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USGS History, Part 2: From the Dawn of Digital to The National Map
125 Years of Topographic Mapping
By E. Lynn Usery, Dalia Varanka, and Michael P. Finn, U.S. Geological Survey
See Part 1 on the cover page of the Fall 2009 issue of ArcNews.
The United States Geological Survey (USGS) entered the mainstream of developments in computer-assisted technology for mapping during the 1970s. The introduction by USGS of digital line graphs (DLGs), digital elevation models (DEMs), and land use data analysis (LUDA) nationwide land-cover data provided a base for the rapid expansion of the use of GIS in the 1980s. Whereas USGS had developed the topologically structured DLG data and the Geographic Information Retrieval and Analysis System (GIRAS) for land-cover data, the Map Overlay Statistical System (MOSS), a nontopologically structured GIS software package developed by Autometric, Inc., under contract to the U.S. Fish and Wildlife Service, dominated the use of GIS by federal agencies in the 1970s. Thus, USGS data was used in MOSS, but the topological structure, which later became a requirement for GIS vector datasets, was not used in early GIS applications. The introduction of Esri's ARC/INFO in 1982 changed that, and by the end of the 1980s, topological structure for vector data was essential, and ARC/INFO was the dominant GIS software package used by federal agencies.
USGS production of the first map series designed specifically for the computer era began in the mid-1970s. USGS designed completely new symbology with solid continuous lines and colors suited for automatic scanning and reproduction with computer technology for the 1:100,000-scale topographic maps. The entire series, more than 1,800 maps, was completed in the 1970s and 1980s. In preparation for the 1990 Census, USGS converted transportation and hydrography from the 1:100,000-scale maps to DLG data.
The conversion process required photographic transfer of the transportation and hydrography line work from film negatives to special polyester film sheets. The polyester film sheets were then highlighted with specific colors in special inks to identify potential problems in the digital conversion process. The polyester film sheets were then scanned at 1,200 dots per inch on a raster drum scanner from Scitex. The scanned data was automatically processed to thin the raster lines to single pixel widths, convert them to vector lines, and build topological structure. During the vectorizing process, the Scitex editing software was set to automatically find the special inks used to mark potential trouble areas for the vectorizing algorithm. After the vectorizing and topological structure construction were complete, the data was transferred to the Census Bureau for additional attribution and entry as part of the Topologically Integrated Geographic Encoding and Referencing (TIGER) line files for the 1990 Census.
Production automation had begun in the 1970s with the development of the Digital Cartographic Software System (DCASS) for photogrammetric compilation and the Graphic Map Production System (GRAMPS) for cartographic editing, leading to the release of the first digitally produced map in a provisional format—of Birch Tree, Missouri—in 1983. During the 1980s, USGS continued its innovative role with developments in DEM and orthophoto production capabilities. From 1974 to 1983, USGS conducted research on the Aerial Profiling of Terrain System (APTS) for measuring stream-valley cross sections and profiles, older map reliability testing, and producing control for topographic maps. The system consisted of an inertial measuring unit (IMU), a laser tracker, a laser profiler, a video-imaging system, supporting electronics, and a computer. Data generated by the system included the laser returns to generate elevations and the video images. This system was a precursor to the lidar systems of today.
In 1987, USGS introduced the concept of the digital orthophoto quadrangle (DOQ), using digital scanning of photographic stereo pairs and processing software to create a digital image with correct map geometry. Following the introduction, USGS, in cooperation with the U.S. Department of Agriculture (USDA), generated digital orthophotos at one-meter resolution for the 48 contiguous states of the United States. The DOQ of USGS became the standard base image for many geographic information systems in the 1990s. USGS and other federal agencies continue to acquire new DOQ coverage of the United States every few years, building to complete repetitive coverage with the Imagery for the Nation (IFTN) program.
USGS began data model development for computer-assisted cartography and GIS in the 1970s with GIRAS, DLG, and DCASS. The development of the Federal Geographic Exchange Format (FGEF) in the late 1970s was the beginning of standardization of data models and formats for geographic information and led to the establishment of the Spatial Data Transfer Standard (SDTS), which was adopted by the International Organization for Standardization in the 1990s. SDTS libraries supporting import and export of data to and from SDTS were developed and made available to the public by USGS. Many GIS vendors incorporated these libraries into their code packages. Simultaneous to development of SDTS, USGS developed the digital line graph—enhanced (DLG-E), a feature-based GIS data model released in 1990. Further refinements of DLG-E led to DLG—feature (DLG-F) and, finally, to the feature-based data model currently used in the National Hydrography Dataset (NHD). Whereas the DLG-E and DLG-F models were not incorporated directly into software for GIS, during the next 15 years, the feature-based ideas pioneered by USGS became standard in the GIS industry.
