Radiometric calibration is a general term used in science and technology for any set of calibration techniques in support of the measurement of electromagnetic radiation and atomic particle radiation. These can be for instance, in the field of

radiometry Radiometry is a set of techniques for measurement, measuring electromagnetic radiation, including visible light. Radiometric techniques in optics characterize the distribution of the radiation's power (physics), power in space, as opposed to phot ...

or the measurement of ionising radiation radiated from a source.

Ionising radiation

Ionising radiation is non-visible and requires the use of ionisation detectors such as the Geiger Muller counter or ion chamber for its detection and measurement. Instruments are calibrated using standards traceable to national laboratory radiation standards, such as those at The National Physical Laboratory in the UK. Count rate measurements are normally associated with the detection of particles, such as

alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay but may also be produce ...

s and beta particles. However, for

gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

and

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

dose measurements a unit such as the gray or

sievert The sievert (symbol: SvPlease note there are two non-SI units that use the same Sv abbreviation: the sverdrup and svedberg.) is a derived unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizin ...

is normally used. The following table shows ionising radiation quantities in SI and non-SI units.

Satellite sensor calibration

Spectral data acquired by satellite sensors are influenced by a number of factors, such as atmospheric absorption, scattering, sensor-target-illumination geometry, sensor calibration, and image data processing procedures, which tend to change through time. Targets in multi-date scenes are extremely variable and have been nearly impossible to compare in an automated mode. In order to detect genuine landscape changes as revealed by changes in surface reflectance from multi-date satellite images, it is necessary to carry out radiometric correction. Two approaches to radiometric correction are possible: absolute and relative. The absolute approach requires the use of ground measurements at the time of

data acquisition Data acquisition is the process of sampling signals that measure real-world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems, abbreviated by the ...

for

atmospheric correction An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmospher ...

and sensor calibration. This is not only costly but also impractical when archival satellite image data are used for change analysis. The relative approach to radiometric correction, known as relative radiometric normalization (RRN), is preferred because no in-situ atmospheric data at the time of satellite overpasses are required. This method involves normalizing or rectifying the intensities or digital numbers (DN) of multi-date images band-by-band to a reference image selected by the analyst. The normalized images would appear as if they were acquired with the same sensor under similar atmospheric and illumination conditions to those of the reference image.Yang, Xiajun, and C. P. Lo. "Relative radiometric normalization performance for change detection from multi-date satellite images." Photogrammetric Engineering and Remote Sensing 66.8 (2000): 967-980.

References

* Olsen, Doug; Dou, Changyong; Zhang, Xiaodong; Hu, Lianbo; Kim Hojin; Hildum, Edward. 2010.
Radiometric Calibration for AgCam
Remote Sens. 2, no. 2: 464–477. *D. Hall; G. Riggs; V. Salomonson. (1995). "Development of methods for mapping global snow cover using moderate resolution imaging spectroradiometer data." Remote Sensing of Environment. 54, no. 2: 127–140. {{DEFAULTSORT:Radiometric Calibration Remote sensing C

Ionising radiation

Satellite sensor calibration

See also

References