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
A file or data structure from the US Geological Survey (USGS) that includes digital non-topographic information from the USGS map base categories such as transportation, hydrology, and public land survey boundaries.
USGS product that includes digital information from the USGS map base categories, such as transportation, hydrography, contours, and public land survey boundaries.
A computer file format for mapping data that provides a topological structure to describe points, lines and polygons. A DLG may contain lists of point coordinates describing boundaries, drainage lines, and other linear or area features, which are organized by USGS quadrangle areas. These data are the digital equivalent of the linear hydrographic and cultural data on a topographic base map. The flood risk thematic layers developed by FEMA will fit the quadrangle as an overlay. The U.S. Geological Survey Digital Line Graph Level 3 Optional format has been adopted by FEMA for the purposes of the National Flood Insurance Program mapping and engineer requirements. Level 3 data files are fully topologically structured and are designed to be integrated into GISs.
1. In reference to data, the geographic and tabular data files obtained from the USGS that may include base catagories such as transportation, hydrography, conours, and public land survey boundaries. 2. In reference to data format, the formal standards developed and published by the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format.
U. S. Geological Survey digital map format used to distribute topographical maps in vector form.
In reference to data, the geographic and tabular data files obtained from the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format.6 In reference to data, the formal standards developed and published by the USGS for exchange of cartographic and associated tabular data files. Many non-DLG data may be formatted in DLG format.6
A comprehensive topological vector format data structure developed by the U.S. Geological Survey. Often referred to as DLG, DLG-3, or DLG Optional format. Used for storing and distributing digital data.
