Effect of Camera Calibration Refreshing on Orthophoto Position Accuracy in UAV Mapping

Abstract

Unmanned aerial vehicles (UAVs) are autonomous or remote control controlled air vehicles without a pilot. UAVs are aerial platforms capable of carrying non-metric photogrammetric equipment. In this study; the effect of two different calibration values of the camera available on the DJI Phantom 4 Pro equipment to the ortho-photo maps obtained from two different flight heights was investigated. An area within the campus of Gebze Technical University was chosen as a study area. PI 3000 software was used to calibrate the camera and the differences between the calculated parameters and the conventional parameters were determined. Also, the effect of the parameters on position accuracy was investigated. In the photogrammetric stereo model, the rms of Z depends on the picture scale, flight height, base length and the measurement accuracy of image coordinates. Since the measurement accuracy of the image coordinates x, y is also affected by the calibration accuracy, the calibration field independent of the Z value can be used. Geo-referencing and field measurements of the orthophotos produced by the GPS and measurement of the work area from two different heights with UAVs. Office work is the part where orthophotos are produced, georeferenced and analyzed with GPS coordinates of control points. The data obtained in the study reduces the rms value when recalibration is performed at a low flight altitude. However, a similar result could not be obtained for 120 meters flight altitude.