FUTURE OUTLOOK

AUTOMATION

Maps and charts are based on a framework of ground-survey control points. The cost of providing the framework and producing the maps is increas

ing at the same time that the demand for maps rises. The Federal Government is solving this problem by automating as many surveying and mapping operations as are practical.

Field surveying is being augmented by new computer techniques for photogrammetric control ex

tension (aerotriangulation). Satellites also are being used to extend control to regions where none has been established. These developments and other electronic advances have contributed greatly to automating procedures for acquiring and processing ground survey data.

Hydrographic chart production is also being automated. Water depths and ship positions are being recorded in automated format. Along with digitized land features, data are being processed by computer and will be eventually plotted by machine.

Topographic surveys are a different problem because the basic map data are still generally interpreted by an operator. Some work is now being done by semiautomated stereoplotting machines under operator control. Development of automatic scanning and correlating devices may eventually remove the major burden of interpretation from the operator, allowing him to monitor the machine operation and intervene when necessary.

Remote-sensing techniques to inventory and manage the Nation's resources and monitor the environment show great promise. For example, because if its synoptic coverage, Landsat imagery has permitted identification of previously unmapped geologic structures as targets for exploration for oil, gas, copper, and other minerals, and is being used to inventory water impoundment areas.

The repetitive coverage of satellite data provides information for land use planning with a timeliness not previously possible. The capability of detecting changes in land and water use has proved effective in monitoring strip mines and reclaiming workedout areas. The coverage will be useful in identify. ing beach erosion and gaging the environmental impact of projects, such as construction of the Alaskan pipeline.

Satellite-collected data, in addition to that of Landsat, include the monitoring capability of Skylab and other spacecraft, such as weather satellites. In the cartographic field these data may be used to identify and locate new features, such as interstate highways, and to monitor the spread of urban areas. Revision of small-scale maps from data obtained by satellite remote sensing is already a reality. For example, the maps of the Amazon Basin were revised after space imagery resolved misconceptions concerning the drainage pattern.

The technique of satellite geodesy has proved to be extremely valuable in remote parts of the world. Tracking systems can produce ground accuracies of ±1.5 m. Geodetic positions are derived from processing radio signals transmitted by special satellites.

The satellite signals are received by a sophisticated ground receiver and processed by computer. This surveying method will be used more in the future.

Computer-stored Data

When cartographic information is stored in digital form, the data can be retrieved and processed later by automatic means. The primary advantage of the digital form is the capability of automatic access. It is important to provide the most efficient and flexible storage system possible.

Digital map data fall into three basic categories— point data, line data, and area data. Point data include such features as control stations, boundary monuments, and wells. They are recorded by coordinates and include any feature that can be located by a point. An expansion of the point concept leads to line data, which line data, which include roads, railroads, and streams. Linear features constitute sequences of closely spaced point coordinates. Area data are those that require a tint or pattern, such as woodland, swamp, and urban areas. Although the boundaries of areas can be defined by lines, use of a pixel (picture element) array simplifies the task of digitiz ing area data.

In general, the larger the amount of stored data, the greater are the accuracy and flexibility in selective retrieval; however, an attempt to record an overabundance of data may result in both storage problems and high costs. Compacting the digital information and developing a less costly storage system should be considered.

Data directly available in digital form can be input to a map data bank with relative ease. However, most of the data would come from line drawings and published maps. Automatic line-following devices are being developed for digitizing drawings. Similar scanning devices for area data and techniques for digitizing map data during compilation are also being studied.

Computer-stored cartographic data can be retrieved automatically either as a printout or as a line drawing, depending upon whether statistical data or a graphical analysis is desired.

The statistics derived from a single data base may vary according to the judgment of the statisticians. Because the original source data are retained, a digital map allows each user to judge for himself without the influence of prejudices inevitably imposed on a printed map by its compilers. Because the basic data are somewhat permanent, the user is free to make his own interpretation.

Updating

Often a map or chart is out of date before it is published because of the time needed for the many steps of compilation and publication. However, a computerized map or chart can be corrected regularly. Erroneous or obsolete information can be changed by inserting a correction instruction; actual additions or deletions to copy are unnecessary. The initial task of digitizing published maps and charts is monumental, but digital maps and charts of the future will be produced and revised more easily.

For detailed information about research and current methods in automated cartography, refer to the journals and information services of the technical sources listed in appendix 4.

THE METRIC SYSTEM

Adoption of the metric system in the United States is having a marked effect on mapping procedures. For the most part, cartographers will deal with metric units of length. Fortunately, the ground control used in mapping is generally extended from the National Geodetic Network, which has always been based on the meter. Many of the electronic distance-measuring devices used for horizontal control measurements read out in meters. Vertical control by leveling has been measured in either feet or meters, depending on the equipment used -the trend is toward the use of metric rods and compatible instruments. Where elevations have already been obtained in feet, conversion to meters is simple. However, rewriting station descriptions. that are referenced to feet, yards, and miles would be a monumental task.

