Geographic Information Systems: An Introduction, 3rd Edition

10.3 Photogrammetric Mapping

Photogrammetry means “picture measurement.” The word describes a basic process first used in 1851 by A. Laussedat in France. Laussedat's original work had little practical application, because the lenses and photographic printing techniques of his time were too inaccurate for precision measurements. Toward the end of the nineteenth century, however, E. Deville, a Canadian, devised a stereoscopic machine to process photographs taken from theodolites. Subsequently, phototheodolites were developed specifically for that purpose. Phototheodolite techniques were eventually used widely, particularly for mapping the Alps of Central Europe. In 1909 the first instrument for mapmaking was built. As in so many other fields, it was military necessity that accelerated development. During World War I, balloons and airplanes were found to be excellent platforms for photography. The airplane eventually proved to be the more successful, because a single aircraft could fly along a prescribed course and take numerous overlapping photographs (Figure 10.7).

An overlapping pair of two photos forms the basis of stereoscopic viewing of the photographed terrain. Such a pair of photos can be placed in different instruments to recreate the ray path from the photography (Figure 10.8) and, thus, the three-dimensional terrain. These instruments are called stereo plotters.

Figure 10.7 ...