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| Earth Resources Observation and Science (EROS) |
Glossary U through Z
An arc that does not intersect another arc. See dangling arc.
UNEP was established as a result of the United Nations Conference on the Human Environment convened in Stockholm in 1972, UNEP is dedicated to providing leadership and encouraging partnership in caring for the environment by inspiring, informing and enabling nations and peoples to improve their quality of life without compromising that of future generations.
The UNESCO is based out of Paris, France. UNESCO adopts standard-setting instruments (conventions, recommendations, declarations) in the field of education, science, culture, and communication. These instruments do not deal with products or processes. Recommendations of a semi-technical nature include those copyrights, statistics, and the compatibility of information systems.
Established in March of 1879, the Geological Survey's primary responsibilities are: investigating and assessing the Nation's land, water, energy, and mineral resources; conducting research on global change; investigating natural hazards such as earthquakes, volcanos, landslides, floods, and droughts; and conducting the National Mapping Program. To attain these objectives, the Geological Survey prepares maps and digital and cartographic data; collects and interprets data on energy and mineral resources; conducts nationwide assessments of the quality, quantity, and use of the Nation's water resource; performs fundamental and applied research in the sciences and techniques involved; and publishes and disseminates the results of its investigations in thousands of new maps and reports each year.
UTM is a widely used map projection that employs a series of identical projections around the world in the mid-latitude areas, each spanning six degrees of longitude and oriented to a meridian. This projection is characterized by its conformality; that is, it preserves angular relationships and scale plus it easily allows a rectangular grid to be superimposed on it. Many worldwide topographic and planimetric maps at scales ranging between 1:24,000 and 1:250,000 use this projection.
Any quantity which has both magnitude and direction, as opposed to scaler which has only magnitude.
Vector data, when used in the context of spatial or map information, refers to a format where all map data is stored as points, lines, and areas rather than as an image or continuous tone picture. These vector data have location and attribute information associated with them.
Vertical positional accuracy is based upon the use of USGS source quadrangles which are compiled to meet National Map Accuracy Standards (NMAS). NMAS vertical accuracy requires that at least 90 percent of well defined points tested be within one half contour interval of the correct value. Comparison to the graphic source is used as control to assess digital positional accuracy.
Vertices are the intersecting points of lines. Commonly, in GLIS data sets, these points define either unique locations which represent end points of a line feature, or corners of a polygon or area feature.
The definition of DMA DEMs, as presently stored in the USGS data base, references the WGS 72 datum. WGS 72 is an Earth-centered datum. The WGS 72 datum was the result of an extensive effort extending over approximately three years to collect selected satellite, surface gravity, and astrogeodetic data available throughout 1972. These data were combined using a unified WGS solution (a large-scale least squares adjustment).
The WGS 84 datum was developed as a replacement for WGS 72 by the military mapping community as a result of new and more accurate instrumentation and a more comprehensive control network of ground stations. The newly developed satellite radar altimeter was used to deduce geoid heights from oceanic regions between 70 degrees north and south latitude. Geoid heights were also deduced from ground-based Doppler and ground-based laser satellite-tracking data, as well as surface gravity data. This system is described in "World Geodetic System 1984," DOD DMA TR 8350.2 September 1987. New and more extensive data sets and improved software were used in the development.
Difference (Meters)
Degrees Latitude Longitude Height
90 N 0.0 0.0 4.1
85 0.4 1.5 4.1
80 0.8 3.0 4.0
75 1.3 4.4 3.9
70 1.7 5.9 3.8
65 2.1 7.2 3.6
60 2.4 8.6 3.4
55 2.8 9.8 3.2
50 3.1 11.0 3.0
45 3.4 12.1 2.7
40 3.6 13.1 2.4
35 3.9 14.0 2.0
30 4.1 14.8 1.7
25 4.2 15.5 1.3
20 4.4 16.1 1.0
15 4.4 16.5 0.6
10 4.5 16.5 0.2
5 N 4.5 17.1 -0.2
0 4.5 17.1 -0.6
5 S 4.4 17.1 -1.0
10 4.4 16.9 -1.4
15 4.2 16.5 -1.8
20 4.1 16.1 -2.1
25 3.9 15.5 -2.5
30 3.7 14.8 -2.8
35 3.5 14.0 -3.1
40 3.3 13.1 -3.4
45 3.0 12.1 -3.7
50 2.7 11.0 -3.9
55 4.2 9.8 -4.2
60 2.1 8.6 -4.3
65 1.7 7.2 -4.5
70 1.4 5.9 -4.7
75 1.1 4.4 -4.8
80 0.7 3.0 -4.8
85 0.4 1.5 -4.9
90 S 0.0 0.0 -4.9
Applies only when proceeding directly from WGS 72 coordinates to WGS 84 coordinates; does not contain the effect of the WGS 84 Earth gravitational model and geoid, nor the effect of local geodetic system-to-WGS 84 datum shifts being better than local geodetic system-to-WGS 72 datum shifts.
The WRS is a global indexing scheme designed for the Landsat program based on nominal scene centers defined by path and row coordinates.
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.
Zenith is the point on the celestial sphere vertically above a given position or observer.
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