surveying, mapping (map), and aerial photography agency of the Overseas Development Administration (ODA) of the United Kingdom, founded in 1946 to provide advice to the ODA and foreign governments and organizations on technical matters concerning all aspects of surveying and mapping. The maps are produced by modern aerial photography and photogrammetric methods. Aerial photography missions are flown mainly by air survey companies of the United Kingdom, and directorate surveyors are sent overseas to establish horizontal and vertical ground control for the photography. Survey control is permanently marked and coordinated so that the surveys may form the basis for future work. After maps are compiled from the aerial photography, plots of the maps are checked and annotated by the local survey department. Final maps are drawn at directorate headquarters and printed by the Ordinance Survey of Great Britain. The directorate's technical libraries provide facilities for consultation of survey data and maps of the countries in which the directorate has worked. The directorate also disseminates information on new techniques and equipment in the fields of surveying, photogrammetry, and cartography.