- Industry: Aerospace
- Number of terms: 16933
- Number of blossaries: 2
- Company Profile:
The Executive Branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research.
A unitless measure of the ratio of outgoing to incoming solar radiation created by converting a radiometrically calibrated image observed from orbit to the apparent reflectance of the planet being observed (assuming the planet is acting as a perfect Lambertian reflector). Conversion to planetary albedo assumes knowledge of the solar irradiance for a specific spectral band, distance from the Sun and solar zenith angle. Also see reflectance and bidirectional reflectance.
Industry:Aerospace
A variation on the basic Mercator map projection based on the dynamics of satellite motion. The movements of the Landsat platform, sensors, and the Earth, expressed as functions of time, are used to calculate which latitudes and longitudes on the Earth correspond to locations in the projection plane. Thus, a continuous projection of the entire area of coverage is obtained. SOM is conformal and nearly totally distortion-free; it was developed by John Parr Snyder. See Universal Transverse Mercator.
Industry:Aerospace
A widely used map projection employing a series of identical projections around the world in the intermediate latitudes, each covering 6° of longitude and oriented to a meridian. The UTM projection is characterized by its property of conformality, meaning that it preserves scale and angular relationships well, and, by the ease with which it allows a useful rectangular grid to be superimposed on it. Extensively used in navigational applications, the UTM has been the most common projection used with Landsat data. It is sometimes called the Gauss-Kruger projection.
Industry:Aerospace
An Earth satellite orbit in which the orbital plane remains at a fixed angle with respect to the Sun, precessing through 360° during the period of a year. Landsat satellites are in near-polar orbit of this type and maintain an orbital altitude such that each pass over a given latitude on the Earth's surface occurs at the same mean Sun time. Compare with geosynchronous.
Industry:Aerospace
An Earth satellite orbit in which the satellite remains in a fixed position over a geographic location on the Earth. This requires that the orbital plane be in the same plane as the equator, and that the satellite's altitude be high enough for the satellite to revolve about the Earth at a speed equal to that of the Earth's rotation. Geosynchronous orbits are common for most communications satellites, such as the Tracking and Data Relay Satellite System.
Industry:Aerospace
An ideal body which, if it existed, would be a perfect absorber and a perfect radiator, absorbing all incident radiation, reflecting none, and emitting radiation at all wavelengths. In remote sensing, the exitance curves of black bodies at various temperatures can be used to model naturally occurring phenomena like solar radiation and terrestrial emittance.
Industry:Aerospace
An image or photograph made by piecing together individual images or photographs covering adjacent areas.
Industry:Aerospace
An image prepared by processing digital multispectral data. For each pixel the value for one band is divided by that of another. The resulting digital values are displayed as an image. The term ratioing refers to the process by which a ratio image is produced. Often used ratios: NDVI, VI.
Industry:Aerospace
An image transformation, usually a one-to-one operator used to lessen noise or enhance certain characteristics of the image. For any particular (x,y) coordinate on the transformed image, the spatial filter assigns a grey shade on the basis of the grey shades of a particular spatial pattern near the coordinates (x,y).
Industry:Aerospace
An imaginary line drawn directly through the optical center of the camera lens to the geometric center of the film. For Landsat ETM+, TM, or MSS imagery, the point in the image where geometric distortion is at a minimum.
Industry:Aerospace
