This project required survey & mapping services meeting Federal Emergency Management Agency floodplain mapping specifications of a 190-square-mile area located 30 miles west of Phoenix. The project abuts previous mapping completed by Wilson & Company for Maricopa County. Ground control and mapping data from the previous project were seamlessly integrated into the flight and control design, and subsequent mapping. The scope of services included photo control surveying, structure surveying, aerial photography, photogrammetry, and development of HIS compliant geographic information systems (GIS) coverage. Aerial photography was flown at 3,600-feet above mean terrain (AMT) using airborne GPS with an inertial measurement unit (IMU) to supplement and reduce ground control. Blind panels were placed within the project limits to be measured by Wilson & Company photogrammetrists during the aerotriangulation process. The coordinates for the blind panels were analyzed by an independent surveyor and provided to the Flood Control District for comparison to Wilson & Company’s measured values. The resultant root mean square error (RMSE) was extremely tight.
