Tendance générale au relachement de la précision dans l'utilisation de la photogrammétrie aux levés topographiques

Abstract

This article is a reply to the appeal published in Photogrammetria, 25(5/6), written by Prof. B. Hallert, in which he expressed the opinion that high-precision photogrammetry has a tendency to rest on its laurels—particularly in the field of cartography—an opinion which the present author shares. This article gives details of the precautions taken at the French National Geographical Institute (I.G.N.) of which the author is director, to obtain the maximum precision in altimetry. Results are given which appear superior to those announced in the recent I.S.P. tests. The author favours publication of the data concerning the true precision obtained in the case of largescale topographic surveys carried out by means of photogrammetry. He fears that a relapse in standards of accuracy is to be noted, largely due to the generalization of the use of film instead of plates and to the abandonment of the Porro-Koppe principle.