MISSION

The U.S. Geological Survey's Topographic Division conducts the National Mapping Program, which produces maps and cartographic data delineating the physical features of land areas in the United States, in its territories and possessions, and in Antarctica. Under the National Mapping Program, the U.S. Geological Survey's Topographic Division assesses Federal and State requirements, sets priorities, and provides needed map products and cartographic services. Through its National Cartographic Information Center network, the Division also collects, catalogs, and distributes a wide variety of cartographic data produced by many Federal, State, local, and private organizations. Included are photographs and space images, maps and charts, geodetic data, and cartographic information in digital form. In addition, the Topographic Division provides technical assistance in the use of cartographic products and information to many public agencies.

ORGANIZATION

The Topographic Division is headquartered at the Geological Survey's National Center, Reston, Va. The Division staff consists of two offices, one for Research and Technical Standards and a second for Plans and Program Development. Mapping activities are carried out by four mapping centers, the Eastern Mapping Center, Reston, Va., the Mid-Continent Mapping Center, Rolla, Mo., the Rocky Mountain Mapping Center, Denver, Colo., and the Western Mapping Center, Menlo Park, Calif. A fifth, the Special Mapping Center, also in Reston, is scheduled for consolidation with the Eastern Mapping Center in early fiscal year 1980.

MAJOR ACTIVITIES

The National Mapping Program encompasses the following major activities:

Quadrangle mapping and revision, which involves the production and revision of 7.5-minute maps at 1:24,000 scale in Inch-Pound System units and 1:25,000 scale in metric units for the conterminous United States, Hawaii, and developing areas in Alaska, and maps at 1:63,360 scale (Inch-Pound System units) and 1:50,000 scale (metric units) for Alaska.

• Digital mapping, a recent addition to the National Mapping Program involving the preparation of digital cartographic data in standard formats suitable for computer analysis and the provision of services to other Federal agencies for digitizing, editing, analyzing, and displaying digital cartographic data.

• Small-scale and special mapping, including preparation of maps and map products from the intermediate-scale (1:50,000 and 1:100,000) series to the small-scale U.S. base maps (1:2,500,000).

• The National Cartographic Information Center (NCIC), which acquires and disseminates information about the Nation's maps, charts, aerial and space photographs, geodetic control, digital cartographic information, and other related cartographic data. Research, development, and modernization of mapping to improve the quality of standard map products; to provide new products, such as digital cartographic data that make maps and map-related information more useful to people; to reduce costs and increase productivity of Government mapping activities; to acquire innovative and more useful equipment and to design and to develop new techniques and systems; and to build and to test components for an advanced airborne system designed to speed surveying important areas of the Nation.

BUDGET AND PERSONNEL

For fiscal year 1979, National Mapping Program obligations amounted to almost $74.57 million, an increase of 8.94 percent over fiscal year 1978. Included are funds from 40 States, which, when matched by Federal funds, amounted to over $6.7 million for cooperative mapping. The cooperative projects mutually benefit the State and national program by ensuring completion of map coverage sooner than would otherwise be possible. The National Mapping Program of the Geological Survey is carried out through a combination of in-house efforts and contracts. The in-house effort involves about 1,551 career employees, many with special training in cartography, data processing, engineering, photographic technology, and the physical sciences. About 249 additional employees, many on work-study programs, serve as temporary aids.

Direct program ---

Reimbursable program

National Cartographic

Information Center

Direct programs

Reimbursable Cartographic

Center

Direct $3.02

National

Information

Public and private organizations involved in land and resource planning and management are making increased use of computer-based analyses. These agencies require cartographic data in formats that are directly usable in their computer systems.

At the same time, advanced mapping systems use digital instruments to record and computers to process and to store information as streams of digital codes from which maps subsequently can be produced. The Geological Survey has undertaken a program to exploit these advanced production systems in response to specific identified requirements. This digital data service will be able to collect, to process, to store, and to distribute cartographic and geographic data in digital formats. Categories of cartographic data being digitized include line graphics, land nets, boundaries, transportation, hydrography, culture, and elevations.

DIGITAL TECHNOLOGY DEVELOPMENT

Geological Survey cartographers are taking advantage of computer technology to enhance many production procedures. With the modern digital cartographic equipment, it is possible to reorganize many phases of map production to allow greater flexibility in mapping techniques and products.

Digital data can be derived directly from stereoaerial photographs (stereomodels). Interactive editing and cartographic machine-plotting techniques are used for production of conventional map color separates. Data collected from the stereomodels can be used not only for producing final map separates, but also for establishing digital topographic data bases for map revision and data dissemination. The process involves online acquisition, formatting, filtering, and interactive editing of the topographic map data. The edited data can be plotted in final scribe copy, along with enhancements needed to produce color-separated bases.

Many interactive editing functions, such as line clipping, line extending, and stereomodel joining, can be performed on the digital map data. Internal editing can include any separateto-separate feature for correlation needed for color composite register, such as registering contour reentrants with drains, offsetting buildings from roads to avoid conflict of symbology, and registering multifeature intersections. Other types of data editing include line smoothing, feature redigitizing, and placement of names and other text. The amount of editing required for each separate depends upon the amount of map detail that is required for the final scribing process. Many of the separates, such as transportation, drainage, and culture, require little smoothing of the data and are interactively edited to essentially a finished manuscript. In contrast, the contour separate requires so much interactive editing that it must be processed differently. The contour data are first edited to remove gross blunders and then machine scribed on a Mylar manuscript that is returned to the compiler for a final manual edit.

Edited Mylar plots can be generated by a digital map production system and given to a final scriber for touchup without the need of the initial map compiler rescribing. Plots of edited digitized separates have shown that content and register were identical for all color separates except the contour sheets. It was found also that, as a result of the interactive data acquisition process, a digital representation of the cartographic features in a 7.5-minute quadrangle can be stored on a magnetic tape or disk for future processing in map revision, data structuring, and map database construction.

The cost of digital interactive compilation over manual scribing has not been established. Research is continuing to evaluate these aspects and to establish and to develop a digital data base that will provide additional products and greater flexibility.

TRANSFORMATION

SYSTEM

The Geological Survey is evaluating a multiple microcomputer data processor to transform sets of digital cartographic data from one map coordinate system to another. Currently, time-consuming transformation programs are run on expensive mainframe computers.

Preliminary design of the Coordinate Transformation System has been completed as a high-speed direct-memory-access interconnection scheme between a front-end processor minicomputer and remote microcomputer modules. After the network interconnect details are resolved, hardware will be assembled and performance measured and optimized.

MAP SCANNING AND
DIGITIZING SYSTEM

Digital cartographic data collected during the map compilation may be stored in digital files for later use. However, the Geological Survey has about 35,000 map bases in its files for which the corresponding digital data have yet to be stored.

To produce digital data from these maps, the Geological Survey has designed a map scanning and digitizing system. The new system consists of the following subsystems: (1) raster scanning and editing, (2) raster recording and printing, and (3) data conversion and formatting. Maps measuring up to 36 inches by 36 inches and printed in 10 colors can be scanned and encoded during a single pass, creating digital data sets from standard map products. The interactive raster editing station uses a 19-inch color video tube for color analysis and reassignment, varying lines and fills, and generation of symbols, register marks, numbers, and text. The recorder and printer use a laser to record raster-formatted digital data on positive or negative photographic film.