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USGS Topographic Map Revision

The papers on this page were originally prepared for mapping and geographic information system conferences.

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The papers below contain information of historical interest, but are several years old and do not describe current USGS policies and procedures. For information about current mapping programs, see The National Map site. [January, 2003]

The U.S. Geological Survey's Revision Program for 7.5-Minute Topographic Maps   PDF format.  December, 2000.

Abstract: From the mid-1940s through the late 1980s the 1:24,000-scale, 7.5-minute topographic quadrangle was the primary product of the U.S. Geological Survey"s (USGS) National Mapping Program (NMP). This map series includes about 53,000 map sheets for the conterminous United States and is the only uniform map series that covers this area at such a large scale. The 7.5-minute mapping program lasted almost 50 years, from the mid-1940s until the early 1990s. Revision programs that date from the late 1960s have kept the median currentness date of the map series at 1979. There are four main categories of map revision: minor, basic, complete, and single edition. Minor revision is done on maps that have few changes since the last revision; it includes boundary updates and corrections of previously reported errors. Basic revision updates features from digital orthophoto quadrangles (DOQ) and aerial photographs. Complete revision of all layers is seldom performed because of the high cost. Single-edition revisions are done by the U.S. Department of Agriculture Forest Service using procedures similar to basic revision. Contour update is an optional part of basic and single edition revision but is not often done because of the high cost. These revision programs were not designed to do replacement mapping. Most map revision is done from remote and secondary data sources, including the following:

• Geometry is controlled and some feature content interpreted from DOQs.
• Most feature content is interpreted by using stereophotographs from the National Aerial Photography Program.
• Boundary and name information is collected from Federal databases, other maps, and State and local agencies.

During the height of the 7.5-minute mapping program, a large part of the NMP budget was focused on graphic mapping. Because of funding increases in areas outside graphic map production and evolving customer priorities, the NMP today spends more of its data production resources on digital and image products, as well as more money on geographic research, data distribution, and customer assistance. Because of the expense of traditional topographic mapping, the NMP is investigating alternate data sources, procedures, and product designs for graphic maps.

The prototype software discussed in this paper can be downloaded from http://thor-f5.er.usgs.gov/topomaps/rgc.tar.gz. This file includes a user manual in PDF format. The software is implemented in the ERDAS geographic information system, and requires ERDAS Imagine v8.4 or higher.

Abstract: The U.S. Geological Survey (USGS) 7½-minute mapping program began in the mid-1940s. Maps from the early days of the program were made with technologies that were obsolete by 1960. These technologies included field triangulation and longbar aerotriangulation. Recent work has raised the possibility that many of these early maps are not as accurate as previously believed. Many old maps do not match more recent USGS products, particularly digital orthophoto quadrangles (DOQ), to within acceptable tolerances.

A goal of the USGS map revision program is to ensure that revised graphics meet the accuracy specifications for the appropriate map series. The USGS map revision program is not funded for remapping with new field control, but there are other ways to improve the horizontal accuracy of old bases. DOQs are more accurate than older map bases and can therefore be used to improve the accuracy of the map.

Image warping methods can be used to adjust an old map base to newer, more accurate control. This technique is fast and inexpensive compared to obtaining new field control and doing new compilation. A prototype system based on commercial geographic information system image rubber sheeting has greatly improved the accuracy of some maps and improved the consistency of clusters of maps. In the best case tested so far, the root mean square error of 50 test points was reduced from 93 feet to 33 feet, relative to the DOQ.

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