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GeographyClass 11Introduction To Remote Sensing

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.

Glossary

This section provides definitions of key technical terms used in remote sensing, which are fundamental for understanding the processes and technologies involved. Absorptance is the ratio of radiant energy absorbed by a substance to the energy it receives, while reflectance is the ratio of radiant energy reflected by a substance to the energy it receives. The electromagnetic spectrum is the continuum of electromagnetic radiation (EMR) ranging from high-frequency gamma rays to low-frequency radio waves. A band refers to a specific wavelength interval within this spectrum. Digital images are arrays of digital numbers (DN) arranged in rows and columns, where each DN represents the intensity value of a pixel. Digital image processing involves numerical manipulation of these DN values to extract information about surface phenomena. False Colour Composite (FCC) images are artificially generated images where colors are assigned to wavelengths different from their natural colors to enhance interpretation. Gray scale is a calibration medium ranging from black to white with intermediate gray values. Sensors are devices that receive EMR and convert it into signals for image formation. The scene is the ground area covered by an image or photograph. Understanding these terms is crucial for grasping the concepts and techniques discussed in remote sensing.

📊 Diagram: No specific diagrams in this section, but the glossary terms relate to figures in later sections showing spectral bands and image types.

🔗 Connection: Prepares the reader for the detailed explanation of the stages involved in 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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