Remote Sensing
The invention of photography in the 19th century has brought about a drastic change in data collection. The possibility of capturing photographs from higher elevations mounting cameras on balloons and air crafts has been explored ever since. Data collection using satellites began in 1960. Along with cameras, different types of scanners were also introduced for data collection. Such a method of collecting information about an object, place or phenomenon without actual physical contact is remote sensing.
Devices used for data collection in remote sensing are called sensors. Cameras and scanners are sensors. The sensors record the electromagnetic radiations reflected by objects.
The carrier on which sensors are fixed is called a platform. Sensors can be installed on balloons, air crafts and satellites. Based on the source of energy and the platform remote sensing can be classified as follows:
Classification of Remote Sensing Based on Source of energy
Remote sensing:-
Passive Remote Sensing
Remote Sensing is carried out with the help of solar energy is known as passive remote sensing. Here the sensors do not emit energy by itself.
Active Remote Sensing
Remote Sensing made with the aid of artificial source of energy radiating from the sensor is known as active remote sensing.
Classification of Remote Sensing based on the platform
Terrestrial Photography
The method of obtaining the earth's topography using cameras from the ground is known as terrestrial photography.
The method of obtaining photographs of the earth's surface continously from the sky by using cameras mounted on aircrafts is known as aerial remote sensing.
The process of gathering information using the sensors installed in artificial satellites is known as satellite remote sensing.