Analysis and Design of Protocol for the Reconstruction of Computer Field Model Using Dron and Photogrammetry

Abstract

One of the main challenges in aerial photogrammetry is the lack of standardization in the process of data integration, which is the first step in 3D reconstruction. This study analyses the influence of the distance from the camera to the subject of the recording, the influence of different overlap percentages in photography as well as the difference between the three methods of re-cording in programming flight plans. DJI Phantom 3 unmanned aerial vehicle and PIX4Dmapper software for 3D reconstruction were used in this research. The old town of Medvedgrad near Zagreb, Croatia was the subject of recording. The purpose of this study is to design a standardized image recording protocol that would contribute to a faster and more optimal workflow while maintaining a quantitatively measured quality according to the total number of 2D key points per image and the total number of 3D key points in a point cloud. Based on research and the obtained results, the possibility of data recording at a distance of up to 30 m without a significant loss (3.6%) of the number of 2D key points per photograph was proven. A larger horizontal distance allows recording from one viewing altitude if the height of the subject does not exceed 30 m. This study determines that 85% image overlap results in an almost identical number of 3D key points (0.7% difference) as well as 90% image overlap. The authors proposed a new flight plan, which would implement optimized parameters obtained in this research.