Earth Imaging Glossary
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MEAN EARTH-SUN DISTANCE
Mean Earth-Sun distance is the arithmetical mean of the maximum and minimum distances
between a planet (Earth) and the object about which it revolves (Sun).
NAD27--North American Datum of 1927
NAD27 is defined with an initial point at Meads Ranch, Kansas, and by the parameters of the
Clarke 1866 ellipsoid. The location of features on USGS topographic maps, including the
definition of 7.5-minute quadrangle corners, are referenced to the NAD27.
NAD83--North American Datum of 1983
NAD83 is an Earth-centered datum and uses the Geodetic Reference System 1980 (GRS 80)
ellipsoid, unlike NAD27, which is based on an initial point (Meades Ranch, Kansas). Using
recent measurements with modern geodetic, gravimetric, astrodynamic, and astronomic
instruments, the GRS 80 ellipsoid has been defined as a best fit to the worldwide geoid.
Because the NAD83 surface deviates from the NAD27 surface, the position of a point based
on the two reference datums will be different.
NADIR
Point on the ground vertically beneath the center of a remote sensing platform.
NAPP--National Aerial Photography Program
NAPP was established to coordinate the collection of aerial photography covering the 48
contiguous States and Hawaii every five years. NAPP's goals are to ensure that photography
with uniform scale, quality, and cloud-free coverage be made available to meet the
requirements of several Federal and State agencies. The program was initiated in 1980 as the
National High Altitude Photography (NHAP) program. In 1987, the program was renamed to
NAPP when the flying height for the program changed from 40,000 feet to 20,000 feet.
NAPP photography is available in black and white, and in most cases, color-infrared. The
program is administered by the U.S. Geological Survey's National Mapping Division. NAPP
imagery is used by the USGS for photo revision and land use land cover characterization
work on the standard series maps at 1:24,000; 1:100,000 and 1:250,000 scales.
For further information, contact: ASCS Aerial Photography Field Office
Customer Services, EROS Data Center
Earth Science Information Centers (ESICs)
NASA--National Aeronautics and Space Administration
The NASA was formed during the administration of President Dwight D. Eisenhower as a
response by the President and the United States Congress to achievements in space by the
then Union of Soviet Socialist Republics (USSR) including Sputnik I and II. Emphasis was
placed on consolidating projects, facilities, and personnel into a national program including
the National Advisory Committee for Aeronautics (NACA) which would later become the
nucleus for the NASA. The NASA researches solutions to flight problems within and outside
of the Earth's atmosphere. The NASA also develops, constructs, tests, and operates
aeronautical and space vehicles. These vehicles, both manned and unmanned, are part of the
NASA's research activities in the exploration of space. In addition, the NASA coordinates the
scientific and engineering resources of the United States with other nations engaged in
aeronautical and space activities for peaceful purposes.
NASA/ARC--National Aeronautics and Space Administration/Ames Research Center
The ARC's two installations are located at Moffett Field, California, and at the Dryden Flight
Research Facility in Edwards, California. The ARC is responsible for managing a diverse
series of research and technology development programs in support of NASA activities
including flight simulation and research; aerospace and human factors; atmospheric and
Earth sciences applications; and space biology and medicine. The ARC also is responsible
for maintaining research and test facilities and equipment including wind tunnels, simulators,
supercomputers, and aircraft.
NASA/JSC--National Aeronautics and Space Administration/Johnson Space Center
NASA/JSC or JSC supports the acquisition of Earth observations photography by training the
astronauts in Earth science and providing real-time mission support to make the crew aware
of photo opportunities during the flight (i.e, hurricanes, fires, floods, volcanoes, ice flows,
etc.). JSC also trains the crew to use the camera systems and the techniques needed to acquire
high quality photography of Earth and environmental phenomena. After each mission JSC
catalogs the acquired photography and enters new records into the Space Shuttle Earth
Observation Program (SSEOP) data base. This data base is accessible from GLIS through the
use of the REMOTE MENU option.
For further information, contact: Media Services Branch, Still Photography Library
NASA Johnson Space Center
NATIONAL ATLAS
The National Atlas of the United States of America is a bound collection of full-color maps
and charts showing physical features such as landforms, geology, soil, vegetation, and
climate. It is produced by the U.S. Geological Survey's Topographic Division in cooperation
with other Federal agencies and private organizations. Economic, social, and cultural
information is also presented. All maps of the United States contained in the National Atlas
are based on the Albers equal area projection.
NATIONAL GEODETIC VERTICAL DATUM OF 1929
Reference surface established by the U.S. Coast and Geodetic Survey in 1929 as the datum to
which relief features and elevation data are referenced in the conterminous United States;
formerly called "mean sea level 1929."
NATIONAL MAP ACCURACY STANDARDS
Specifications promulgated by the U.S. Office of Management and Budget to govern
accuracy of topographic and other maps produced by Federal agencies.
NATSGO--National Soil Geographic
The NATSGO data base is used primarily for national and regional resource appraisal,
planning, and monitoring. The boundaries of the Major Land Resource Areas (MLRA) and
regions were used to form the NATSGO data base.
