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| Earth Resources Observation and Science (EROS) |
Glossary E though G
An 8-bit character encoding scheme used primarily on IBM machines.
An ecologic system composed of interacting organisms and their environments. The result of interaction between biological, geochemical and geophysical systems.
EDAC, also known as the Technology Applications Center (TAC), has served as a NASA center since 1964. EDAC operates under the objective of transferring Earth-observing technologies to the user community. It supports and works directly with industries developing technologies related to space science and collaborating with them to enhance and encourage the user community to adopt the new technologies. EDAC also supports and works with public agencies, private citizens, educational organizations, and volunteer groups to ensure ready accessibility to NASA generated space imagery.
EDC is a national archive, production, distribution, and research facility for remotely sensed data and other geographic information. See also EROS.
EIPS is software that calculates the maximum number of image lines that can be consolidated into a tape record.
Electromagnetic radiation is energy propagated through space between electric and magnetic fields. The electromagnetic spectrum is the extent of that energy ranging from cosmic rays, gamma rays, X-rays to ultraviolet, visible and infrared radiation including microwave energy.
This destructive analytical technique is used to determine concentrations of specific chemical elements based on their emission or absorption of specific wavelengths of electromagnetic radiation.
The U.S. Government transferred commercial sales rights of the Landsat program to the private sector on September 27, 1985, authorizing a contract with the Space Imaging. The Landsat program involves satellite remote sensing of the Earth's resources and the dissemination of that data to users worldwide.
Space Imaging is a joint venture/partnership formed by Hughes Aircraft Company and RCA Corporation.
Established on December 2, 1970, the EPA is charged with protecting and enhancing the environment for present and future generations to the fullest extent possible under Congressional law with responsibilities including the control of solid waste, pesticides, radiation, and toxic substances, and the abatement of air and water pollution. The EPA coordinates research and antipollution activities with State and local governments, educational institutions, private and public groups, and individuals.
A table of predicted satellite orbital locations for specific time intervals. The ephemeris data help to characterize the conditions under which remotely sensed data are collected and are commonly used to correct the sensor data prior to analysis.
The EROS program was established in the early 1970s, under the Department of the Interior's U.S. Geological Survey, to receive, process, and distribute data from United States Landsat satellite sensors and from airborne mapping cameras. See also EDC.
The U.S. Geological Survey (USGS) operates a network of ESICs designated to distribute USGS earth science data and related products. There are more than 75 ESIC offices throughout the United States. Major offices are managed by the USGS, but numerous affiliate offices are managed by various State and Federal agencies.
ESIC address information and other ESIC information is available through the ESIC Home Page.
Headquartered in Redlands, California, ESRI provides Geographic Information System (GIS) software, products, and services.
EXPORT creates an ARC/INFO interchange file to transfer coverages, INFO data files, text files, and other ARC/INFO files between various computer systems. An interchange file contains all coverage information and appropriate INFO file information in a fixed length, ASCII format. It can be fully or partially compressed as well as uncompressed ASCII depending upon the given EXPORT option.
To infer (values of a variable in an unobserved interval) from values within an already observed interval.
The FAO is based out of Rome, Italy, to monitor, conduct research, and promote good practices in the area of food and agriculture throughout the world.
The FGDC provides Federal leadership in the evolution of the National Spatial Data Infrastructure (NSDI) in cooperation with State and local governments, academia, and the private sector. The FGDC was established through the U.S. Office of Management and Budget (OMB) Circular A-16 and charged with the responsibility to coordinate various surveying, mapping, and spatial data activities of Federal agencies to meet the needs of the United States. Major objectives of Circular A-16 are to avoid duplication and minimize costs in mapping and spatial data activities, which involves establishing standards and providing wider access to geospatial data. The FGDC also has been charged with coordinating geospatial data related activities with other levels of government and other sectors.
A set of four marks located in the corners or edge-centered, or both, of a photographic image. These marks are exposed within the camera onto the original film and are used to define the frame of reference for spatial measurements on aerial photographs. Opposite fiducial marks connected, intersect at approximately the image center of the aerial photograph.
Photographic products for use in image interpretation are commonly generated from the following film types:
The U.S. National Institute of Standards and Technology (NIST) is responsible for developing standards, guidelines, and associated methods and techniques for computer systems, including those needed to assure the cost-effective security and privacy of sensitive information in U.S. Federal computer systems. NIST adopts and publicizes U.S. FIPS standards under the provisions of Section 111(d) of the U.S. Federal Property and Administrative Services Act of 1949 as amended by the Computer Security Act of 1987.
This non-destructive analytical technique is used to determine concentrations of specific chemical elements. The procedure is based on the artificially induced absorption, atomic excitation, and emission of electromagnetic radiation at characteristic wavelengths.
FORTRAN is a computer programming language. This mathematically oriented language primarily is intended for scientific data processing.
GAC data are derived from a sample averaging of the full resolution AVHRR data. Four out of every five samples along the scan line are used to compute one average value and the data from only every third scan line are processed, yielding 1.1 km by 4 km resolution at the subpoint.
Gain coefficient is a measurement to denote an increase in signal power in transmission from one point to another.
