NCERT Book Class 11 Geography Introduction To Remote Sensing

STAGES IN REMOTE SENSING

Figure 7.2 illustrates the processes used in remote sensing data acquisition. These basic processes that help in the collection of information about the properties of the objects and phenomena of the earth surface are as follows :

(a) Source of Energy (sun/self-emission);

(b) Transmission of energy from the source to the surface of the earth;

(c) Interaction of energy with the earth’s surface;

(d) Propagation of reflected/emitted energy through atmosphere;

(e) Detection of the reflected/emitted energy by the sensor;

(f) Conversion of energy received into photographic/digital form of data;

(g) Extraction of the information contents from the data products; and

(h) Conversion of information into Map/Tabular forms.

a. Source of Energy: Sun is the most important source of energy used in remote sensing. The energy may also be artificially generated and used to collect information about the objects and phenomena such as flashguns or energy beams used in radar (radio detection and ranging).

b. Transmission of Energy from the Source to the Surface of the Earth: The energy that emanates from a source propagates between the source and the object surface in the form of the waves of  Introduction To Remote Sensing energy at a speed of light (300,000 km per second). Such energy propagation is called the Electromagnetic Radiation (EMR). The energy waves vary in size and frequency. The plotting of such variations is known as the Electromagnetic Spectrum (Fig. 7.3). On the basis of the size of the waves and frequency, the energy waves are grouped into Gamma, X– rays, Ultraviolet rays, Visible rays, Infrared rays , Microwaves and Radio waves. Each one of these broad regions of spectrum is used in different applications. However, the visible, infrared and microwave regions of energy are used in remote sensing.

EXERCISE

1. Choose the right answer from the four alternatives given below

(i) Remote sensing of objects can be done through various means such as A. remote sensors, B. human eyes and C. photographic system. Which of the following represents the true order of their evolution.

(a) ABC

(b) BCA

(c) CAB

(d) None of the above

(ii) Which of the following regions of Electromagnetic spectrum is not used in satellite remote sensing.

(a) Microwave region

(b) Infrared region

(c) X - rays

(d) Visible region

(iii) Which of the following is not used in visual interpretation technique ?

(a) Spatial arrangements of objects

(b) Frequency of tonal change on the image

(c) Location of objects with respect to other objects

(d) Digital image processing

2. Answer the following questions in about 30 words.

(i) Why is remote sensing a better technique than other traditional methods?

(ii) Differentiate between IRS and INSAT series of satellites.

(iii) Describe in brief the functioning of pushbroom scanner.

3. Answer the following questions in about 125 words.

(i) Describe the operation of a whiskbroom scanner with the help of a diagram. Explain how it is different from pushbroom scanner.

(ii) Identify and list the changes that can be observed in the vegetation of Himalayas (Fig.7.9).

Please refer to attached file for NCERT Class 11 Geography To Remote Sensing