suite du mode de fonctionnement de la chambre. On traite dans cet article des effets de l'obturateur focal et de la compensation du filé de l'image sur la géométrie des photographies.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungDie grosse Verbreitung von Erkundungsfotos zusammen mit der grossen Auflösung solcher Fotos und den extremen Bedingungen unter denen sie auf-genommen wurden, lassen diese auch für den Photogrammeter interessant erscheinen. Die Geometrie dieser Bilder ist jedoch infolge der speziellen Kamera-funktion verzerrt. Im Artikel werden die Einflüsse des Schlitzverschlusses und des Bildwanderungsausgleichs auf die Bildgeometrie untersucht.

Notes: Book Reviewed in this article:AERIAL PHOTOGRAPHY. By G. S. Kumar.MANUAL OF PHOTOGRAMMETRY (Fourth Edition). Editor-in-Chief: C. C. Slama.

Notes: Two complementary measuring instruments are described which use a very simple principle and which take three dimensional measurements or plots directly from small objects. The first instrument can achieve accuracies of ± 0·3 mm on objects whose largest dimension is 300 mm. The second can achieve ± 0·02 mm on objects smaller than a 25 mm cube.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn présente deux instruments de mesure complémentaires el de principe très simple permettant de relever dans l'espace des coordonnées sur de petits objets, le premier avec une exactitude de ± 0.3 mm sur des objets de dimension inférieure à 300 mm, le second avec une exactitude de ± 0.02 mm sur des objets de dimension inférieure à 25 mm.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungBeschreibung von zwei Zusatzmessgeräten, die auf einem sehr einfachen Prinzip beruhen und mit denen dreidimensionale Messungen oder Auswertungen von kleinen Objekten direkt durchgeführt werden konnen. Mil dem ersten Gerät kann eine Genauigkeit von ± 0,3 mm bei maximalen Objekt abmessungen von 300 mm und mit dem zweiten von ± 0,02 mm bein Objekten, die kleiner als ein 25 mm-Kubus sind, erreicht werden.

Notes: This paper outlines the technical procedures used in commercial orthophotomap production and attempts to identify some of the main differences in technical approach between orthophotomapping and conventional line mapping.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn décrit les techniques industrielles de production d'orthophotocartes et on compare leur emploi avec celui des techniques classiques.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungSkizzierung der Technologien, die bei der kommerziellen Herstellung von Orthofotokarten angewendet werden, wobei versucht wird, die hauptsächlichen Unterschiede der Techniken zur Herstellung von Orthofotokarten und konventionellen Strichkarten aufzudecken.

Notes: This paper investigates the effect of the deviation of measured points from the standard locations when carrying out a relative orientation of a stereomodel. The analytical solution of more than 100 cases was considered and, for each case, the weights for the elements of relative orientation and the correlation coefficients were evaluated. The stability of the solution was studied by calculating the characteristic roots of the matrix of normal equations.It is shown that, theoretically, the solution of the relative orientation problem can always be achieved whenever the locations of the measured points satisfy stated geometrical requirements. However, the reliability of the solution depends on their exact positions in the stereomodel. When the accuracy is too low, in practice there is no solution.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn étudié l'effet sur l'orientation relative d'un couple de variations de position des points de base. Plus de 100 cas ont été considérés et à chaque fois ont été estimées les précisions des paramètres calculés ainsi que leur correlation. On a de plus, étudié la stabilité de la solution par l'intermédiaire des valeurs propres de la matrice normale.Il n'est pas indispensable, en principe, d'imposer de contraintes précises au choix des points de base; mais de ce choix dépend la fiabilité de la solution, faible s‘il est par trop fantaisiste.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungIn der Arbeit wird der Einfluss der Abweichung der gemessenen Punkte von ihrer Standardlage bei relativer Orientierung eines Stereomodells untersucht. Dazu werden mehr als 100 analytische Lösungen analysiert und für jeden Fall die Gewichte der Elemente der relativen Orientierung und die Korrelationskoeffizienten berechnet. Die Stabilität der Lösung wurde durch Berechnung der charakteristischen Wurzeln der Matrix der Normalgleichungen abgeschätzt.Es wird gezeigt, dass theoretisch immer die Lösung des Problems der relativen Orientierung erreicht werden kann, sobald die Lage der Messpunkte die geometrischen Anforderungen erfüllt. Die Zuverlässigkeit der Lösung hängt jedoch von der exakten Lage der Punkte ab. Wenn ihre Genauigkeit zu gering ist, gibt es praktisch keine Lösung.

Notes: A review of some recent activities undertaken by the Institut Géographique National, France (IGN) in photogrammetry is given in this paper, especially with regard to digital and space data processing, assessment of SPOT images and the development of new instruments and experimental map products. The main topics considered can be divided into three groups: aerial surveying, digital photogrammetry and space photogrammetry (including the possibility of further planetary missions).

Notes: The paper describes the material generated in carrying out architectural photogrammetric surveys. The importance of the archival nature of this material is highlighted and reference is made to the indexing and storing of the records.

Notes: Methods of creating digital terrain and landscape models for regional and site specific visualisations are described. A number of alternative approaches are discussed and their relative accuracies are considered. This is followed by a review of the computer graphics procedures which can be used to render such models. Particular attention is directed towards methods for depth cueing, hidden surface removal, shading and texturing. The effects of the atmosphere and methods of producing shadows are also examined. The paper then presents varied applications of such visualisations, including small scale, regional examples and large scale, site specific applications. In conclusion, the role of photogrammetry in the process of visualisation is assessed and possible future developments in this field are identified.

