Recent Advances in Kinematic GPS Photogrammetry

The National Ocean Service (NOS) has been pursuing the application of kinematics Global Positioning System (GPS) positioning to airborne instrumentation packages and photogrammetry in particular. Two partially successful experiments demonstrate that differential carrier-phase observations acquired by a GPS receiver aboard the airplane can support very precise aerotriangulation without any ground control. In these experiments aerial photography over an area of abundant ground control is acquired simultaneously with an uninterrupted set of differential GPS observations. The photogrammetric image data are employed in two aerotriangulation adjustments, one with the ground control, the other with only the GPS data. In both experiments, the rms of the discrepancies between the camera positions computed by the two adjustments is just over 5 cm in each coordinate. Discrepancies in the computed ground points are even smaller, but this is due in part to the large scale of the photography (1:3,000).