AUTOMATIC ESTIMATION OF ALTITUDE OF THE REFERENCES POINTS FOR AERIAL AUTONOMOUS NAVIGATION USING AERIAL PHOTOGRAPHS AND CHARACTERISTIC POINTS

Abstract. The use of computer vision techniques to solve problems related to estimation of position has increased in recent decades due to rapid technological and computing develop-ment. This paper presents an approach to obtain position information of an Unmanned Aerial Vehicle (UAV) based on aerial images. The problem addressed is to allow a UAV to be locat-ed above ground. The considered vehicle has an inertial navigation system (INS) and receives no assistance of a satellite navigation system. Due to the inherent errors of the INS that cause disorientation of the UAV, an image-tracking system is proposed. The proposed methodology has been to build, in real-time and embedded, a Digital Elevation Model of reference points (DEM-R) to allow a vehicle to locate in the ground based on the comparison between this and pre-existing model. In order to achieve this objective it is necessary to identify similar points in sequential images and calculate the altitude of these points. This enables build the DEM-R. We used the SIFT techniques and Zernike moments to identify similar points. We used aerial imagery of the city of Sao Jose dos Campos- Sao Paulo- Brazil, with longitudinal coverage of 60%. The obtained results show that the methodology is viable to the proposed problem, autonomous navigation of UAVs