Comparison the Plane Precision of UAS Aerial Survey Between Image Processing and GNSS Measuring Data

Based on MVS/SfM of the image processing technology, UAS photogrammetry is able to produce high precision orthophoto. The inner precision data of orthophoto can be provided after aligning photo in precision report, including ground resolution of the total image, the RMSE of control point and checkpoint by image processing software. However, while measuring the coordinates of image point from orthophoto in surveying project, we cannot realize the real amount of error from report. For obtaining the real amount of error when measures image coordinates from the orthophoto, this study conducted e-GNSS measurements on the control points, check points and feature points selected from the image. And compare the coordinates of the image measurement with the measured coordinates. The result finds out that the average deviation of control points is about 2.9 cm, the average deviation of check points is about 4.0 cm, the average deviation of feature point is about 6.1 cm. The data of feature point shall be taken as reference in project, for decreasing deviation, shall decrease image deviation in prior concern.