GPU-based Orthorectification of Digital Airborne Camera Images in Real Time

Abstract

The usage of airborne camera systems for near real time applications will increase in the near future. This paper purposes a new hardware/software architecture to establish real time computation of images obtained from the DLR wide area airborne 3K-camera system. The main applications of our system are e.g. to monitor automotive traffic, to determine the workload of public road networks during mass events, or to obtain a survey of damages in disaster areas in real time. Therefore, many different image processing tasks have to be executed in real time. Orthorectification of images is necessary prior to all other processing tasks, e.g. before mapping data from street data bases into images or before tracking of vehicles. Nowadays, the calculation becomes possible due to fast graphic processing units (GPU) and with the support of a distributed real time system. In order to achieve real time image processing, we suggest a GPU-based algorithm for image orthorectification. The GPS/IMU-system provides the position and orientation of the aircraft with 128Hz quite accurately. Assuming synchronized measurements with the camera system and given camera calibration, direct orthorectification is implemented using OpenGL. Therewith, we are able to process high resolution images consisting of 16 MPixels with a frame rate of 3 Hz. This paper describes the implementation of the real time algorithm and gives first results.