two major U.S. Geological Survey (USGS) digital data file structures. DLG is line map information in digital form. These files include information on planimetric base categories, such as transportation, hydrography, and boundaries. DEM files consist of a sample array of elevations for a number of ground positions that are at regular spaced intervals.
A commonly used format and standards for transferring vector data developed and published by the USGS.
(DLG) A vector file containing points, lines, and/or areas that represent roads, water bodies, topographic contour lines, public lands, and railroads. Each data layer comes in a separate file. The DLG format was created by the USGS. See Also: vector