DIRECT GEOREFERENCING USING GPS/INERTIAL EXTERIOR ORIENTATIONS FOR PHOTOGRAMMETRIC APPLICATIONS

One crucial point during the application of direct georeferencing is the accuracy and reliability of directly measured orientation parameters using integrated GPS/inertial systems in an operational photogrammetric airborne environment. In order to investigate the potential of direct georeferencing for standard photogrammetric applications the accuracy of a commercially available GPS/inertial system (Applanix POS/DG 310) is evaluated. For that purpose a well controlled airborne test comparing the results from standard bundle adjustment and point determination by direct georeferencing is described. Within this test special focus is given on the quality of the GPS/inertial exterior orientation using several master stations with varying baseline length up to 380km. Additionally, the influence of variable image overlap on the resulting object coordinates is investigated. Although very consistent and high accuracy in object space is proved using direct georeferencing, the tests show the great importance of proper calibration between GPS/inertial and camera components. From this point of view, the integration of the GPS/inertial exterior orientations in a combined aerial triangulation provides the most flexible approach and is recommended for highest photogrammetric accuracy demands.