U.S. Geological Survey --EROS Data Center
Development of a 30-Arc-Second Digital Elevation Model of South America
Norman B. Bliss and Lisa M. Olsen, USGS EROS Data Center, Sioux Falls, SD 57198
e-mail: bliss@dg1.cr.usgs.govAbstract
A 30-arc second digital elevation model (DEM) of South America was developed using five different data sources. These data sources included: Digital Terrain Elevation Data (DTED) and Digital Chart of the World (DCW) from the Defense Mapping Agency, the International Map Chart of the World (ICW), topographic maps from the Army Map Service (AMS), and topographic maps of Peru. The DTED were generalized from a 3-arc-second resolution to a 30-arc-second resolution through systematic sampling. These data were used directly in the resultant data set. The remaining data types were processed using Australian National University's Digital Elevation Model (ANUDEM) software. This software iteratively applies a spline interpolation algorithm to the data, resulting in a gridded surface. Where conflicts between data sources arose, the most inconsistent data were excluded from ANUDEM processing.
The result is a raster data product. A graphic representation of the data is based on shading elevations by color, and blending a shaded relief view. This data set has 10 times more points along each line of latitude or longitude than the best continental data set previously available to the public (ETOPO5), representing a 100-fold increase of resolution on an areal basis. The accuracy of the grid is limited by the accuracy of the source materials. Furthermore, various artifacts in the data may be introduced through processing, including the creation of spurious hills and valleys and a stair-step procession in areas of gradually sloping topography. When possible, anomalous features were minimized by selecting or excluding input data and by localized editing of the results.