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The resection solution is aile method of determining the co-ordinates of a point which is occupied to observe directions to at least three control points. The relalil'e position of the resected point and the three control points plays the major role in deciding the accuracy of the resected point. In this paper, a detailed study of the relation between the relative positions of the resected and control points and the accuracy oj'the resected point is presented and the best relative positions are determined. IntroductionThe position fixing of points in a network developed to provide accurate control for subsidiary surveys can be obtained using different methods; for example. traversing. triangulation. trilateration, satellite positioning. intersection and resection.Of these methods, resection is the most convenient method for determining the position of an unknown point by occupying the point and measuring direclions to at least three known control points. Numerous analytical techniques have been developed for the solution of the resection problem [1][2][3][4].Nevertheless. the accuracy of the resection solution has not been treated to the knowledge of the author. What is generally known is that the resected point should not lie on the circle passing through the three given control points. This is called the danger circle; that is because an infinite number of points would form the same angles subtended by the directions from the occupied point to the observed control points and the result is an indeterminate solution.It is only the work done by Mitchell and Mitchell IS] who have criticised previous work on resection solution not dealing with the accuracy of the solution. which has raised the point that the geometry of the problem should be considered. They have stated

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. Résumé Le 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. Zusammenfassung Die 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.

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