Manufacturers of photogrammetric instruments usually design their products in the metric system. Most stereocompilation instruments provide for direct elevation readout in either system. With instruments whose elevation readout is in the U.S. customary system, metrication is being effected by a minor change in equipment.

Because of the conversion to the metric system, changes in format, scale, contour intervals and drafting specifications are necessary. To facilitate metric scaling there may be greater use of even publication scales such as 1:20,000 and 1:100,000. The scales of previously published maps may be changed photomechanically with a minimum of cartographic work. Scale changes may require format changes to reduce sheet size; for example, a series with a 7.5-min quadrangle format could be replaced by one with a metric grid format. Drafting specifica

tions for symbol size and line weight usually are stated as fractions of an inch; they can easily be rewritten in millimeters. However, some tools may have to be modified to accomodate this change.

Probably the greatest problem of metric conversion will be changing contour intervals. Commonly used intervals of 5, 10, 20, 40, and 80 ft will be replaced by intervals of 1, 2, 5, 10, and 20 m. Thousands of contour manuscripts must be redrawn when intervals become metric.

Federal plans include complete conversion to metric products as soon as practical. All new series will be metric when feasible. Series that are nearly finished probably will be completed in the U.S. customary system, but revisions will be metricated.

THE FUTURE

No doubt there will be significant changes in the techniques of surveying and mapping during the next few decades. M.M. Thompson (1974) discusses changes in methods that have taken place in the last quarter century, the current procedures and equipment that are likely to be replaced by new systems, and a projected state of the art in surveying and mapping for the year 2000. Predictions of the shape of surveying techniques in the years to come can be based on advanced systems already under development.

SELECTED REFERENCES

Technical references are too numerous to be included in this list. Some of the publications are used frequently by USGS and NOAA to establish policies or to provide mapping and charting specifications. The rest contain information and data of general interest and value.

American Congress on Surveying and Mapping and the American Society of Civil Engineers, 1972, Definitions of surveying and associated terms: Washington, 205 p. American Society of Photogrammetry, 1966, Manual of photogrammetry, Morris M. Thompson, Editor-in-Chief: Falls Church, Va., v. 1 and 2, 1,199 p.

1968, Manual of color aerial photography, John T. Smith, Editor-in-Chief: Falls Church, Va., 550 p.

1975, Manual of remote sensing, Robert G. Reeves, Editor-in-Chief: Falls Church, Va., v. 1 and 2, 2,144 p. Anderson, J. R., 1971, Land use classification schemes and the need for standardization: Proceedings of the Conference on Land Use Information and Classification, June 28-30, 1971, Washington, U.S. Department of the Interior, Geological Survey, and the National Aeronautics and Space Administration, p. 4-25.

1971, Land use classification schemes used in selected recent geographic applications of remote sensing: Photogrammetric Engineering, v. 37, no. 4, p. 379-387.

Anderson, J. R., Hardy, E. E., Roach, J. T., and Whitmer,

R. E., 1976, A land use and land cover classification system for use with remote sensor data: U.S. Geol. Survey Prof. Paper 964, 28 p., 4 figs., 4 tables. Anderson, R. R., 1972, Applications of high-altitude remote sensing to coastal zone ecological studies: Proceedings of Seminar on Operational Remote Sensing, American Society of Photogrammetry, p. 191-195. Anderson, R.R., and Wobber, F. J., 1973, Wetlands mapping in New Jersey: Photogrammetric Engineering, v. 39, no. 4, p. 353-358.

Bartlett, D. S., Daiber, F. C., and Klemas, V., 1973, Mapping
Delaware's coastal vegetation and land use from aircraft
and satellites: Proceedings of the Fall Convention,
American Society of Photogrammetry, p. 926-937.
Bouchard, Harry, 1965, Surveying, revised by F. H. Moffitt:
Scranton, Pa., International Textbook Co., 754 p.
Clawson, Marion, 1972, America's land and its uses: Balti-
more, Resources for the Future, by The Johns Hopkins
Press, 166 p.

Clawson, Marion, and Stewart, C. L., 1965, Land use in-
formation: A critical survey of U.S. statistics including
possibilities for greater uniformity: Baltimore, Resources
for the Future, by The Johns Hopkins Press, 102 p.
Cravat, H. R., and Glaser, Raymond, 1971, Color aerial
stereograms of selected coastal areas of the United
States: NOAA/National Ocean Survey, 93 p.
Csati, Erno, ed., 1974, Automation and new trends in car-
tography, Final report on the CIA Commission III
(Automation in Cartography) Scientific Working Ses-
sion, August 1973: Budapest, The Geocartographic Re-
search Department, Institute of Surveying and Mapping,
372 p.

Davis, R. E., Foote, F. S., and Kelly, J. W., 1966, Surveying theory and practice: New York, McGraw-Hill. Defense Mapping Agency Topographic Center, 1973, Glossary of mapping, charting, and geodetic terms: Washington, Department of Defense, 281 p.

