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 measuring electromagnetic radiation, including visible light. Radiometric techniques in optics characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which ch ...

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 A Geiger counter (also known as a Geiger–Müller counter) is an electronic instrument used for detecting and measuring ionizing radiation. It is widely used in applications such as radiation dosimetry, radiological protection, experimental p ...

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 pro ...

s and

beta particle A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β� ...

s. However, for

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...

and

X-ray X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ' ...

dose measurements a unit such as the

gray Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed ...

sievert The sievert (symbol: SvNot be confused with the sverdrup or the svedberg, two non-SI units that sometimes use the same symbol.) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radi ...

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 for atmospheric correction 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