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| Earth Resources Observation and Science (EROS) |
Glossary P through R
To break down a sequence of letters or numbers into meaningful parts based on their location in the character sequence. For example, the first three numbers in the GLIS access phone number 6055946888 are the area code numbers that identify the phone number as a South Dakota location.
As defined by GLIS, a PC work station is a 80286 or greater AT micro computer running the MS-DOS operating system version 3.0 or higher. The PC should have 640 kilobytes of computer memory and have a VGA 16 color 4 bit graphics board and color monitor. To allow connection with the GLIS server the PC work station should have a Hayes or Hayes compatible modem and some type of PC communication package. The PC should also have at least 1 megabyte of hard disk space for GLIS software and data files.
Optional GLIS PC work station requirements include a mouse, math co-processor, and dot matrix or laser printer.
A permanently frozen layer at variable depth below the surface in frigid regions of a planet (as Earth).
Refers to the rate and timing of natural events, such as the growth cycle of vegetation over a growing. Land cover and vegetation types may often be distinguished from each other by their characteristic spectral/temporal signature, as illustrated by a graph plotting NDVI values against time through a growing season for several agricultural categories. The shape and position of each curve defines that category's phenological characteristics.
The aspect and character of an abstract entity.
An abbreviation of picture element. The minimum size area on the ground detectable by a remote sensing device. The size varies depending on the type of sensor.
Early in the twentieth century, Max Planck recognized the discrete nature of radiant energy exchanges and proposed the quantum theory of electromagnetic radiation. His experiments showed that energy is transferred in short wave trains or bursts in which each burst carries radiant energy, Q, proportional to the frequency, of the wave, so that: Q = hv where h = the universal, or Planck's constant, with a value of 6.625 X 10 to the -34 joule second. (a joule, in physics, is a unit of work equal to 10 million ergs.)
Two dimensional. The measurement of plane surfaces. A map representing only horizontal features. Parts of a map that represent everything except relief.
The PLDS is a data and information management system developed to support land science research activities by archiving, retrieving, and transferring land data. The PLDS program, sponsored by the Communication and Information Systems Office, Land Processes Branch within the Office of Space Science and Applications of NASA, is managed by Goddard Space Flight Center with active participants at Ames Research Center (ARC) and the Jet Propulsion Laboratory (JPL).
The U.S. Public Land Survey System is the most widespread land ownership system in the United States. Roads, fields and political boundaries all reflect the character of a square grid system or more commonly the Township and Range System.
The POES system began in 1960 with the launch of TIROS-1. Later satellites in the Improved TIROS Operational Satellite (ITOS) program were expanded to capture concurrent multiple-channel data on a daily basis. Currently the Advanced TIROS-N satellites (renamed NOAA-6, 7, 8, etc., after launch) offer 4 or 5 channel multispectral daily repetitive global coverage.
Precision is a statistical measurement of repeatability that is usually expressed as a variance or standard deviation, root mean square or RMS, of repeated measurements. These are expressed as x,y coordinates of arcs, label points, and tics in either single or double precision in ARC/INFO.
Single-precision coordinates have up to seven significant digits of precision. This allows for a level of accuracy of approximately 10 meters for a region whose extent is 1,000,000 meters across.
Double-precision coordinates have up to 15 significant digits; this allows for the precision necessary to represent any desired map accuracy at a global scale.
One method of making Digital Elevation Models (DEMs) is commonly referred to as profiling. In this technique a stereo pair of photographs is set up in a photogrammetric instrument and referenced to the ground using ground control points. After this process is completed the instrument automatically moves a computer cursor across the stereo model. As the cursor is being driven across the model, the operator controls the motion of the cursor while a recording device captures the elevation figures. Each swath across the stereo model is called a profile.
Orderly system of lines on a plane representing a corresponding system of imaginary lines on an adopted terrestrial or celestial datum surface. Also, the mathematical concept of such a system. For maps of the Earth, a projection consists of (1) a graticule of lines representing parallels of latitude and meridians of longitude or (2) a grid.
To limit the possible values of (e.g., quantity) to a discrete set of values by quantum mechanical rules (Webster's II, 1994).
Instrument for measuring altitudes or elevations with respect to a reference level, usually mean sea level. A radar altimeter determines the height of an aircraft above the terrain by measuring the time required for an electromagnetic pulse to travel from aircraft to the ground and back again.
A radian is a unit of angular measure equal to the angle subtended at the center of a circle by an arc of length equal to the radius of the circle equal to approximately 57 degrees, 17 minutes, 44.6 seconds.
Measure of the energy radiated by an object. In general, radiance is a function of viewing angle and spectral wavelength and is expressed as energy per solid angle.
A radiometer is a device used for detecting and measuring radiation. These measurements of electromagnetic radiation are referred to as radiometric measurements.
Diagnostic measurements pertaining to the linear electrical performance of the sensor.
A raster image is a matrix of row and column data points whose values represent energy being reflected or emitted from the object being viewed. These values, or pixels, can be viewed on a display monitor as a black and white or color image.
The process of converting vector points, lines, and areas into raster image format.
The RBV system on Landsats 1 and 2 consisted of three television-like cameras aimed to view the same 185 km-by-185 km area as the multispectral scanner (MSS) sensor. The RBV system did not contain film. The images were exposed by a shutter device and stored on a photosensitive surface within each camera. This surface is then scanned in raster form by an internal electron beam to produce a video signal.
The RBV system instantaneously imaged an entire scene, had greater inherent cartographic fidelity than imagery acquired by the Landsat MSS sensor, and contained a reseau grid in the image to facilitate geometric correction of the imagery. This resulted in an array of tick marks that were precisely placed in each image.
The RBV system on Landsat 1 produced only 1690 scenes between July 23 and August 5, 1972, when a tape recording switching problem forced a system shutdown. The RBV system on Landsat 2 was operated primarily for engineering evaluation purposes and only occasional RBV imagery was obtained, primarily for cartographic uses in remote areas.
These images are no longer available.
Reflectance is the fraction of the total radiant flux incident upon a surface that is reflected and that varies according to the wavelength distribution of the incident radiation.
A GLIS user who has established a userkey and completed the USER INFORMATION screen is a registered user. Registering automatically gives the user enhanced GLIS features including the ability to save session information and results from previous searches.
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.
GLIS users who are registered have the following additional options which are not available to the guest.
A way of modeling information in a database by relations between the features. Relations are usually represented as a collection of tables where each table contains the occurrences of a particular feature. Each column of the table corresponds to an attribute and each row is an instance of the feature. For example, two related tables might be created to describe types of transportation networks in a data set. The first table has columns that uniquely identify the transportation feature, and another that contains codes that describe the transportation type (trails, roads, railways, ferries, etc.). A second table, which relates to the first, might contain columns that list the transportation codes used in the first (related) table, and a second column that defines, in further detail, the definition of the code (gravel, asphalt, concrete, etc) and road maintenance schedule for that type of road surface. The benefit of a relational database is that repetitive information is not recorded numerous times in a table, but instead is pointed to in related tables. Also referred to as Relational Database Management Systems (RDBMS).
A remote link is a direct connection to a computer-based system located at another data center. Links are established via wide area networks and are initiated by the GLIS software. Once connection is established, the control of the user's session is passed to that system.
An array of tick marks precisely placed in an image.
Residual anomalies are geophysically defined features that represent the difference between total (actual) and regional (modeled) geophysical fields; i.e. residual field or anomaly.
The RMSE statistic is used to describe accuracy encompassing both random and systematic errors.
The square of the difference between a true test point and an interpolated test point divided by the total number of test points in the arithmetic mean. The square root of this value is the root mean square error.
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