GPS KINEMATIC CARRIER PHASE MEASUREMENTS FOR AERIAL PHOTOGRAMMETRY

GPS kinematic positioning with carrier phase measurements is an effect ive method that can acquire required point accuracies for aerial photo grammetry. From late April to early May, 1994, airborne GPS carrier ph ase measurements with multi-reference stations were executed with four Trimble 4000SST receivers and an airborne Wild RC20 camera on board a Lear 36A Jet aircraft. The airborne GPS data were sampled at the flig ht altitudes of 0.45, 2.3 and 10.8 km. The furthest distance reached i n the flight operation from the reference station was 453 km. It is kn own from the precision of the closure of the kinematic figure that GPS test data gathered at these three altitudes are of a high quality, so that tile real-time positions and 3D velocities of the airborne GPS a ntenna can be solved accurately by our DDKIN software. This paper desc ribes the air test results and discusses the practical problems of acc urately surveying with airborne GPS.