ACCURACY ASSESSMENT OF ELEVATION DATA SETS USING THE GLOBAL POSITIONING SYSTEM

A field survey using the Global Positioning System (GPS) was performed to evaluate the accuracy of a prototype data set called Tactical Terrain Data (TTD). The horizontal and vertical accuracy of a 1:24,000-scale 7 1/2-minute quadrangle, a 1:50,000-scale 15-minute quadrangle, and two Digital Elevation Models (DEMs) were also assessed. Nineteen road intersections located in the study area were tied to three first-order horizontal control stations using relative GPS static and pseudo-kinematic techniques. The coordinates and elevations of the 19 road intersections obtained from the TTD, DEMs and topographic map sheets were compared to the GPS data in both an absolute and relative sense. The TTD did not meet stated absolute accuracy requirements, while the relative accuracy was found to be satisfactory. The DEMs and the map sheets were of high vertical quality and met stated vertical accuracy standards.