Dietz, C. H., and Adams, O. S., 1944, Elements of map projection: U.S. Coast and Geodetic Survey Spec. Pub. 68, 200 p. Grimes, B. H., and Hubbard, J. C. E., 1971, A comparison of film type and the importance of season for interpretation of coastal marshland vegetation: Photogrammetric Record, v. 7, no. 38, p. 213–222. Klemas, V., Bartlett, D., and Rogers, R., 1975, Coastal zone

classification from satellite imagery: Photogrammetric Engineering and Remote Sensing, v. 41, no. 4, p. 499–513. Maloney, F. E., and Ausness, R. C., 1974, The use and legal significance of the mean high water line in coastal boundary mapping: North Carolina Law Review, v. 53, no. 2, p. 185-273.

McEwen, R. B., Kosco, W. J., and Carter, V. P., 1976, Coastal wetland mapping: Photogrammetric Engineering and Remote Sensing, v. 42, no. 2, p. 221-232. Melcher, Daniel, and Larick, Nancy, 1966, Printing and Promotion Handbook: New York, McGraw-Hill, 451 p. Mitchell, H. C., 1948, Definitions of terms used in geodetic and other surveys: U.S. Coast and Geodetic Survey Spec. Pub. 242, 87 p.

Moffitt, F. H., 1967, Photogrammetry: Scranton, Pa., 2nd edition, International Textbook Co., 540 p.

NOAA/National Ocean Survey, 1974, Classification, stand

ards of accuracy and general specifications of geodetic control surveys: Rockville, Md., 12 p.

1975, Specifications to support classification, standards of accuracy, and general specifications of geodetic control surveys: Rockville, Md., 30 p.

Photogrammetric instructions: NOAA/NOS, Rockville, Md. (issued irregularly).

Nunnally, N. R., and Whitmer, R. E., 1970, Remote sensing for land-use studies: Photogrammetric Engineering, v. 36, no. 5, p. 449–453.

O'Hargan, P. T., 1973, Wetland boundaries: Proceedings of the Fall Convention, American Congress on Surveying and Mapping, p. 179-185.

Raisz, Erwin, 1962, Principles of cartography: New York, McGraw-Hill, 315 p.

Reimold, R. J., Gallagher, J. L., and Thompson, D. E., 1973, Remote sensing of tidal marsh: Photogrammetric Engineering, v. 39, no. 5, p. 477-488. Robinson, A. H., and Sale, R. D., 1969, Elements of cartography: New York, John Wiley and Sons, 415 p. Rosenberg, Paul, Erikson, K. E., and Rowe, G. C., 1974, Digital mapping glossary: Prepared by Keuffel and Esser Company, Morristown, New Jersey, for the U.S. Army Engineer Topographic Laboratories, U.S. Army Mobility Equipment Research and Development Center, Fort Belvoir, Va., 62 p.

Shalowitz, A. L., 1962, Shore and sea boundaries: Washington, U.S. Government Printing Office, v. 1, 420 p.

1964, Shore and sea boundaries: Washington, U.S. Government Printing Office, v. 2, 749 p.

Shaw, S. P. and Fredine, C. G., 1971, Wetlands of the United States: U.S. Fish and Wildlife Service, Circ. 39, 67 p. Schureman, Paul, and Hicks, S. D., 1975, Tide and current glossary: Rockville, Md., NOAA/National Ocean Survey, 25 p.

Strahler, A. N., 1969, Physical geography: New York, John Wiley and Sons, Third ed., 733 p.

Swanson, R. L., 1974, Variability of tidal datums and accuracy in determining datums from short series of observation: NOAA Tech. Rept. NOS 64, 41 p. Thompson, D. E., 1972, Airborne remote sensing of Georgia tidal marshes: Proceedings of Seminar on Operational Remote Sensing, American Society of Photogrammetry, p. 126-139.

Thompson, Morris M., 1972, Water Features on Topographic Maps: Journal of the Surveying and Mapping Division, ASCE, v. 98, no. SU 1, p. 1-16.

1974, Surveying and mapping in the year 2000: Proceedings of the ASP/ACSM Fall 1975 Technical Meeting, Phoenix, Ariz., p. 362–368.

Umbach, M. J., 1960, Hydrographic manual: NOAA/National Ocean Survey: Rockville, Md., 283 p.

U.S. Geological Survey, Topographic Instructions of the United States Geological Survey: Reston, Va. (issued irregularly).

U.S. Urban Renewal Administration, Housing and Home Finance Agency, and Bureau of Public Roads, 1965, Standard land use coding manual, a standard system for identifying and coding land use activities: Washington, D.C., 111 p.

Weidel, J. W., and Kleckner, Richard, 1974, Using remote sensor data for land use mapping and inventory: A user guide: U.S. Geol. Survey Interagency Rept., USGS-253, 63 p.