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a map in which a locale is depicted by a combination of an aerial photograph and lines and standard symbols. In comparison with other maps, photomaps are characterized by great detail and realism; they are the best maps for orientation on terrain. The first photomaps were made in the USSR and other countries in the 1940’s, but such maps came into widespread practical use only in the 1970’s.
The main type of photomap is the topographic photomap, for which the same projection, system of drawing lines, notation, scales, precision, and symbols used for topographic maps are employed. Both black-and-white and, to a lesser extent, color photomaps are made in the USSR. Black-and-white photomaps are halftone controlled photomosaics with abridged symbolization; that is, geodetic points, hydrography, contour lines, main roads, political boundaries, and geographic names are shown, but the boundaries of populated and agricultural areas are not marked. Such photomaps are intended for use in any region, preferably in a set that also includes coventional topographic maps. Color photomaps consist of all the standard map symbols and a photographic image that is colored in different hues to show, for example, vegetation, soils, cultivated lands, and the development of populated areas. Color photomaps are recommended for use in regions with diverse landscapes, where such photomaps may be more useful than topographic maps.
Photomaps may be reproduced by printing or by photography; if photography is used, the map symbols are drawn in black or in white on a gray photographic background. For studies of various categories of features, a single-sheet photomap may be replaced by a two-sheet photomap. The latter consists of a base sheet, which is compiled from several sheets and which carries the photographic image of the locale and the geographic names, and a changeable transparent plastic overlay, which contains the various map symbols. Experimental photomaps include stereoscopic photomaps, which are intended for three-dimensional viewing of a territory with the aid of stereoscopes, and “talking” photomaps, which include magnetic tapes and numbered tests that provide supplementary information about selected parts of the map.
Two types of photomaps are published in the USSR, in accordance with the requirements of the national economy: general geographic maps and specialized maps. Specialized photomaps contain map symbols that are of importance only to a certain branch of the economy or to a group of related branches. The most widely used specialized photomaps are small-scale topographic photomaps, which are intended for geological prospecting; medium-scale photomaps, which are used for land reclamation and agriculture; and large-scale photomaps, which are intended for urban planning.
Photomaps are useful for two reasons. In some cases, they can be compiled and used considerably sooner than a full set of topographic surveys can be completed. In other cases, when used together with conventional maps, photomaps make it possible to improve the quality and substantially reduce the amount of expensive planning and surveying.
Photomaps are made by the map-making methods used in topography, primarily on the basis of photographs taken in the most recent aerial surveys. Photomaps compiled from space and underwater photographs obtained by direct photography or by remote scanning are being used with increasing frequency.
REFERENCESSozdanie topograficheskikh fotokart. Moscow, 1972. (Tr. Tsentr. n.-i. in-ta geodezii, aeros’emki i kartografii, fasc. 194.)
Rukovodstvo po sozdaniiu topograficheskikh fotokart. Moscow, 1974.
Gol’dman, L. M. “O naznachenii, soderzhanii i osobennostiakh izgotovleniia fotokart.” Geodeziia i kartografiia, 1975, no. 1.
Kienko, Iu. P. “Problemy kosmicheskogo prirodovedeniia.” Geodeziia i kartograffia, 1976, no. 4.
Proceedings of the International Symposium on Photo Maps and Orthophoto Maps (held in Ottawa, Canada, 1967). The Canadian Surveyor, 1968, vol. 22, no. 1.
L. M. GOL’DMAN