Coplanar condition and reverse correction based direct georeferencing of unmanned aerial vehicle images

A direct georeferencing method based on coplanar condition and reverse correction for unmanned aerial vehicle (UAV) images is proposed in this research. The main contributions of the method are embodied in three aspects. Firstly, a dual-step georeferencing algorithm based on coplanar condition is presented, which uses the analytic method to obtain the space position information of the target by two steps of relative orientation and absolute orientation according to the overlap and coplanar characteristics of UAV continuous images. Secondly, based on the coplanar condition georeferencing algorithm, this method introduces the idea of reverse rectification, and the georeferencing accuracy is transmitted from the current frame to the back frame according to the overlap relation between frames, which can effectively improve the attitude accuracy of the back image. Thirdly, a mediumaltitude UAV is employed to collect large amount of images and other telemetry data. Then the method contrast experiments are designed and performed. The results are analyzed and discussed, and present quite encouraging.