ASSESSING THE ACCURACY OF DIGITAL ELEVATION MODEL GENERATED FROM UNMANNED AERIAL VEHICLE (UAV) IMAGERY : FOR THE COAST BEACH

Abstract

The Unmanned Aerial Vehicle (UAV) technology is becoming useful to generate a Digital Elevation Model (DEM). Aerial triangulation is the basic method for analyzing UAV images in order to generate the DEM. The aerial triangulation method effectively calculates the 3-dimensional coordinates of object points of images. For more accurate results of DEM and ortho-rectified image, camera calibration is necessary. The DEM generated from this method needs to 3-dimensional (x, y, z) verification. The first purpose of this study is quantitative evaluation of the DEM by changing the number of Ground Control Point (GCP) measured by Real Time Kinematic-GPS (RTK-GPS). The second purpose is overlap (%) degree analysis of the images acquired from UAV. The study site is eastern coast beach of the Korean Peninsula. In this study, we used a rotary-wing UAV (width: 90 cm payload: 3 kg flight speed: 10 km/h flight height: 50-700 m flight duration: 15 min). The study site is covered by natural features such as sand, gravel and vegetation that do not provide defined points to be used as GCPs. In order to obtain accurate results of the DEM, several GCPs are needed. However, the optimum number of GCP has not been defined in detail. To get an effective number of GCP, DEMs with different number of GCP were compared. In addition, various overlap degree analysis of the images was performed from different flight paths. In order to evaluate thectively calculates the 3-dimensional coordinates of object points of images. For more accurate results of DEM and ortho-rectified image, camera calibration is necessary. The DEM generated from this method needs to 3-dimensional (x, y, z) verification. The first purpose of this study is quantitative evaluation of the DEM by changing the number of Ground Control Point (GCP) measured by Real Time Kinematic-GPS (RTK-GPS). The second purpose is overlap (%) degree analysis of the images acquired from UAV. The study site is eastern coast beach of the Korean Peninsula. In this study, we used a rotary-wing UAV (width: 90 cm payload: 3 kg flight speed: 10 km/h flight height: 50-700 m flight duration: 15 min). The study site is covered by natural features such as sand, gravel and vegetation that do not provide defined points to be used as GCPs. In order to obtain accurate results of the DEM, several GCPs are needed. However, the optimum number of GCP has not been defined in detail. To get an effective number of GCP, DEMs with different number of GCP were compared. In addition, various overlap degree analysis of the images was performed from different flight paths. In order to evaluate th