INS-camera calibration without ground control points

In this paper we present an approach for performing system calibration of a sensor suite consisting of a fixed mounted camera and an inertial navigation system without the usage of a photogrammetric calibration site. The aim of the presented work is to obtain accurate direct georeferencing of camera images collected with manned or unmanned aerial systems for search and rescue tasks. These time-critical missions require a straightforward calibration which can be performed without additional equipment. This induces an in-flight calibration of the intrinsic camera parameters in addition to the mounting offsets between the camera and the inertial navigation system. The optimization of these values can be done by introducing them as parameters into a bundle adjustment process. We show how to solve this by exploiting a graph optimization framework. The evaluation of the proposed approach with data from flight experiments leads to an improvement of roughly factor six compared to a terrestrial calibration.