Photogrammetry
Photogrammetry is the art and science of obtaining reliable measurements by photography (metric photogrammetry) and qualitative evaluation of image data (photo interpretation). It includes use of terrestrial, close-range, aerial, vertical, oblique, strip, and space photographs along with their interpretation.
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Stadia Surveying
Measurement of distance with tapes
Reasonable precisions for different methods of measuring distances are
Pacing (ordinary terrain): 1 /50 to 1 /100
Taping (ordinary steel tape): 1 /1000 to 1 /10,000.
Baseline (invar tape): 1 /50,000 to 1/ 1,000,000
Stadia: 1 /300 to 1 /500
Subtense bar: 1 /1000 to 1/ 7000
Due to the technological upgradation and invention of Electronic distance measurement (EDM) devices,steel tapes are being largely replaced with them on large projects. But still knowledge of steeltaping errors and corrections remains important,
For ordinary taping, a tape accurate to 0.01 ft (0.00305 m) should be used. The tension of the tape should be about 15 lb (66.7 N). The temperature should be determined within
10°F (5.56°C); and the slope of the ground, within 2 per- cent; and the proper corrections, applied.
Units of Measurement
Units of measurement used in past and present surveys are
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