This is a unit of magnetic intensity.
Gamma-ray data are high frequency, penetrating radiation emitted from the nucleus of a radioactive atom.
This non-destructive analytical technique is used to determine concentrations of specific chemical elements such as potassium, thorium, and uranium. These elements have naturally occuring radioactive isotopes based on their normal radioactive decay and the associated emission of gamma-rays at specific wavelengths.
The Gauss-Seidel method is a technique for interpolating irregularly spaced data points, such as spot elevations, onto a regular grid (e.g., Digital Elevation Models). Unlike simple interpolation methods which assume only correlation, the Gauss-Seidel method is used when some characteristics of the system are known, such as the local value of a derivative. This method, which must be solved iteratively, takes the form of an implicit equation.
The Successive Over Relaxation (SOR) method, a refinement to the Gauss-Seidel method, causes the system to converge more rapidly so fewer iterations are required to achieve the same result.
GCPs are physical points on the ground whose positions are known with respect to some horizontal coordinate system and/or vertical datum. When mutually identifiable on the ground and on a map or photographic image, ground control points can be used to establish the exact spatial position and orientation of the image to the ground. Ground control points may be either horizontal control points, vertical control points, or both.
The official U.S. Geological Survey (USGS) map projection software library, the GCTP is a system of software routines designed to permit the transformation of coordinate pairs from one map projection to another. The GCTP is the standard computer software used by the National Mapping Division for map projection computations.
Of or determined by geodesy; that part of applied mathematics which deals with the determination of the magnitude and figure either of the whole Earth or of a large portion of its surface. Also refers to the exact location points on the Earth's surface.
The accuracy with which geographic position and elevation of features on the Earth's surface are mapped. This accuracy incorporates information in which the size and shape of the Earth has been taken into account.
An image that has been geographically referenced or rectified to an Earth model, usually to a map projection. Sometimes referred to as geocoded or geometric registration.
GIRAS reflects the judgement of the USGS concerning the presentation and format of polygonal data. The GIRAS data structure was designed to handle large quantities of data for a map area. With the data structure, the basic topological elements (arcs, nodes, and polygons) are all uniquely identified and cross-referenced to one another.
A system, usually computer based, for the input, storage, retrieval, analysis and display of interpreted geographic data. The data base is typically composed of map-like spatial representations, often called coverages or layers. These layers may involve a three-dimensional matrix of time, location, and attribute or activity. A GIS may include digital line graph (DLG) data, digital elevation models (DEM), geographic names, land-use characterizations, land ownership, land cover, registered satellite and/or aerial photography along with any other associated or derived geographic data.
Based out of New York, New York, GISS, one of NASA's Goddard Space Flight Center research facilities, institutes activities involving research and analysis in specialized subjects, including climate, biogeochemical cycles, remote sensing, and planetary atmospheres.
The Master Directory (MD) is an online computer-based system designed to enable rapid identification and location of data of interest to earth and space science researchers. It provides brief, high level data set information from which the user should be able to identify data of potential interest. The Master Directory has remote linking capabilities to a number of other online data directories.
The MD resides on a VAX at the National Space Science Data Center (NSSDC) and may be reached from GLIS by selecting the Remote Option (6) on the GLIS Main Menu screen.
GMT is the mean solar time of the meridian of Greenwich used as the prime basis of standard time throughout the world.
The GPS is a worldwide satellite navigation system that is funded and supervised by the U.S. Department of Defense. GPS satellites transmit specially coded signals. These signals are processed by a GPS receiver that computes extremely accurate measurements, including 3-dimensional position, velocity, and time on a continuous basis. [Woods Hole Field Center]
GRASS is a product of the U.S. Army Corps of Engineers Construction Engineering Research Laboratories (USACERL) in Champaign, Illinois. It is an integrated set of programs designed to provide digitizing, image processing, map production, and geographic information system capabilities to its users.
DISCLAIMER: Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Relating to weight measurement. A GRAVIMETER is an instrument used for determining the specific gravity of bodies, solid or liquid.
The NASA GSFC was established in 1959 just northeast of Washington, D.C. Goddard's mission is to expand knowledge of the Earth, its environment, the solar system and the universe through the development and use of near-Earth orbiting spacecraft. The GSFC is responsible for supporting NASA's leadership role in space and Earth sciences; research and application of technology for sensors, instruments and information systems; planning and executing space flight projects for scientific research; and for tracking of manned and unmanned Earth satellites through worldwide ground and space communication systems.
A GLIS guest user is one who has not registered as a fully functional GLIS user. The guest user has full search capabilities and may request that data be ordered, but does not have the capability to save session information or search results, have a GLIS electronic mailbox, or use some of the system's advanced features. A guest may register by selecting the USERINFO option from the MAIN_MENU screen.
NOTE: A registered user who has signed on as a guest cannot switch to a "registered user" status within the same session. The user must exit GLIS and login as a registered user.
The GVI is a specific AVHRR application that uses global area coverage (GAC) data to produce a vegetative index called the normalized difference vegetation index (NDVI). GAC data are processed daily and then composited on a weekly basis to produce a global map portraying vegetation vigor.
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