EFFECT OF ENLARGEMENT OF A PHOTOGRAPHIC IMAGE ON SOME MEASURING PROPERTIES OF AERIAL PHOTOGRAPHS,
ARMY ENGINEER RESEARCH AND DEVELOPMENT LABS FORT BELVOIR VA
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An aerial photograph enlarged to the scale 1M, and obtained from an aerial negative taken from a great height, in many respects has better measuring properties than does a contact print from an aerial negative taken directly in the scale 1M from a lower height. It is more feasible for the contour and composite surveys to conduct the photographing from as great a height as possible, taking into account the maximum enlargement ratio at which a satisfactory photographic quality of the aerial negatives is obtained. It is possible to conduct aerial photographing to large and medium scales of surveying, figuring on a subsequent magnification of the aerial photographs by 4 - 8 times. In addition, in many cases, the various establishments can successfully utilize the already available aerial negatives from prior surveys with an enlargement of the photo-image by 3 - 4 times, and sometimes even more. The enlargement ratios will increase in value in proportion to the development of science and technology. The use in production of high enlargement ratios for a photo-image will permit us to raise appreciably the output and economy of the aerial photogeodetic operations in contour and composite surveying without a decrease in the accuracy of the maps and charts.