title: Development and Evaluation of a UAV-Photogrammetry System for Precise 3D Environmental Modeling.
abstract: The specific requirements of UAV-photogrammetry necessitate particular solutions for system development, which have mostly been ignored or not assessed adequately in recent studies. Accordingly, this paper presents the methodological and experimental aspects of correctly implementing a UAV-photogrammetry system. The hardware of the system consists of an electric-powered helicopter, a high-resolution digital camera and an inertial navigation system. The software of the system includes the in-house programs specifically designed for camera calibration, platform calibration, system integration, on-board data acquisition, flight planning and on-the-job self-calibration. The detailed features of the system are discussed, and solutions are proposed in order to enhance the system and its photogrammetric outputs. The developed system is extensively tested for precise modeling of the challenging environment of an open-pit gravel mine. The accuracy of the results is evaluated under various mapping conditions, including direct georeferencing and indirect georeferencing with different numbers, distributions and types of ground control points. Additionally, the effects of imaging configuration and network stability on modeling accuracy are assessed. The experiments demonstrated that 1.55 m horizontal and 3.16 m vertical absolute modeling accuracy could be achieved via direct geo-referencing, which was improved to 0.4 cm and 1.7 cm after indirect geo-referencing.
authors.affiliation: Department of Applied Geomatics, Université de Sherbrooke, 2500 Boulevard de l'Université, Building A6, Sherbrooke, QC J1K 2R1, Canada. mozhdeh.shahbazi@usherbrooke.ca.
authors.forename: Mozhdeh
authors.initials: M
authors.lastname: Shahbazi
authors.affiliation: Department of Earth and Space Science and Engineering, York University, 4700 Keele Street, Petrie Science & Engineering Building, Toronto, ON M3J 1P3, Canada. gsohn@yorku.ca.
authors.forename: Gunho
authors.initials: G
authors.lastname: Sohn
authors.affiliation: Department of Applied Geomatics, Université de Sherbrooke, 2500 Boulevard de l'Université, Building A6, Sherbrooke, QC J1K 2R1, Canada. jerome.theau@usherbrooke.ca.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Théau
authors.affiliation: Centre de géomatique du Québec, 534 Jacques-Cartier Est, Building G, Chicoutimi, QC G7H 1Z6, Canada. pmenard@cgq.qc.ca.
authors.forename: Patrick
authors.initials: P
authors.lastname: Menard
mesh_terms: D002138:Calibration; D004784:Environmental Monitoring / Q000379:methods*; D004867:Equipment Design; D062305:Geographic Mapping; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010780:Photogrammetry / Q000379:methods*
keywords: UAV; calibration; georeferencing; ground control point; mine; modeling; photogrammetry