- 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.
That property of an object which is dependent on the wavelength of the light it reflects or, in the case of a luminescent body, the wavelength of the light it emits. If, in either case, this light is of a single wavelength, the color seen is a pure spectral color, but, if the light of two or more wavelengths is emitted, the color will be mixed. White light is a balanced mixture of all the visible spectral colors.
Industry:Aerospace
The ability of an imaging system to distinguish closely spaced objects in the subject area. Can be expressed as the spacing, in line-pairs per unit distance, of the most closely spaced lines that can be distinguished. See instantaneous field of view and resolution cell.
Industry:Aerospace
The ability to see large areas at one time, such as an entire metropolitan area.
Industry:Aerospace
The adjustment or systematic standardization of the output of a quantitative measuring instrument or sensor.
Industry:Aerospace
The angle between the heading of the axis of a craft and its ground track.
Industry:Aerospace
The angle of the Sun above the horizon. Both the quantity (lumens) and the spectral quality of light being reflected to a remote sensor are influenced by Sun angle. Also called Sun elevation and Sun elevation angle.
Industry:Aerospace
The angular orientation of a spacecraft as determined by the relationship between its axes and some reference line or plane or some fixed system of axes. Usually, "y" is used for the axis that defines the direction of flight, "x" for the "cross-track" axis, perpendicular to the direction of flight, and "z" for the vertical axis. Roll is the deviation from the vertical (the angle between the z-axis of the vehicle and the vertical axis, or angular rotation around the y-axis). Pitch is the angular rotation around the x-axis. Yaw is rotation around the z-axis.
Industry:Aerospace
The apparent change in the position of one object, or point, with respect to another, when viewed from different angles.
Industry:Aerospace
The arc of the horizon measured clockwise from the north point to the point referenced. Expressed in degrees. Azimuth indicates direction, and not location.
Industry:Aerospace
The attempt to trace radiometric units and calibrations back to a common radiance source at the United States National Institute of Standards and Technology (NIST) in order to compare measurements taken by different methodologies in absolute terms. The stability and precision requirements for remote sensing from space are often higher than that of (1) the transfer calibration from NIST to transfer lamps, (2) the calibrated radiometers for vicarious measurements and (3) the calibrated on-board sources. For this reason, some sensors reference their calibration to presumably more quantifiable and more stable solar irradiance rather than to NIST-traceable pre-launch calibration of on-board calibrators. However, in the absence of any absolute national radiance standard other than at NIST, it is still necessary to reference radiometric calibrations to NIST standards. Also see radiometric reflective band calibration.
Industry:Aerospace
