Georeferencing High-Altitude Aerial Imagery.

High-altitude balloons (HAB), allied with flying-wing unmanned aerial vehicles (UAV), may play an important role in fire monitoring. Due to their aerostatic lift, a HAB may effortlessly carry an UAV to reach higher altitudes and therefore survey a wider area. Considering high-altitude UAV acquired imagery, this work presents a direct georeferencing method based on the geolocation algorithm, that consists on computing the pose of the camera with respect to the ground followed by the mapping between a 3D point and a 2D image pixel using the projection equation. Real-flight data covering diverse situations is used for evaluating the algorithm performance. The complementary filter is used on the measurements from the payload sensors to compute the necessary parameters for the direct georeferencing.