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| Earth Resources Observation and Science (EROS) |
Glossary C and D
This is the method of examining the diameter of a drill hole to determine the hardness or softness of the individual rocks.
The natural cycle of carbon dioxide to carbohydrates by photosynthesis and its return to the atmosphere by animal metabolism and decomposition.
Pertaining to cartography, the art or practice of making charts or maps.
CCTs are 1/2-inch-wide magnetic tapes. The term is used in reference to both single tapes and tape sets consisting of a single logical volume of data.
CD-ROM is a computer peripheral that employs compact disc technology to store large amounts of data for later retrieval. The capacity of a CD-ROM disk is over 600 megabytes, the equivalent of over 250,000 typewritten pages.
A range of wavelength intervals selected from the electromagnetic spectrum.
A chip is an image subset window and is used in the correlation process.
The science of climates and their phenomena.
A homogeneous group of units which vary "like" one another. "Likeness" is usually determined by the association, similarity, or distance among the measurement patterns associated with the units.
In the LAS environment, concatenate is the overlaying of an input image with one image or a series of images using the lines and samples to calculate the projection coordinates in the creation of a mosaicked image.
Imaginary line on the ground, all points of which are at the same elevation above or below a specified datum.
A matrix containing the expected values derived from the products of the deviations of pairs of random variables from their means. Covariance measures the extent to which two random numbers vary together (i.e., varying at the same rate in the same direction).
CPES is software used to produce and process a single-band (Band 4) Landsat chip.
CPTs are features of known ground location that can be accurately located on imagery.
The part of the Earth's surface that is perennially frozen; the zone of the Earth where ice and frozen ground are formed.
A high order resampling technique in which the brightness value of a pixel in a corrected image is interpolated from the brightness values of the 16 nearest pixels around the location of the corrected pixel.
NOAA's header quality information file.
An arc having the same polygon on both its left and right sides and having at least one node that does not connect to any other arc. See dangling node.
The dangling endpoint of a dangling arc. Often identifies that a polygon does not close properly (e.g., undershoot), that arcs do not connect properly, or that an arc was digitized past its intersection with another arc (e.g., overshoot). In many cases, a dangling node may be acceptable. For example, in a street centerline map, cul-de-sacs are often represented by dangling arcs.
In surveying, a reference system for computing or correlating the results of surveys. There are two principal types of datums: vertical and horizontal. A vertical datum is a level surface to which heights are referred. In the United States, the generally adopted vertical datum for leveling operations is the national geodetic vertical datums of 1929 (differing slightly from mean sea level). The horizontal datum, used as a reference for position, is defined by: the latitude and longitude of an initial point, the direction of a line between this point and a specified second point, and two dimensions which define the spheroid. In the United States, the initial point for the horizontal datum is located at Meades Ranch in Kansas.
A DBMS is software that supports processes germane to organizing, cataloging, locating, storing, retrieving, and maintaining data (i.e., information) in a data base.
The DCRsi rack mount and modular ruggedized systems are one-inch, transverse scan, rotary digital recorders capable of recording and reproducing at any user data rate from 0 to 13.4 Mbytes/seconds (0-107 Mbits/seconds). DCRsi is a user friendly mass storage data peripheral with a total storage capacity of 48 gigabytes.
A DDR is a file containing image information which may include: (1) number of lines, number of samples, number of bands, data type, and the system on which the data was created; (2) corner coordinates of the image and related projection information; (3) the minimum and maximum values for each band of an image; (4) information describing how and when each band of the image was acquired; and (5) miscellaneous information (e.g., the last date and time modifications were made to an image).
This non-destructive analytical technique is used to determine concentrations of specific chemical elements. The procedure is based on artificially induced neutron capture and the radioactive decay constants of unstable radionuclides that are produced.
The U.S. Geological Survey produces five primary types of digital elevation model data. They are:
7.5-minute DEM (30- x 30-m data spacing, cast on Universal Transverse Mercator (UTM) projection or 1- x 1-arc-second data spacing). Provides coverage in 7.5- x 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute map series quadrangle. Coverage: Contiguous United States, Hawaii, and Puerto Rico.
1-degree DEM (3- x 3-arc-second data spacing). Provides coverage in 1- x 1-degree blocks. Two products (three in some regions of Alaska) provide the same coverage as a standard USGS 1-x 2-degree map series quadrangle. The basic elevation model is produced by or for the Defense Mapping Agency (DMA), but is distributed by USGS in the DEM data record format. Coverage: United States.
