Modular Photogrammetric Sensor Systems for Real-time Information Extraction and 3D-Applications

Abstract

To enable research in the field of real-time information extraction and precise 3D reconstruction from aerial remote sensing data, a set of experimental sensor systems has been developed at the DLR Institute of Optical Sensor Systems. The Modular Airborne Camera System (MACS) stands for the concept of a highly flexible photogrammetric sensor system. It consists of a set of calibrated camera heads, a commanding unit and auxiliary measuring devices e.g. for position and orientation. The processing unit simultaneously operates up to 6 camera heads and handles the data processing, storage and output to a real-time data-downlink. The geometric flexibility is expressed by the possibility to rapidly change the geometric configuration for oblique or wide-swath imaging. Also the spectral range can be adapted, cameras recording visual, near infrared and thermal infrared light as well as hyperspectral sensors can be operated simultaneously. To be able to use a wide range of carriers a further design concept is low weight and small size. Systems have been integrated in (wing)pods (e.g. Stemme S10, Tornado), in standard aircraft and in fixed-wing as well as in multi-rotor UAVs. A high level of autonomy is reached by using a GPS-based fully automatic image acquisition. A rigid and determinable alignment of sensors, optics, position and orientation measurement systems as well as an extensive geometric and radiometric calibration is essential for the photogrammetric 3D capability of the system. It has been developed and verified in several instances over the last years. Industrial grade sensors delivering high frame rates allow very high overlaps of all sensors even at high flight velocities what qualifies MACS especially for 3D-reconstruction of oblique image flights over urban areas. An in-house developed operating software is used in all MACS sensor systems and provides images with an exact timestamp, position and orientation information to ensure an consistent photogrammetric workflow. Main fields of application of the MACS system so far have been real-time monitoring and information extraction for security applications, full 3D data acquisition for simulation purposes, especially in urban scenarios and 2,5D mapping even under extreme conditions in the Himalayas.