Terminology. Remote Sensing

Absorptance : The ratio of the radiant energy absorbed by a substance to the energy

it receives.

Band : The specific wavelength interval in the electromagnetic spectrum.

Digital image : An array of digital numbers (DN) arranged in rows and columns,

having the property of an intensity value and their locations.

Digital Number : An intensity value of a pixel in a digital image.

Digital Image Processing : The numerical manipulation of DN values for the purpose

of extracting information about the phenomena of the surface they represent.

Electromagnetic Radiation (EMR) : The Energy propagated through a space or a

medium at a speed of light.

Electromagnetic Spectrum : The continuum of EMR that ranges from short wave

high frequency cosmic radiations to long wavelength low frequency radio waves.

False Colour Composite (FCC) : An artificially generated colour image in which

blue, green and red colours are assigned to the wavelength regions to which they do

not belong in nature. For example, in standard a False Colour Composite blue is

assigned to green radiations (0.5 to 0.6 µm), green is assigned to red radiations (0.6

to 0.7 µm and red is assigned to Near Infrared radiation (0.7 to 0.8 µm).

Gray scale : A medium to calibrate the variations in the brightness of an image that

ranges from black to white with intermediate grey values.

Image : The permanent record of a scene comprising of natural and man-made

features and activities, produced by photographic and non–photographic means.

Scene : The ground area covered by an image or a photograph.

Sensor : Any imaging or non–imaging device that receives EMR and converts it into

a signal that can be recorded and displayed as photographic or digital image.

Reflectance : The ratio of the radiant energy reflected by a substance to the energy

it receives.

Spectral Band : The range of the wavelengths in the continuous spectrum such as

the green band ranges from 0.5 to .6 µ and the range of NIR band 0.7 to 1.1 µ.

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Disaster Management

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Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

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Natural Disasters

A natural disaster is a catastrophic event caused by natural processes of the Earth that results in significant loss of life, property, and environmental resources. It occurs when a hazard (potentially damaging physical event) interacts with a vulnerable population and leads to disruption of normal life . Key terms: Hazard → A potential natural event (e.g., cyclone, earthquake). Disaster → When the hazard causes widespread damage due to vulnerability. Risk → Probability of harmful consequences from interaction of hazard and vulnerability. Vulnerability → Degree to which a community or system is exposed and unable to cope with the hazard. Resilience → Ability of a system or society to recover from the disaster impact. 👉 Example: An earthquake in an uninhabited desert is a hazard , but not a disaster unless people or infrastructure are affected. Types Natural disasters can be classified into geophysical, hydrological, meteorological, clim...

geostationary and sun-synchronous

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