What is a "Digital Elevation Map"? The Most Authoritative Explanation.
What is a Digital Elevation Model (DEM)?
A Digital Elevation Model (DEM) is a representation of the bare ground (bare earth) topographic surface of the Earth excluding trees, buildings, and any other surface objects. DEMs are created from a variety of sources. USGS DEMs used to be derived primarily from topographic maps .Where can I find elevation data?
Digital elevation data for the United States and its territories are available through The National Map Downloader. Click the “Help” link at the top of the page for detailed instructions on how to find and download data. There is a separate site for The National Map Services.What is the new elevation map service?
The new elevation map service creates multi-resolution visualizations on-the-fly, allowing users to explore a variety of representations including: hillshade; aspect; slope; and tinted hillshade maps, as well as automated contours and more.How do mappers prepare digital elevation models?
Mappers may prepare digital elevation models in a number of ways, but they frequently use remote sensing rather than direct survey data. Older methods of generating DEMs often involve interpolating digital contour maps that may have been produced by direct survey of the land surface.
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