What is the difference between DEM data and NED data?
Both data sets express, essentially, the same resolution (30X30 meter spacing between elevation points). The main difference between the two data sets is that DEM data is based on the USGS 7.5 minute topo quads and the NED data is a seamless coverage of elevation coordinates for the entire U.S. Generally, each quad of DEM data needs to be fitted to its adjacent quads in order to eliminate the areas of no data between each quad. Please keep in mind that when you retreive DEM data from the USGS, that it will probable be in the SDTS format. Please visit our LINKS page for this data.
