A 125 Year History of Topographic Mapping and GIS
in the U.S. Geological Survey 1884-2009, Part 2
E. Lynn Usery, Dalia Varanka, Michael P. Finn
U.S. Geological Survey
Center of Excellence for Geospatial Information Science
1400 Independence Road
The United States Geological Survey (USGS) entered the mainstream of developments in computer-assisted technology for mapping during the 1970s. The introduction by the USGS of Digital Line Graphs (DLGs), Digital Elevation Models (DEMs), and the Land Use Data Analysis (LUDA) nationwide land-cover data provided a base for the rapid expansion of the use of geographic information systems (GIS) in the 1980s.
MOSS & ArcInfo
Whereas the USGS had developed the topologically-structured DLG data and the Geographic Information Retrieval and Analysis System (GIRAS) for land-cover data, the Map Overlay and Statistical System (MOSS), a non-topologically structured GIS software package, developed by Autometric, Inc. under contract to the Fish and Wildlife Service, dominated the use of GIS by Federal agencies in the 1970s. Thus, USGS data were 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 ArcInfo in 1982 changed that and by the end of the 1980s, topological structure for vector data was essential and ArcInfo was the dominant GIS software package used by Federal agencies.
First Map Series for Computer Era
USGS production of the first map series designed specifically for the computer era began in the mid-1970s. The 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, the USGS converted transportation and hydrography from the 1:100,000-scale maps to DLG data.
Conversion into DLG Data
The conversion process required photographic transfer of the transportation and hydrography linework 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 were automatically processed to thin the raster lines to single pixel widths, convert them to vector lines, and build topologic 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 topologic structure construction were complete, the data were transferred to the Census Bureau for additional attribution and entry as a 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, Birch Tree, Missouri, in 1983. During the 1980s, the USGS continued its innovative role with developments in DEM and orthophoto production capabilities.
From 1974 to 1983, the 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 of the lidar systems of today.
Introduction of DOQ
In 1987, the USGS introduced the concept of the digital orthophotograph (DOQ), using digital scanning of photographic stereo pairs and processing software to create a digital image with correct map geometry. Following the introduction, the USGS, in cooperation with the United States Department of Agriculture (USDA), generated digital orthophotos at 1-meter resolution for the 48 contiguous states of the United States. The DOQ of the USGS became the standard base image for many geographic information systems in the 1990s. The 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.
Data Models & SDTS
The 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 Standards Organization in the 1990s. SDTS libraries supporting import and export of data to and from SDTS were developed and made available to the public by the USGS. Many GIS vendors incorporated these libraries into their code packages.
DLG-E & DLG-F
Simultaneous to development of SDTS, the 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 (2009) 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 the USGS became standard in the GIS industry.
U.S. Map Coverages
In 1991, the USGS completed the analog map coverage of the 48 contiguous states of the United States at the 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, the 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, the 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, the 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 multi-resolution seamless, nationwide mosaic of elevations created from existing USGS databases of 7.5-minute tiles with 30 m horizontal spacing, 7-meter root mean square error (RMSE), 1-degree tiles with 3-arc-second horizontal spacing, and a vertical RMSE of 30-meter. The 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.
Introduction of NHD
The USGS also began to construct the 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, the 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.
Seamless Land Cover Data
The National Land Cover Dataset was created as a seamless mosaic of 21 land-cover categories, from Landsat Thematic Mapper (TM) images from 1991-1992. 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.
The National Map
In 2001, the 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; developed and maintained through partnerships; a national foundation for science, land and resource management, recreation, policy making, and homeland security; available over the Internet; and the source for revised topographic maps. The National Map, a collaborative effort to improve and deliver topographic information for the nation, 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 added.
Digital Map–Beta & US Topo
In 2009, the 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 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 US Topo. The remaining layers of The National Map will be added to US Topo in 2011. The NAIP photography acquires complete coverage of the 48-contiguous states every three years, thus the USGS will generate new topographic maps every three years to follow the NAIP cycle.
In surveying, photogrammetry, and cartography, USGS innovations led or enhanced developments in the broader fields of mapping and GIS. The 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.