In 1991, USGS completed the analog map coverage of the 48 contiguous states of the United States at 1:24,000 scale. The coverage includes more than 55,000 7.5-minute quadrangles. While completing the production of the 7.5-minute series of the National Mapping Program and continuing its revision, USGS also continued its developments of digital databases for cartography and GIS. After the completion of United States coverage with 7.5-minute, 1:24,000-scale topographic maps, USGS contracted to have the most recent editions of the maps converted to digital raster graphics (DRGs). The DRGs were geocoded and became a critical layer in GIS, useful for image rectification, feature extraction, and other applications.
In the 1990s, USGS moved from quadrangle areas, usually constructed from 7.5-minute, 15-minute, 30-minute, or 1-degree areas to seamless nationwide layer-based datasets. The first of these completed was the National Elevation Dataset (NED), a multiresolution, seamless, nationwide mosaic of elevations created from existing USGS databases of 7.5-minute tiles with 30-meter horizontal spacing, 7-meter root mean square error (RMSE), 1-degree tiles with 3-arc-second horizontal spacing, and a vertical 30-meter RMSE. USGS has continued to improve the NED with elevations on a 10-meter horizontal spacing that is now available for the conterminous 48 states and, most recently, with lidar data, generating elevations on a 3-meter horizontal spacing.
USGS also began to construct the National Hydrography Dataset (NHD) in the 1990s. The NHD incorporates the concept of geographic features in the form of reaches of streams and other geographic entities to represent surface water. In association with the Environmental Protection Agency (EPA) and many state organizations, USGS embarked on a new system of data maintenance and update with the NHD using a system of stewardship. This system is now becoming a model for other data maintenance agreements.
The National Land Cover Dataset was created as a seamless mosaic of 21 land-cover categories from Landsat Thematic Mapper (TM) images from 1991 to 1992. This 30-meter resolution dataset was released in 2001; a second coverage for the United States was released in 2008 from 2001 TM images. Seamless land cover for the United States provides a base for many scientific applications and is one of the most frequently downloaded of the USGS datasets.
In 2001, USGS released its vision for the topographic map of the 21st century: The National Map—a seamless, continuously maintained, nationally consistent set of base geographic data. A collaborative effort to improve and deliver topographic information for the nation, The National Map consists of eight data layers: transportation, hydrography, boundaries, structures, geographic names, land cover, elevation, and orthographic images. The goal of The National Map is to become the nation's source for trusted, nationally consistent, integrated, and current topographic information available online for a broad range of uses. The seamless databases constructed in the 1990s and early 2000s became the base data for The National Map, with additional data from federal, state, local, and tribal sources being continually added.
In 2009, USGS defined the graphic output to be generated and distributed from The National Map as a GeoPDF of the eight data layers. The initial release, known as Digital Map—Beta, included an orthographic image based on photography from the National Agricultural Imagery Program (NAIP), transportation data of interstate and U.S. highways from the Census Bureau, geographic names from the Geographic Names Information System, a United States National Grid shown on 1,000-meter grid lines, and the metadata contained in the map border and collar information. Beginning in October 2009, contours and hydrography were added to the new map, which was renamed USTopo. The remaining layers of The National Map will be added to USTopo in 2011. The NAIP photography acquires complete coverage of the 48 contiguous states every three years; thus, USGS will generate new topographic maps every three years to follow the NAIP cycle.
In surveying, photogrammetry, and cartography, USGS innovations have led or enhanced developments in the broader fields of mapping and GIS. USGS developed agreements for local applications and provided data for land and science management needs. This history of accomplishment forms the basis for future innovations for growth of the industry.
About the Authors
E. Lynn Usery is a research geographer and director of the USGS Center of Excellence for Geospatial Information Science (CEGIS). He received a B.S. degree in geography from the University of Alabama and M.A. and Ph.D. degrees in geography from the University of Georgia. He has over 20 years' experience with USGS and has spent 17 years as professor of geography at the University of Wisconsin, Madison, and the University of Georgia.
Dalia Varanka is a research geographer with USGS. She received a B.A. degree from the University of Wisconsin, Green Bay, in regional and urban analysis; an M.A. degree in geography at the University of Illinois, Chicago; and a Ph.D. degree in geography from the University of Wisconsin, Milwaukee.
Michael P. Finn holds a B.S. in geography with a minor in cartography and map technology from Southwest Missouri State University (now Missouri State University) and an M.S. in civil engineering from Virginia Polytechnic Institute & State University. He has worked as a computer and IT specialist and a research cartographer with the USGS for the past 10 years.
For more information, contact E. Lynn Usery, research geographer and director, CEGIS, U.S. Geological Survey (e-mail: firstname.lastname@example.org); Dalia Varanka, research geographer, USGS (e-mail: email@example.com); or Michael P. Finn, research cartographer, USGS (e-mail: firstname.lastname@example.org). Any use of trade names in this article is for descriptive purposes only and does not constitute endorsement by the United States government.
See Part 1 on the cover page of the Fall 2009 issue of ArcNews.