Manual profiling from photogrammetric stereomodels using stereoplotters equipped with three-axis electronic digital profile recording modules, by scanning stereomodels along successive terrain profiles. Interpolation of the elevations from stereomodel digitized contours, derived from stereoplotters equipped with three-axis digital recording modules. All data now being generated use this process. Spatial Resolution DEM data are stored as profiles in which the spacing of the elevations along and between each profile is 30 meters. The number of elevations between each profile will differ because of the variable angle between the quadrangle's true north and the grid north of the UTM coordinate system.
Test points are well distributed and representative of the terrain.
For general information on accuracy, see Horizontal Positional Accuracy and Vertical Positional Accuracy . A record contains information defining the general characteristics of the DEM, including DEM name, boundaries, units of measurement, minimum and maximum elevations, number of Type B records, and projection parameters. Type A record per DEM file. Record Type B contains profiles of elevation data and associated header information. There is a Type B record for each profile.