The compilation of a reconnaissance map of Alexander Island, Antarctica, from trimetrogon air photographs
Few would deny that the advent of the aerial photograph caused a major revolution in surveying, or that the mapping of large areas at topographical scales,is most profitably done by a systematic coverage of vertical air photographs and an adequate system of ground control. In our student days, how many times were we told that an aerial photograph is not a map as far as the surveyor is concerned, the implication being that without that adequate ground control the photographic coverage may be dismissed as being near to useless. And yet there must be large areas of the earth's surface for which air photograph cover exists but for which no ground control has ever been obtained—areas “on which the hand of man has never set foot”. Large tracts of the Antarctic come into this category; during and since the, war many Antarctic expeditions, particularly American, have flown photographic sorties which must amount to many thousand miles in toto, and the resulting photographs have remained in their storage boxes for up to twenty years largely because no ground control was ever established. Generally the position of the base from which the aircraft were operated was known accurately enough, but without landing a surveyor for a long enough period to fix by astronomical means features which appeared on the photographs, or by flying the sorties in close conjunction with independent ground survey teams, these expeditions could add little to the maps of the areas over which they flew. Usually all that resulted from many undoubtedly, well-intentioned flights were several thousand more fine photographs and a cover diagram of a system of flight lines radiating from a central base camp. Generally these flight diagrams have been drawn at a scale of one to several million, since few have had the courage to finalise the plotting of flight lines from such notoriously unreliable information as a flight record of magnetic compass bearing and air speed.