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photogrammetric plotters are producing digital maps instead of pencil 
manuscripts; graphical maps are then produced by line plotters under 
computer control. Editing by interactive computer graphics is being 
developed. Some agencies are experimenting with interpretation of 
satellite imagery for land use determination and with airborne sensors 
for soil and geologic data. Increased use of photointerpretation has 
increased the demand for color photographs. Many cartographers are 
finding color photography superior for mapping, especially in arid 
regions and for pavement surfaces. 
The field which has shown the highest rate of growth is photo- 
logging. Typically, a 35 millimeter camera, mounted in a van, takes a 
photograph through the windshield every 52.8 feet, that is, 100 photo- 
graphs every mile. The resulting photography may be studied by highway 
specialists to extract many types of information. Individual photographs 
may be projected, or a series may be viewed in rapid succession, to 
inventory signing and traffic control devices, surface and roadside con- 
ditions, lane markings, entrances, encroachments, and many other items. 
They are useful to study high accident sites or sites of individual 
accidents. Some organizations are obtaining dimensions from the photo- 
graphs by applying photogrammetric principles to single photographs or 
to successive pairs of photographs. Today, 40 or more States and some 
cities, counties, and Federal agencies are engaged in photologging 
of primary and secondary highways. 
TOPOGRAPHIC DIVISION, U.S. GEOLOGICAL SURVEY 
Ed Swasey 
Major photogrammetric activities of the U.S. Geological Survey 
include the following items. 
1. In 1973 almost all Washington, D.C. operations were consoli- 
dated in the new USGS National Center at Reston, Virginia. A National 
Cartographic Information Center (NCIC) was established to assemble and 
disseminate comprehensive information on maps, charts, aerial and space 
imagery covering the United States. The EROS Data Center was established 
at Sioux Falls, South Dakota as a national repository for processing and 
distributing aerial and space imagery. 
2. The "Standard Specifications for Aerial Photography for 
Photogrammetric Mapping" were revised and republished in May 1974. The 
new specifications differentiate between aerial photography for standard 
compilation, for fully analytical aerotriangulation, and for orthophotography. 
Annual photocoverage has increased from 415,000 km? in FY 1972 
to 1,215,000 km? in FY 1975. The proportion of high altitude photography 
-53-