photogrammetry

technique that uses photographs for mapmaking and surveying. As early as 1851 the French inventor Aime Laussedat perceived the possibilities of the application of the newly invented camera to mapping, but it was not until 50 years later that the technique was successfully employed. In the decade before World War I, terrestrial photogrammetry, as it came to be known later, was widely used; during the war the much more effective technique of aerial photogrammetry was introduced. Although aerial photogrammetry was used primarily for military purposes until the end of World War II, thereafter peacetime uses expanded enormously. Photography is today the principal method of making maps, especially of inaccessible areas, and is also heavily used in ecological studies and in forestry, among other uses.

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