Notes: A number of published steromatching algorithms have been implemented and tested on SPOT images of areas for which gridded digital elevation models (DEMs) are available with spacings of 80 m or less, as well as ground control checkpoints.Results are presented for comparison of stereomatched output with the DEMs as well as an analysis of the errors arising and their causes. Results are discussed for planimetrically geocoded and epipolar resampled data. An error budget describing effects due to orientation, feature localisation and matching are discussed and conclusions drawn for future work in this area.

Notes: Military systems are becoming far more demanding in their requirement for geographical information. Military Survey must be able to support these requirements and consequently undertake a continuous evaluation of new potential sources and exploitation systems. In considering SPOT data, both the improved spatial resolution and the three dimensional capability afforded by the system must be investigated. Military Survey, together with universities and industry, is conducting trials on the accuracy and detail obtainable from both film and digital data. This paper will consider the three dimensional geometric fidelity of SPOT data using three different systems. The first exploits the data as a stereopair of diapositives using an analytical plotter. The second is a hybrid system in that the stereoscopic digital data are loaded into an image processing workstation which projects a stereo-image onto a split screen. This is then treated as “hardcopy” and is interactively exploited by a conventional stereoscope. The third system is completely digital in that height extraction is undertaken within a digital environment incorporating autocorrelation routines. Overall system errors of 10 m to 12 m (σ) were recorded for each exploitation system. Digital elevation model accuracies varied depending upon terrain type and image contrast.

Notes: The author has been involved in aerial triangulation, in various capacities, for some 27 years. This period has seen some very significant changes worthy of remark. This essay is a general review of that period; it does not go into detail and no formulae are quoted. The idea has been to look at the more notable developments, skipping the earlier and well documented period in favour of more recent times, particularly as regards the references. The objective will have been achieved if it provides a starting point, indicating further reading, for those who wish to study the subject in greater depth.

Notes: This paper was prepared as supporting documentation for a tutorial given by the authors under Photogrammetric Society auspices. The authors do not make any claims of novelty or innovation but they feel that the information contained in the paper will provide useful study material, especially for practitioners of photogrammetry and surveying. The following topics are covered: functional and stochastic models; the least squares process; statistical testing; optimal design methods; and numerical examples in the design of a horizontal control network and of a close range photogrammetric survey.

Notes: In 1904, Dr. H. G. Fourcade compiled the first recorded topographic map made using analytical stereophotogrammetric methods. This paper describes how, in 1985, the stereophotography was repeated in very close proximity to Fourcade's original camera base using a modern metric camera. A new topographic map was compiled by computer graphics from stereoscopic observations made on a modern stereocomparator. A direct comparison of the two sets of interpolated contour lines demonstrates that Fourcade produced a highly accurate map covering part of Devil's Peak which is adjacent to Table Mountain near the city of Cape Town.

Notes: The effect on accuracy resulting from some changes to the conventional least squares matching method is investigated. Parallaxes computed automatically with matching methods have been compared with manual measurements made in a stereocomparator. Examples have been taken from both large and small scale aerial photographs and from close range images. Different linear geometric and radiometric parameters have been used as additional unknowns. The use of data snooping in digital matching with the least squares matching method has also been investigated. The results show that the introduction of additional affine parameters has a positive effect on the accuracy when the window size is larger than 30 × 30 pixels. The use of the data snooping technique is promising. The best precision obtained was between 10 pm and 15 μm, expressed as radial root mean square deviation, corresponding to approximately half a pixel. Gross error detection is possible to a large extent with photographs of good image quality.

Notes: The author continues the discussion of a Norwegian project to develop a stereoscopic instrument which will reduce the cost of analytical photogrammetry. Parts I and II of the project were presented at the 1984 Thompson Symposium; the objective at that stage was to build an image space plotter. This paper covers Part III of the project and the extended objective to develop an inexpensive analytical plotter which links with a modern microcomputer.

Notes: Previous assessments of the accuracy of parallax bar heighting were handicapped by small sample sizes. Numerical simulation was avoided due to the difficulty of obtaining co-ordinates for the conjugate principal points. This problem has been overcome, however, and all required photograph coordinates have been rigorously computed following the generation of fictitious data for ground points and exposure stations. The parallax bar heighting process has additionally been simulated in order to investigate both external factors, such as image errors, tilts and ground relief, and also influences intrinsic in the heighting process, for example estimation of flying height, baselining, control configuration and error surface model.

Notes: During 1985, the opportunity arose to make some test flights with the Wild RC10A and the Zeiss (Oberkochen) RMK A 15/23 with forward motion compensation. This paper outlines the changes incorporated in modern cameras, summarises the Ordnance Survey's photogrammetric tasks, describes the test flights which were achieved and illustrates the results obtained.

Notes: Book reviewed in this aticle:AERIAL PHOTO-INTERPRETATION IN TERRAIN ANALYSIS AND GEOMORPHOLOGIC MAPPING. By R. A. van Zuidam.REMOTE SENSING: METHODS AND APPLICATIONS. By R. M. Hord.FRENCH-ENGLISH GLOSSARY ON SPOT, REMOTE SENSING AND THEIR APPLICATIONS. By S. T. Dyson.REMOTE SENSING. PRINCIPLES AND INTERPRETATION. Second Edition. By F. F. Sabins.APPLIED REMOTE SENSING. By C. P. Lo.HISTORY OF CARTOGRAPHY. By L. Bagrow.REMOTE SENSING YEARBOOK 1987. Edited b A. P. Cracknell and L. W. B. Hayes.WINGS OVER ICE. By P. G. Mott.MANUAL OF AERIAL PHOTOGRAPHY. By R. W. Graham and R. E. Read.

Notes: 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.