European Facility For Airborne Research

European Facility For Airborne Research June 29, 2022, 00:04

Terms - S

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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.


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