小型GNSS受信機および測位演算プログラムパッケージ「RTKLIB」による対空標識の簡易・高精度測位手法に関する事例研究

抄録

In order to accurately and inexpensively fix the location of ground control points for drone remote sensing, we tested the precision of post-processing static (PPS) calculations using a compact GNSS receiver (Reach RTK) and an open-source GNSS post-processing program package (RTKLIB). GNSS fix tests were carried at 3rd order survey points and other ground markers in Joso City and Tsukuba City in Ibaraki Prefecture, Japan. Tests using GNSS antennas of different reception sensitivity found that the most inexpensive antenna provided with Reach RTK was sufficient for precise positional measurements. This paper compares two methods for obtaining the final PPS calculation. In method 1, the last fix calculated was used as the final fix position. In method 2, the final fix position was calculated as the median value of all intermediate fix estimates. The tests found that method 2 was able to reduce GPS fix variability during observation because it could avoid the effects of temporary fix errors or erroneous calculations. In 60-minute observation sessions, the RMSE around the true position using method 2 was 2.7cm in the horizontal direction, and 1.2cm in the vertical direction. The GNSS devices used in this test achieved errors at levels of a few centimeters, more than sufficient for fixing the position of ground markers used for georeferencing drone remote sensing imagery. The method used here showed superior start-up costs (low equipment purchase costs) and running costs (no access costs for GNSS post-processing data) compared to existing GNSS devices or GNSS-equipped ground markers, and can serve as relatively inexpensive and powerful tools for supporting research using drone remote sensing.