(SEM VI) THEORY EXAMINATION 2024-25 GIS & REMOTE SENSING

BOE066 – GIS & Remote Sensing (B.Tech Sem VI)

Prepared strictly as per your uploaded question paper (both pages) and written in simple, humanized language with proper explanations (not short points).
(Referenced from the uploaded paper) 

BOE066-GIS-REMOTE-SENSING

SECTION A

Attempt all questions in brief (2 × 7 = 14 marks)

(a) What does RS stand for in GIS?

RS stands for Remote Sensing. It refers to the science of collecting information about the Earth’s surface without direct contact, using sensors mounted on satellites or aircraft.

(b) Define electromagnetic spectrum.

The electromagnetic spectrum is the complete range of electromagnetic radiation arranged according to wavelength or frequency. It includes gamma rays, X-rays, ultraviolet, visible light, infrared, and microwave regions, which are used in remote sensing.

(c) Mention any one major atmospheric window.

One major atmospheric window is the visible region (0.4–0.7 µm), where solar radiation passes through the atmosphere with minimal absorption and scattering.

(d) What is the significance of spectral signature in remote sensing?

A spectral signature is the unique pattern of reflectance or absorption of an object across different wavelengths. It helps in identifying and differentiating features such as vegetation, water, soil, and urban areas in satellite images.

(e) Define contrast ratio in remote sensing.

Contrast ratio is the difference in brightness between two adjacent areas in an image. Higher contrast makes features more distinguishable, improving visual interpretation and classification accuracy.

(f) What is meant by stereoscopic vision?

Stereoscopic vision is the ability to perceive depth by viewing two overlapping images of the same area taken from slightly different angles. It is commonly used in aerial photographs for terrain height and relief analysis.

(g) Write full form of GIS.

GIS stands for Geographic Information System.

SECTION B

Attempt any three (7 × 3 = 21 marks)

(a) Advantages and limitations of remote sensing.

Remote sensing provides large-area coverage, repetitive data collection, and access to inaccessible regions. It supports environmental monitoring, disaster management, and resource mapping.
However, it is limited by atmospheric effects, high cost of data and sensors, requirement of skilled interpretation, and difficulty in capturing subsurface information.

(b) Typical spectral reflectance curve for water.

Water strongly absorbs energy in the infrared and microwave regions and shows low reflectance overall. In the visible region, reflectance is slightly higher in the blue and green wavelengths, which is why clear water bodies often appear blue or green in satellite images.

(c) Whiskbroom and push-broom scanners.

A whiskbroom scanner uses a rotating mirror to scan the Earth surface line by line perpendicular to the satellite path. Examples include Landsat MSS.
A push-broom scanner uses a linear array of detectors that capture an entire line at once as the satellite moves forward. Examples include IRS LISS and Sentinel sensors. Push-broom scanners provide higher radiometric resolution and fewer moving parts.

(d) Basic spatial entities in GIS.

The basic spatial entities in GIS are points, lines, and polygons. Points represent locations such as wells, lines represent features like roads and rivers, and polygons represent areas such as land parcels or lakes.

(e) Concept of image classification in remote sensing.

Image classification is the process of grouping pixels into meaningful land-cover classes based on their spectral properties. It converts raw satellite data into thematic maps such as vegetation, water bodies, or built-up areas.

SECTION C

Attempt any one (7 marks)

(a) Monitoring land-use and land-cover changes using remote sensing.

Remote sensing enables regular monitoring of land-use and land-cover changes by comparing satellite images acquired at different times. It helps detect deforestation, urban expansion, agricultural changes, and water body shrinkage. Multitemporal analysis provides accurate, timely, and cost-effective information for planning and environmental management.

(b) Digital image enhancement and its role in image interpretation.

Digital image enhancement improves visual quality of images by modifying pixel values. Techniques such as contrast stretching, filtering, and band ratioing highlight important features and suppress noise. Enhanced images improve interpretation accuracy and help analysts identify land-cover features more easily.