NATURAL GAMMA
This is a technique of examining the total gamma radiation of rocks in a drill hole.
NCAR--National Center for Atmospheric Research
The NCAR, based out of Boulder, Colorado, performs research related to atmospheric
problems. NCAR provides service to the university research community and conducts
research toward achieving a better understanding of the overall behavior of the atmosphere,
including analyzing and predicting atmospheric behavior, establishing solar terrestrial
connections, understanding air chemistry and climate, evaluating environmental and societal
effects, and studying connective storms and severe weather.
For further information, contact: National Center for Atmospheric Research
NCDS--NASA Climate Data System
The NCDS is an interactive scientific information management system that allows
researchers to locate, access, manipulate, and display a wide variety of climate data. This
data can be analyzed on the NCDS host computer or downloaded to other computers for
additional analysis. The NCDS library includes many data sets from NASA satellites and
various conventional data base sources. This system is located at the Goddard Space Flight
Center in Greenbelt, Maryland.
For further information, contact: NASA Climate Data System
NCSS--National Cooperative Soil Survey
The NCSS is a joint effort of the United States Department of Agriculture and agencies of the
States, usually the Agriculture Experiment Stations. In some surveys, other Federal and local
agencies also contribute. The Natural Resources Conservation Service (NRCS) has
leadership for the Federal part of the NCSS.
NDCDB--National Digital Cartographic Data Base
The NDCDB is a collection of the digital cartographic/geographic data files produced by the
U.S. Geological Survey (USGS) as part of the National Mapping Division (NMD). The
NDCDB contains elevation data, planemetric data, and landuse and landcover data in various
map scales. The digital data are useful for the production of cartographic products such as
plotting base maps and for various kinds of spatial analysis. A major use of these digital
cartographic/geographic data is to combine them with other geographically referenced data,
enabling scientists to conduct automated analyses in support of various decision making
processes.
NDVI--Normalized Difference Vegetation Index
The NDVI is computed by calculating the ratio of the VI (vegetation index, i.e., the
difference between Channel 2 and 1) and the sum of Channels 2 and 1. Thus NDVI =
(channel 2 - channel 1) / (channel 2 + channel 1).
NEATLINES
Neatlines separate the body of a map from the map margin. On quadrangle maps, the
neatlines are often the meridians and parallels that delimit the quadrangle.
NESDIS--National Environmental Satellite, Data and Information Service
NESDIS is the element in NOAA that is responsible for establishing a digital archive of data
collected from the current generation of NOAA operational polar orbiting satellites.
NGDC--National Geophysical Data Center
The NGDC at Boulder, Colorado, was created in 1965. It is one of three data and information
centers of NOAA's National Environmental Satellite, Data and Information Service
(NESDIS). NGDC brings together in one data center activities in solar-terrestrial physics,
marine geology/geophysics, and solid earth geophysics.
For further information, contact: National Geophysical Data Center
NIMA--National Imagery Mapping Agency
Activities formerly part of Combat Support Center (see DMA).
NIMBUS
The Nimbus satellite program, initiated by the National Aeronautics and Space
Administration (NASA) and later operated by both NASA and the National and Oceanic
Atmospheric Administration (NOAA), was developed in the early 1960s to meet research
and development needs of the atmospheric and Earth scientists, providing global surveillance
of the atmospheric structure at low Earth orbital altitudes for the world's weather services.
NN--Nearest Neighbor Resampling
When correcting image data points, the nearest neighbor technique assigns for each new
pixel that pixel value which is closest in relative location to the newly computed pixel
location.
NOAA--National Oceanic and Atmospheric Administration
The NOAA, under the Department of Commerce, operates the civil polar-orbiting and geo-
stationary satellite systems for the collection of atmospheric and environmental data.
NPS--National Park Service, Department of the Interior
In 1916, Congress enacted the establishment of the NPS to provide unified administration of
parks and monuments. The NPS manages a diverse system of entities including parks,
monuments, historic sites, battlefields, seashores, lakeshores, and recreation areas. The NPS
also directs programs to assist other Federal agencies, State and local governments, and
individuals in the protection of architectural, archeological, historical, and natural resources
that are not part of the National Park System.
NRCS--Natural Resources Conservation Service
The U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS)
provides leadership and administers programs to help people conserve, improve, and sustain
natural resources and the environment. NRCS' work covers three major areas: soil and water
conservation, natural resource surveys, and community resource protection and management.
Prior to 1995, NRCS was known as the SCS (Soil Conservation Service).
NSDI--National Spatial Data Infrastructure
Executive Order 12906, "Coordinating Geographic Data Acquisition and Access: The
National Spatial Data Infrastructure," was signed on April 11, 1994, by President William
Clinton. Under this order, each Federal agency is to document all new geospatial data it
collects or produces, either directly or indirectly, using the standard developed by the Federal
Geographic Data Committee (FGDC) and make that documentation electronically accessible
to the Clearinghouse network.
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