European Facility For Airborne Research April 4, 2025, 17:18
saturation: The point at which a system is unable to handle any further input. That is, when the input signal (e.g. the voltage) exceeds the dynamic range of the detector.
scale: The ratio of a distance on an image or map to its corresponding distance on the ground.
scan line: The ground trace of a narrow strip that is recorded by the instantaneous field of view of a detector in a scanner system.
scene: Terrain area covered by an image; several images (in different spectral bands, or different time repetitions) correspond to a single scene .
sensor: Any device that gathers energy and presents it in a form suitable for obtaining information about the environment.
signal-to-noise ratio (SNR): The ratio of level of signal power to the level of noise power disturbing the signal.
signature: see spectral signature.
smile: Smile is the change of dispersion angle with the field position. It results in the bending of the spectral lines (in the hyper spectral image).
spatial data: Any data with a direct or indirect reference to a specific location or geographical area.
spatial resolution: A measure of the ability to separate or distinguish closely spaced spatial objects.
spectral band: Wavelength region of one spectral interval within the spectral coverage of an instrument. Often called spectral channel.
spectral calibration: Laboratory measurements of spectral sensor properties. The measurements are used to calculate the spectral sensor parameters.
spectral channel: see spectral band.
spectral coverage: Wavelength range between the lower wavelength boundary and the upper wavelength boundary measured by an instrument.
spectral resolution: A measure of the ability to resolve features of the electromagnetic spectrum.
spectral response: The response of a material as a function of wavelength to incident electromagnetic energy, particularly in terms of the measurable energy reflected from and emitted by the material.
spectral sampling distance: Distance in wavelength between the spectral band centre wavelengths of neighbouring spectral bands.
spectral signature: The quantitative measurement of the properties of an object at one or several wavelength intervals. That is, the spectral distribution pattern of radiation reflected and/or emitted by an object.
spectrometer: A device used to measure radiant intensity or to determine the wavelengths of various radiations.
solar azimuth: Azimuth angle of the sun. Angle between the line from the observer to the sun projected on the ground and the line from the observer due north in a clockwise direction. (North = 0°, East = 90°)
solar elevation: Elevation angle of the sun. Angle between the direction of the geometric centre of the sun's apparent disk and the horizon. (sunrise = 0°)
solar zenith: Zenith angle of the sun. Angle between the direction of the geometric centre of the sun's apparent disk and the zenith. (sunrise = 90°)
standard: A published document which sets out specifications and procedures designed to ensure that a material, product, method or service is fit for its purpose and consistently performs in the way it was intended.
standard deviation (STD): The square root of the variance. The value is expressed in the units of measure in which the observations were taken.
stray light: Radiation that reaches the detector from outside its iFOV or from within the sensor by reflection or diffusion.
striping: Banding effect caused by the variation of the spectral response of the detectors of a sensor.
survey: Data acquisition over area of interest determined by a user or a data provider.
sun angle: The angle of the Sun above the horizon. Also called Sun elevation and Sun elevation angle.
sunphotometer: A device that measures the properties of light emanating from the sun.
swath: Across track extent of a strip or segment of an airborne or satellite sensor.
SWIR: Shortwave infrared - The preferred term for the longer wavelengths in the infrared region.
system correction: System correction denotes the calibration of the data from raw DN to a physical unit (usually at-sensor radiance) using calibration coefficients derived from laboratory calibration and/or based on on-board calibration sources.