- Branża: Aerospace
- Number of terms: 16933
- Number of blossaries: 2
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The Executive Branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research.
In remote sensing, measurements pertaining to the spectral or geometric characteristics of a sensor or radiation source. Calibration data are obtained through the use of a fixed energy source such as a calibration lamp, a temperature plate, or a geometric test pattern. The application of calibration data to restore measurements to their true values is called rectification.
Industry:Aerospace
In the broadest scene, the measurement or acquisition of information of some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study; for instance, the utilization at a distance (as from aircraft, spacecraft, or ship) of any instrument and its attendant recording and display devices for gathering information pertinent to the environment such as measurements of force fields; electromagnetic radiation, or acoustic energy. The technique employs such devices as cameras, lasers, radio frequency receivers, radar systems, sonar seismographs, gravimeters, magnetometers, multispectral scanners, and scintillation counters.
Industry:Aerospace
Inclination of the terrain from horizontal. It is expressed in convenient units, such, as percent, feet per mile, etc.
Industry:Aerospace
In-orbit radiometric calibration of a satellite sensor by a method independent of that used to perform the initial laboratory calibration. Two methods are commonly used when making vicarious measurements of ground truth: the radiance-based method in which data from the sensor are compared with radiance measured by a sensor mounted on an aircraft, and the reflectance-based method in which a radiative transfer model is used to estimate the top-of-atmosphere radiance from a ground target of known reflectance. Also see ground truth/ground observations, radiance-based calibration and reflectance-based calibration.
Industry:Aerospace
Irregular variation in, or deviation from, what is usual or expected, as in the orbital motion of a satellite being affected by extraordinary pull.
Industry:Aerospace
Lamps carried into orbit on imaging sensors for the purpose of measuring the responsivity of reflective band detectors as a function of time under the assumption that controlling or monitoring the current or spectral radiance of the lamp will result in a constant or known irradiance on the detectors. There were three such lamps on each of the Thematic Mapper (TM) sensors on the Landsat 4/5 satellites that were cycled in an 8-step sequence whenever the instruments were turned on. There were two lamps on the Enhanced Thematic Mapper Plus (ETM+) imager on Landsat 7; the primary one was used on almost every acquisition, while the redundant one was only used a few times per year. Also see detector responsivity, internal calibrator, and radiometric reflective band calibration.
Industry:Aerospace
Level 0 Reformatted Landsat data product. The Level 0R product is reformatted, raw data. Reformatting includes shifting pixels by integer amounts to account for 1) the alternating forward-reverse scanning pattern of the Enhanced Thematic Mapper Plus (ETM+) sensor, 2) the odd-even detector arrangement within each band, and 3) the detector offsets inherent to the focal plan array engineering design. Pixels are neither resampled nor are they geometrically corrected or registered, i.e. the pixels are NOT aligned per scan line.
Industry:Aerospace
The L1G product is radiometrically and geometrically corrected (systematic) to the user-specified parameters including output map projection, image orientation, pixel grid-cell size, and resampling kernel. The correction algorithms model the spacecraft and sensor using data generated by onboard computers during imaging. Sensor, focal plane, and detector alignment information provided by the Image Assessment System (IAS) in the Calibration Parameter File (CPF) is also used to improve the overall geometric fidelity. The resulting product is free from distortions related to the sensor (e.g., jitter, view angle effect), satellite (e.g., attitude deviations from nominal), and Earth (e.g., rotation, curvature). Residual error in the systematic L1G product is less than 250 meters (1 sigma) in flat areas at sea level. The systematic L1G correction process does not employ ground control or relief models to attain absolute geodetic accuracy.
Industry:Aerospace
The Level 1R product is a radiometrically corrected L0R product. This product 1) corrects detector artifacts such as coherent noise, 2) improves cosmetic artifacts such as banding, striping, and dropped lines or pixels, and 3) is calibrated to radiance units, i.e. color corrected, as integer values. Radiometric corrections are not reversible. Pixels are neither resampled nor are they geometrically corrected or registered, i.e. the pixels are NOT aligned per scan line.
Industry:Aerospace
Light that has traveled through a medium without being absorbed or scattered.
Industry:Aerospace
