Introduction To Remote Sensing | Class 11 Geography Notes
By ConceptScroll Team · Published on 17 July 2026 · 4 min read
Introduction To Remote Sensing – this guide gives you a concise, exam-ready overview of Introduction To Remote Sensing from Class 11 Geography, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
Introduction To Remote Sensing
Remote sensing is the science and art of obtaining information about objects or areas from a distance, typically from aircraft or satellites. Unlike human eyes or photographic systems that respond to a narrow portion of the electromagnetic spectrum, modern remote sensing devices detect a much wider range of radiations that are reflected, emitted, absorbed, or transmitted by objects at temperatures above absolute zero (0 Kelvin or -273°C). The term 'remote sensing' was first introduced in the early 1960s and is defined as the total process of acquiring and measuring information about some property of objects or phenomena by a recording device (sensor) that is not in physical contact with the objects or phenomena under study. This definition highlights three essential components: the object surface, the recording device (sensor), and the energy waves carrying the information. The energy waves can be natural, such as sunlight, or artificially generated, such as radar beams. Figure 6.1 in the textbook illustrates this conceptual framework, showing the natural sensor (human eye or instruments), the energy waves, and the object surface. Remote sensing thus enables the study of Earth's surface features and phenomena without direct contact, making it invaluable for geographic, environmental, and resource management applications.
📊 Diagram: Figure 6.1 shows the conceptual framework of remote sensing with three main components: the natural sensor (human eye or instruments), the information-carrying energy waves (electromagnetic radiation), and the object surface that reflects, absorbs, or emits energy.
🔗 Connection: Leads to understanding the glossary of key terms used in remote sensing, which is essential before exploring the stages of remote sensing data acquisition.
Frequently asked questions
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
(i) Correct order of evolution is BCA. Explanation: Initially, human eyes (B) were used for observation, followed by photographic systems (C), and then remote sensors (A) were developed for remote sensing.
(ii) X-rays (c) are not used in satellite remote sensing. Explanation: Satellite remote sensing commonly uses microwave, infrared, and visible regions of the electromagnetic spectrum. X-rays are not used due to their high energy and absorption by the atmosphere.
(iii) Digital image processin
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.
(i) Remote sensing is better because it allows data collection over large areas quickly and repeatedly without physical contact, enabling monitoring of inaccessible or hazardous regions.
(ii) IRS (Indian Remote Sensing) satellites are primarily used for earth observation and resource management, whereas INSAT (Indian National Satellite System) satellites are mainly for communication, broadcasting, and meteorological services.
(iii) A pushbroom scanner uses a linear array of detectors to scan t
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.6.9).
(i) A whiskbroom scanner uses a rotating mirror to scan the ground across the satellite's flight path. It collects data point by point or line by line by sweeping the detector's field of view across the swath. The detector receives reflected radiation from the ground as the mirror oscillates. This method allows high spatial resolution but involves moving parts.
Difference from pushbroom scanner: Pushbroom scanners use a linear array of detectors that simultaneously capture an entire line of dat
ACTIVITY Identify various features marked on IRS IC LISS III imagery shown below. Draw clues from the description of the elements of image interpretation discussed and the colours in which various objects appear on a Standard False Colour Composite.
To identify features on IRS IC LISS III imagery:
- Use knowledge of image interpretation elements such as tone, texture, pattern, shape, size, shadow, and association.
- Recognize that in a Standard False Colour Composite, vegetation appears red due to near-infrared reflectance.
- Water bodies appear dark or black.
- Urban areas appear in shades of cyan or blue.
- Agricultural fields show distinct patterns and textures.
- Use these clues to label features such as forests, water bodies, urban set
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