30-minute DEM (2- x 2-arc-second data spacing). Consists of four 15- x 15-minute DEM blocks. Two 30-minute DEMs provide the same coverage as a standard USGS 30- x 60-minute map series quadrangle. Saleable units will be 30- x 30-minute blocks, that is, four 15- x 15-minute DEMs representing one half of a 1:100,000-scale map. Coverage: Contiguous United States, Hawaii.
15-minute Alaska DEM (2- x 3-arc-second data spacing, latitude by longitude). Provides coverage similar to a 15-minute DEM, except that the longitudinal cell limits vary from 20 minutes at the southernmost latitude of Alaska to 36 minutes at the northern most latitude limits of Alaska. Coverage of one DEM will generally correspond to a 1:63,360-scale quadrangle.
7.5-minute Alaska DEM (1- x 2-arc-second data spacing, latitude by longitude). Provides coverage similar to a 7.5-minute DEM, except that the longitudinal cell limits vary from 10 minutes at the southernmost latitude of Alaska to 18 minutes at the northernmost latitude limits of Alaska.
The process of recovering a signal from a modulated (varied frequency) carrier wave.
Direction satellite is traveling relative to the Equator. A descending node would imply a southbound Equatorial crossing.
The dormant period among grasshopper eggs used to survive long seasonal dry periods.
Digital count is the total number of pixels occurring in an image for each possible data value.
Digitization of graphics typically involves recording the location of each point, line, and polygon on a map, along with their associated labels and attributes.
A DLG is line map information in digital form. The DLG data files include information about planimetric base categories, such as transportation, hydrography, and boundaries.
The USGS digital line graph (DLG-3) optional format, which was designed for data interchange, allows for the creation of a vector polygon data structure. The topological linkages are explicitly encoded for node, area, and line elements. The files are composed of 8-bit ASCII characters organized into fixed logical records of 80 bytes. Bytes 1 - 72 contain the data, bytes 73 - 77 are blank, and bytes 78 - 80 contain a record sequence number. The detailed description of the DLG-3 optional format is described in Digital Line Graphs from 1:2,000,000-Scale Maps, Data Users Guide 3 (1990).
The DMA was established in 1972, when mapping, charting, and geodesy functions of the Defense Community were combined into this joint Department of Defense agency. The mission of the Agency is to: produce and distribute to the Joint Chiefs of Staff, unified and specified commands, military departments, and other department of defense users, timely and uniquely tailored mapping, charting, and geodetic products, services, and training; provide nautical charts and marine navigational data to worldwide merchant marine and private vessel operators; and maintain liaison with civil agencies and other national and international scientific and other organizations engaged in mapping, charting, and geodetic activities.
The above activities were handled by the DMA Combat Support Center until the Center was disbanded in 1995 and responsibilities were transferred to the National Imagery Mapping Agency.
Dodging is a process used to lighten areas of a photographic print during the main exposure so that the areas which need lightening receive less than the regular exposure. This process, which generally provides more image detail and reduces scene contrast, is performed by a skilled technician using their hands or a paddle over the area in need of less exposure.
A system that utilizes a geosynchronous satellite to re-broadcast satellite data received at a central reception and preprocessing center.
The Doppler system is used to correlate total aeromagnetic readings with the position of the aircraft at the instant readings are taken. The information is then used for mapping aeromagnetic data. The Doppler system is self contained in the aircraft and emits a pulsed or continuous microwave which is sent diagonally downward fore and aft. The frequencies are then compared in order to obtain true ground speed. The heading is obtained from a special magnetic compass and is maintained by a directional gyro used as an integrating device. The distance thus determined has a precision better than one part in a thousand, which is sufficient for most geophysical surveys.
DOS commonly refers to the disk operating system originally developed by MicroSoft, Inc. for use on personal computers. This operating system also refers to that operating system which is used on IBM-compatible personal computers.
An algorithm developed by David H. Douglas (University of Ottawa) and Thomas K. Peucker (Simon Fraser University, British Columbia). This formula was designed to reduce the number of points required to represent a digitized line from a map.
Reducing the number of points saves storage space and also allows for generalization of lines that are very complex.
Geographic area or region containing one or more drainage areas that discharge run-off to a single point.
A DTM is a land surface represented in digital form by an elevation grid or lists of three-dimensional coordinates.
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