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http://dx.doi.org/10.7848/ksgpc.2017.35.6.563

Acquisition of Subcentimeter GSD Images Using UAV and Analysis of Visual Resolution  

Han, Soohee (Dept. of Geoinformatics Engineering, Kyungil University)
Hong, Chang-Ki (Dept. of Geoinformatics Engineering, Kyungil University)
Publication Information
Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography / v.35, no.6, 2017 , pp. 563-572 More about this Journal
Abstract
The purpose of the study is to investigate the effect of flight height, flight speed, exposure time of camera shutter and autofocusing on the visual resolution of the image in order to obtain ultra-high resolution images with a GSD less than 1cm. It is also aimed to evaluate the ease of recognition of various types of aerial targets. For this purpose, we measured the visual resolution using a 7952*5304 pixel 35mm CMOS sensor and a 55mm prime lens at 20m intervals from 20m to 120m above ground. As a result, with automatic focusing, the visual resolution is measured 1.1~1.6 times as the theoretical GSD, and without automatic focusing, 1.5~3.5 times. Next, the camera was shot at 80m above ground at a constant flight speed of 5m/s, while reducing the exposure time by 1/2 from 1/60sec to 1/2000sec. Assuming that blur is allowed within 1 pixel, the visual resolution is 1.3~1.5 times larger than the theoretical GSD when the exposure time is kept within the longest exposure time, and 1.4~3.0 times larger when it is not kept. If the aerial targets are printed on A4 paper and they are shot within 80m above ground, the encoded targets can be recognized automatically by commercial software, and various types of general targets and coded ones can be manually recognized with ease.
Keywords
UAV; Flight Height; Flight Speed; Exposure Time; Autofocusing;
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Times Cited By KSCI : 4  (Citation Analysis)
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