DIRECT GEOREFERENCING IN UNMANNED AERIAL VEHICLE USING QUASI-ZENITH SATELLITE SYSTEM

Abstract

To produce accurate topographic data, Unmanned Aerial Vehicle (UAV) still rely on Ground Control Points (GCPs) for georeferencing. However, using GCPs has several limitations, among others, related to the cost and time required for field measurements. In addition, not all areas are accessible for GCPs measurements due to poorly accessible terrain or security reasons. Direct georeferencing, a method to determine precise camera position and orientation in UAVs using Global Navigation Satellite System (GNSS) geodetic antenna. Post Processing Kinematic (PPK) or real-time coordinates can be applied to determine the camera position. One satellite that sends corrections to the rover on Earth is the Quasi-Zenith Satellite System (QZSS). This study aims to analyze the orthophoto accuracy of the results of direct georeferencing using precise coordinates from the QZSS satellites. The flight parameter was used at 60% sidelap and 80% overlap on an average flying altitude of 300 m above ground level resulting in 135 photos with a Ground Sampling Distance (GSD) value of 6 cm. The accuracy of direct georeferencing using QZSS horizontally and vertically was 1.134 m and 1.617 m, respectively. Meanwhile, the same metric results using conventional GCPs were 0.417 m horizontally and 0.419 m vertically. With these results, the horizontal accuracy of Direct Georeferencing using corrections from QZSS can be used for large-scale mapping of the 1: 5,000 class 1 scale, while vertical accuracy can be used for large-scale mapping of the 1: 5,000 class 3 scale. Direct georeferencing using QZSS corrections has the potential to support the acceleration of large-scale mapping activities in Indonesia.