The potential of low altitude aerial data for large scale mapping

Abstract

Unmanned Aerial Vehicle (UAV) system offers many advantages in several applications such as topographic mapping, thematic mapping, slope mapping, geohazard studies, monitoring, etc. This study utilizes UAV system for large scale mapping by using a digital camera attached to a fixed wing UAV. The main objective of this study is to explore the potential of UAV for large scale mapping and to evaluate the accuracy of the photogrammetric output produced from the UAV system. The UAV was used to acquire low altitude aerial photograph based on photogrammetric technique and subsequently accuracy assessment is performed. The Ground Control Points (GCPs) and Check Points (CPs) were established using GPS rapid static technique for photogrammetric data processing. The GCPs were used in to produce 3D stereomodel and other photogrammetric output while the CP is used for accuracy assessment. For digital image processing of the aerial photograph and map production, Erdas Imagine 8.6 software is employed. For accuracy assessment, the coordinates of the selected points in the 3D stereomodel were compared to the conjugate points observed using GPS and the root mean square error (RMSE) is computed. From this study, the results showed that the achievable RMSE are ± 0.510 m, ± 0.564 m and ± 0.622 m for coordinates X, Y and Z respectively. For this study, the digital map was also produced using the photogrammetric technique and it is compared with an engineering plan produced from ground surveying technique (i.e. total station). From this study, it can be concluded that accuracy of sub-meter is achieved using the UAV system. Also, this study demonstrates that the UAV system has the potential for large scale mapping in the field of surveying and other diversified applications, especially for small area, minimum budget and less manpower.