Development of a Large-Format UAS Imaging System With the Construction of a One Sensor Geometry From a Multicamera Array

For the purpose of large-area topographic mapping, this study proposes an imaging system based on a multicamera array unmanned aerial system (UAS) comprised of five small-format digital cameras with a total field of view of 127°. The five digital cameras are aligned in a row along the across-track direction with overlap between two neighboring cameras. The suggested system has higher data acquisition efficiency than the single-camera UAS imaging system. For topographic mapping purposes, we develop a modified projective transformation method to stitch all five raw images into one sensor geometry. In this method, the transformation coefficients are obtained by on-the-job multicamera self-calibration, including interior and relative orientations. During the stitching process, two systematic errors are detected and corrected. In the end, a large-format digital image can be produced for each trigger event independently. The photogrammetric collinearity condition is evaluated using several external accuracy assessments, such as conventional aerial triangulation, stereoplotting, and digital surface model generation procedures. From the accuracy assessment results, we conclude that the presented raw image stitching method can be used to construct a one sensor geometry from a multicamera array and is feasible for 3-D mapping applications.