An evaluation of DEM accuracy: elevation, slope, and aspect

The accuracy of elevations, slopes, and aspects were evaluated for two DEMs of an area centered on Blacksburg, Virginia, in the southern Appalachian Mountains. The first was a US Geological Survey (USGS) 7.5-minute quadrangle-based DEM with 30m postings, produced utilizing automated stereocorrelation of 140 000-scale leaf-off aerial photographs with a Gestalt Photomapper (GPM). The second DEM of the same area was produced from a SPOT panchromatic stereopair using a proprietary stereo-correlation technique developed by the STX corporation, among those used by SPOT Image Corp. for high resoultion DEM production. EM accuracy was assessed visually and through comparisons of DEM-derived to field-surveyed values for elevation, slope, and aspect. -from Authors