The process of gathering information using sensors mounted on artificial satellites is known as satellite remote sensing. Different types of scanners capable of recognizing specific areas in the electromagnetic spectrum are mounted on artificial satellites. These scanners recognise different objects on the basis of spectral signatures and transmit that information digitally to ground stations. These are analysed with the help of computers and transformed into images. These are known as satellite imageries.

Spectral signature Sensors record electromagnetic radiations that are reflected or emitted by objects. Each object on the earth’s surface reflects electromagnetic radiation differently. This difference in the amount of reflection is because of the variations in the physical properties of objects. The amount of reflected energy by each object is called the spectral signature of that object.

Spatial resolution 

Sensors fixed on satellite cannot recognize objects of all sizes on the earth’s surface. Sensors with low spatial resolution can only distinguish big objects on the earth’s surface. Eg: Land, sea, hills, forests, etc. The recently developed high spatial resolution sensors can distinguish houses, vehicles, trees, etc. Spatial resolution of a sensor is the size of the smallest object on the earth’s surface that it can recognize.

Sensors

Instruments used for data collection through remote sensing are called sensors. Camera and scanners are sensors. Sensors work with the help of electromagnetic radiations. Sensors record electromagnetic radiations that are reflected or emitted by objects.