(b Moulins, France, 19 April 1819; d. Paris, France, 18 March 1907)
After graduating from the École Polytechnique in 1840, Laussedat joined the Engineer Corps of the French army. He spent some years working on the fortifications of Paris and along the Spanish border, then taught courses in astronomy and geodesy at the École Polytechnique. In 1856 he was made professor of geodesy, and in 1873 he became professor of geometry at the Conversatoire des Arts et Métiers. He was promoted to colonel in the Engineer Corps in 1874 and retired as an officer in 1879. Laussedat became the director of studies at the École Polytechnique in 1880, and in 1881 succeeded HervéMangon as director of the Conservatoire des Arts et Métiers. He was a member of the council of the Paris observatory, and during the siege of Paris (1870-1871) presided over the commission charged with the establishment of a department of visual communication. In 1894 he was elected a member of the Académie des Sciences.
Laussedat’s main contribution was in the field of photogrammetry. From about 1849 he carried out extensive investigations on the use of photography to prepare topographic maps. In 1858 he use a glassplate camera. supported by a string of kites, for aerial photography. He also prepared some maps from photographs taken from balloons (during a photographic trip in a balloon called L’Univers, he broke his leg). Laussedat abandoned his experiments on aerial photography with kites and balloons about 1860, primarily because it was extremely difficult to take enough photographs from one air station to cover the entire area visible from that station.
Laussedat made considerable use of ground photography by means of a phototheodolite (a combination of theodolite and camera). In 1859 he announced to the Académie des Sciences that he had successfully prepared topographic maps from the photographs taken with this instrument. His new technique was critically examined by two members of the Academy, Pierre Dausssy and P. A. Laugier, and was found to be completely satisfactory. Laussedat exhibited the first known phototheodolite at the Paris Exposition of 1867, along with a map of Paris he had prepared with it. The map compared favorably with those prepared with the aid of conventional surveying instruments.
In spite of the ridicule he received from many of his contemporaries, Laussedat conducted further research on the use of photographs to prepare topographic maps. He successfully developed a new method of mathematical analysis to convert overlapping perspective views into orthographic projections in one plane. Laussedat discussed the results of his many years of research in Recherches sur les instruments, les mèthodes et le dessin topographiques. The book was highly acclaimed, and some of the principles he laid down are still in use. Because of his manifold contributions to the field of aerial photography, he is often called the “father of photogrammetry.”
Laussedat’s writings include Expériences faites avec l’appareil à mesurer les bases appartenant à la Commission de la carte d’Espagne (Paris, 1860); Leçons sur l’art de lever les plans (Paris, 1861); Recherches sur les instruments, les méthodes et le dessin topographiques, 3 vols. (Paris, 1898-1903); and La délimitation de la frontière francoallemande (Paris, 1901). See also “Sur le progrès de l’art de lever les plans à l’aide de la photographie en Europe et en Amérique,” in Comptes rendus … des séances de l’Académie des sciences, Session of 6 Feb. 1896.
Asit K. Biswas
Margaret R. Biswas