Aimé Laussedat

Aimé Laussedat

Aimé Laussedat (born April 15, 1819 in Moulins , † March 18, 1907 in Paris ) was a French officer and scientist.

Life

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Laussedat became professor of geodesy at the École polytechnique in Paris in 1856 and director of the Conservatoire national des arts et métiers in 1881 . He published his results in numerous reports. In 1867, the maps based on his theories were issued in Paris and later also in Chicago.

In 1894 the Académie des Sciences in Paris accepted Laussedat as a member. Laussedat Heights in Antarctica have borne his name since 1960 .

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Laussedat, together with Albrecht Meydenbauer, is considered to be one of the fathers of photogrammetry . In 1851 he published his theses in "Métrophotographie". In 1861 he was the first to use terrestrial recordings to produce topographic maps .

In 1846, as a young captain, he was working on a map of the Pyrenees in France . In order to avoid the laborious field recording and the inaccurate freehand drawing of perspectives, he used the camera lucida invented by William Hyde Wollaston and tested his new method on the facade of the Hôtel des Invalides in Paris in 1849. After this proved to be feasible In the following year, Laussedat took the first topographical record of the fortress of Vincennes in 1850. To avoid the focusing problem of the camera lucida, Laussedat changed the shape of the upper prism surface. This brought the image of the landscape into the plane of the measuring table , so that the use of the camera lucida offered a relatively powerful, accurate and fast process. With the naming of this method as Ionometrics (Greek: measurement of the image / image) Laussedat gained a place in science. For military purposes and for distance measurements of up to 15 km, he combined the camera lucida with a telescope . At the time of iconetrics , landscapes could already be mapped with photography and the camera obscura , but, in Laussedat's opinion, the camera and film material were still too heavy and unstable for field use. The angle of view of the camera obscura of 25 ° in contrast to 60 ° for the camera lucida turned out to be rather unfavorable for topographical recordings. In 1859, the optician Bertaud, in collaboration with the instrument maker Brunner, built a prototype of what would later become the phototheodolite , which Laussedat designed according to the requirements for a better instrument. It was a photographic camera with a bussole and a small dragonfly . It already had fiducial marks which were projected onto the resulting image. A binocular level for leveling , a vernier for diametrical reading of the inclination angle of the telescope and a vernier for reading the horizontal angle were already used in the so-called chambre obscure topographique . Laussedat was able to convince representatives of the French Academy to use the chambre obscure topographique in cartography in 1859 . The Ministry of War then commissioned him to complete the topographical survey of the place Buc near Versailles . This map covered approx. 200 ha and was taken in two days. In the further course a special unit of the military was set up, which in the following years took pictures of Paris, parts of the Alps , the area around Toulon , the Vosges and Alsace based on Laussedat's model. The coverage of the approx. 72,000 hectare area on a map scale of 1: 5000 proved the correctness of the theoretical principles as well as the procedure in the field.

In 1858 the photographer Gaspard-Félix Tournachon, better known under his pseudonym Nadar , made his first photographic attempts from a balloon, on which he was advised by Laussedat. Laussedat, however, was more interested in terrestrial recordings, which is why he devoted himself to improving his instruments.

Publications (selection)

• La metrophotography . Gauthier-Villars, Paris 1899.

literature

• Teodor J. Blachut: The early days of photogrammetry up to the invention of the airplane (= history of photogrammetry volume 1). Publishing house of the Institute for Applied Geodesy, Frankfurt am Main 1988, pp. 20-26.

Remarks

1. ^ List of deceased members .