Analysis of topographic surveys using a GNSS receiver and a drone equipped with a LiDAR sensor in the study of the Yagbé-Aholouyèmè road section and the railway bridge of Porto-Novo in Southern Bénin

Abstract

The advent of drones and global navigation satellite systems (GNSS) has significantly transformed topographic data collection, offering increased accuracy and efficiency compared to traditional methods. The study was based on aspects of topographic surveys by GNSS receiver and drone with onboard LiDAR sensors, such as data accuracy, survey time, conditions of use, associated costs, and material quality on a road located in the commune of Seme-Podji called the Yagbé-Aholouyèmè section and the Porto-Novo rail bridge in order to obtain data from GNSS receiver surveys and an orthophoto of the area concerned. The topographic data was mainly acquired using an eSurvey E800 GNSS receiver and a DJI Phantom 4 Pro V2 photogrammetric drone. For the Porto-Novo Bridge, additional data was collected using a Matrice 300 RTK drone equipped with a LiDAR sensor. Data processing involved Agisoft Metashape for the generation of orthophotos and DTMs, Surfer software for 3D surface models and Autocad-Covadis for longitudinal profiles of natural terrain. Ground control points (GCP) ensured accurate georeferencing. The results showed that the section had a critical slope and required rehabilitation work. With the drone photogrammetry technology, the surveys were accurate. When the drone was equipped with a lidar sensor, the surveys had very high accuracy. The study demonstrates the importance of using modern technologies for collecting and analyzing topographic data. It confirms that while drones are suitable for rapid and medium-scale surveys, the integration of GNSS remains essential for optimal accuracy at critical points, advocating a combined strategy for highly accurate and efficient topographic projects.