Image mosaicking and aerial triangulation accuray analysis from five camera imaging system equipped by high payload fixed-wing UAS

Unmanned aerial system (UAS) has advantage of higher mobility and lower risk comparing with manned airplane. However, most UAS were restricted by its low payload, small capacity and short endurance time thus can only carry one single small format camera for small area investigation. In this study, a five small format DSLR cameras composed imaging system is proposed and mounted on a high payload UAS for large coverage image collection. In which, one nadir and four oblique views imagery were acquired at the same time and mosaicked into larger format image to enlarge ground coverage, increase the imaging geometric strength and overall positioning accuracy. The multi-image mosaicking algorithm is first derived the projective transformation coefficients and interior orientation parameters from indoor camera calibration. To analyze the co-registration residuals between the overlapped areas of two neighbored images, two systematic errors, i.e. scale and displacement, are obtained and applied to refine the image mosaicking results. Accuracy analysis was performed by conventional aerial triangulation procedure. Result shows that the mosaicked image can achieve sub-pixel accuracy. Meanwhile, its absolute positioning accuracy can also meet the 1/1000 topographic mapping standard.