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The National Elevation Dataset (NED) consists of high precision topography or ground surface elevation data (digital elevation model) for the United States. It was maintained by the USGS and all the data is in the public domain. Since the 3D Elevation Program came online, the NED was subsumed [1] into The National Map as one of its layers of ...
A digital raster graphic (DRG) is a digital image resulting from scanning a paper USGS topographic map for use on a computer. DRGs created by USGS are typically scanned at 250 dpi and saved as a TIFF .
In 1995 the USGS was in need of a Windows viewer for their data products, so they developed the dlgv32 application for viewing their DLG (Digital Line Graph) vector data products. Between 1995 and 1998 the dlgv32 application was expanded to include support for viewing other USGS data products, including DRG (topographic maps) and DEM (digital ...
The Geospatial Data Abstraction Library (GDAL) is a computer software library for reading and writing raster and vector geospatial data formats (e.g. shapefile), and is released under the permissive X/MIT style free software license by the Open Source Geospatial Foundation.
The USGS DEM format is a self-contained (single file) set of ASCII-encoded (text) 1024-byte (1024 ASCII chars) blocks that fall into three record categories called A, B, and C. There is no cross-platform ambiguity since line ending control codes are not used, and all data including numbers is represented in readable text form.
Integrated Software for Imagers and Spectrometers (Isis) is a specialized software package developed by the USGS to process images and spectra collected by current and past NASA planetary missions sent to Earth's Moon, Mars, Jupiter, Saturn, and other solar system bodies.
Global Mapper handles both vector, raster, and elevation data, and provides viewing, conversion, and other general GIS features. In 1995 the USGS was in need of a Windows viewer for their data products, so they developed the dlgv32 application for viewing their DLG (Digital Line Graph) vector data products.
Vector data allows for visually smooth and easy implementation of overlay operations, especially in terms of graphics and shape-driven information like maps, routes and custom fonts, which are more difficult with raster data. Vector data can be displayed as vector graphics used on traditional maps, whereas raster data will appear as an image ...