Development and Evaluation of a UAV-Photogrammetry System for Precise 3D Environmental Modeling

TLDR

The specific requirements of UAV‑photogrammetry demand tailored solutions for system development, a need largely overlooked in recent studies. This paper presents the methodological and experimental aspects of correctly implementing a UAV‑photogrammetry system. The system combines an electric‑powered helicopter, a high‑resolution camera, and an inertial navigation system, with custom software for calibration, integration, data acquisition, flight planning, and self‑calibration, and was tested on an open‑pit gravel mine under various mapping conditions to assess accuracy and the effects of imaging configuration and network stability. Direct geo‑referencing achieved 1.55 m horizontal and 3.16 m vertical absolute accuracy, which improved to 0.4 cm horizontal and 1.7 cm vertical after indirect geo‑referencing.

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.