Question

Explain the various components of remote sensing

Answer 1

COMPONENTS OF REMOTE SENSING
Though the methods for collection, processing, and interpretation of remotely sensed data are
very diverse, imaging systems have the following essential components (Panigrahy and Ray,
2006):
1.1 Energy Source or Illumination
The first requirement for remote sensing is to have an energy source, which illuminates or
provides electromagnetic energy to the target of interest. Sensors can be classified as passive
or active, based on the energy source they are using. Sensors, which sense natural radiations,
either emitted or reflected from the Earth, are called passive sensors. Most of the remote
sensing sensors are passive in nature, which measure the solar radiation reflected from the
target. On the other hand, the sensors which produce their own electromagnetic radiation, are
called active sensors (e.g. LIDAR, RADAR).
1.2 Interaction with the Target
As the energy travels from its source to the target, it will come in contact with and interact
with the atmosphere it passes through. This interaction may take place a second time as the
energy travels from the target to the sensor. Once the energy makes its way to the target
through the atmosphere, it interacts with the target depending on the properties of both the
target and the radiation. A number of interactions are possible when Electromagnetic energy
encountersmatter, whether solid, liquid or gas.
 Radiation may be transmitted, that is, passed through the substance.
 Radiation may be absorbed by a substance and give up its energy largely toheating the
substance.
 Radiation may be emitted by a substance as a function of its structure and
temperature. All matter at temperatures above absolute zero, 0°K, emits energy.
 Radiation may be scattered, that is, deflected in all directions and lost ultimately to
absorption or further scattering (as light is scattered in the atmosphere).
 Radiation may be reflected.
1.3 Recording of Energy by the Sensor
After the energy has been scattered by, or emitted from the target, we require a sensor
(mounted on a satellite orbiting in space) to collect and record the electromagnetic radiation.
The sensors are popularly known by the EMR region they sense. Remote sensing can be
broadly classified as optical and microwave (Navalgund et al, 2007). In optical remote
sensing, sensors detect solar radiation in the visible, near-, middle- and thermal-infrared
wavelength regions, reflected/scattered or emitted from the earth (Table 1). On the other
hand, when the sensors work in the region of electromagnetic waves with frequencies
between 109
and1012 Hz, it is called microwave remote sensing. This is highly useful, as it
provides observation of the earth’s surface, regardless of day/night and the atmospheric
conditions. The Radar is an active microwave remote sensing system, which illuminates the
terrain with electromagnetic energy, detects the scattered energy returning from the terrain
(called radar return) and then records it as an image. Intensity of radar return, for both aircraft
and satellite-based systems, depends upon radar system properties and terrain properties.


1.4 Transmission, Reception, and Processing
The energy recorded by the sensor has to be transmitted, often in electronic form, to a
receiving and processing station at earth where the data are processed and stored in digital
form.
1.5 Interpretation and Analysis
The processed data is interpreted, visually and/or digitally to extract information about the
target which was illuminated. Specialized instruments/hardware and software are used for
this purpose that are commonly known as image processing tools. The final element of the
remote sensing process is achieved when we apply the extracted information in solving a
particular problem. Specialists working in each application field/theme generally are able to
carry out this task.
Image processing, also called digital image processing as it handles digital data, involves four
basic steps.

Answer 2

The various components of remote sensing are:

Explanation:

1. Energy source: It is also known as the illuminator. It is used as a source of energy.

2. Radiation: It is the form in which the energy is transmitted from the source

3. Interaction with the target: The energy strikes the source

4. Recording of the energy: The energy is recorded and transferred

5. Transmission, reception, and processing: The energy is transmitted to the destination, there it is processed and sent.

6. Interpretation: The data collected is analysed  

7. Application: The known data is applied.