Airborne GPS is a method, which drastically reduces the number of ground control points necessary on larger projects. When performing airborne GPS projects we install a geodetic quality GPS system in the airplane. The GPS receiver records an event marker from the camera, logging the precise time of each exposure station or photo center. This time record is then correlated to the location of GPS ground stations (at known, surveyed locations), which were recording during the flight. We have completed several Airborne GPS projects where minimal ground control is supplemented by precisely locating the camera's projection center in three dimensions.