THEORY EXAMINATION (SEM–IV) 2016-17 GEOINFORMATICS

Course: B.Tech (Civil Engineering)
Subject Code: CE402
Subject Title: Geoinformatics
Exam Type: Theory (Semester IV, 2016–17)
Duration: 3 Hours
Maximum Marks: 100

SECTION – A (10 × 2 = 20 Marks)

Short, definition-based questions that test conceptual clarity and understanding of remote sensing and photogrammetry.

Key Topics:

Stereoscopy:
The technique of perceiving depth in overlapping aerial photographs, giving a 3D view of terrain.

Relief Displacement:
Apparent shift of an object in a photograph due to height differences from the mean ground level.

Parallax:
The apparent change in object position when viewed from different angles; used for height measurement in aerial photos.

Active Remote Sensing:
Uses its own source of energy (e.g., RADAR, LiDAR) to collect data.

Passive Remote Sensing:
Records natural energy (sunlight) reflected or emitted from Earth’s surface.

Flight Planning:
The process of determining flight lines, overlaps, and altitudes for aerial photography missions.

Sun-Synchronous Satellites:
Orbits that pass over the same area at the same local solar time (e.g., Landsat, SPOT).

Geo-Synchronous Satellites:
Remain fixed over one point on Earth (e.g., INSAT, Meteosat).

Resolution:
The ability of a sensor to distinguish between two close objects (spatial, spectral, radiometric, temporal).

Spectral Reflectance Curve:
Graph showing how different surfaces reflect electromagnetic radiation across wavelengths (useful for vegetation, soil, and water studies).

SECTION – B (5 × 10 = 50 Marks)

Attempt any five. These questions involve derivations, short notes, and conceptual applications in photogrammetry, remote sensing, and GIS.

Topics Covered:

(a) Derivation of Scale of a Vertical Photograph

Formula:

• Scale=fH−h\text{Scale} = \frac{f}{H - h}Scale=H−hf​

where f = focal length, H = flying height above datum, h = height of ground point above datum.

Used to compute distances and coordinates from aerial photos.

(b) Relief Displacement Derivation:

d=r×hHd = \frac{r \times h}{H}d=Hr×h​

where r = radial distance on photo, h = height of object, H = flying height.

(c) Numerical Example:
Given camera focal length = 37.5 cm, flight height = 7200 m, print size = 22.5 cm × 22.5 cm, ground height = 2500 m.
→ Find photo scale and air base length assuming 50% overlap.

(d) Information Extraction from Aerial Photograph

Visual interpretation (tone, texture, pattern, shape, size, shadow).

Digital methods (classification, edge detection, image fusion).

(e) Satellite Image – Characteristics & Formats

Raster data, digital pixels, spectral bands (multispectral/hyperspectral).

Stored as GeoTIFF, HDF, or NetCDF formats.

(f) Image Enhancement

Techniques: contrast stretching, filtering, histogram equalization, false-color composite.

Enhances visibility and interpretability of satellite data.

(g) Land Use / Land Cover Classification (LULC)

Process of categorizing pixels into built-up, forest, agriculture, water, etc.

Types: supervised and unsupervised classification.

(h) GIS and Its Applications

Definition: a system for capturing, storing, analyzing, and managing spatial data.

Applications: urban planning, disaster management, watershed analysis, transportation, and environmental monitoring.

SECTION – C (2 × 15 = 30 Marks)

Attempt any two. These questions focus on GPS concepts and applications.

(3) Segments of GPS

Space Segment: 24+ satellites orbiting Earth at ~20,200 km altitude.

Control Segment: Ground stations for monitoring and correction.

User Segment: Receivers used for navigation, mapping, and surveying.

(4) Kinematic vs Differential GPS

(5) How GPS Revolutionized Life

Everyday navigation (Google Maps, logistics, aviation).

Precision farming and surveying.

Disaster management and rescue operations.

Military and communication synchronization.

Integration with GIS for accurate spatial data mapping.

Key Units Covered

Summary

This Geoinformatics (CE402) paper blends theoretical knowledge with applied problem-solving.
It tests:

Fundamental aerial surveying principles,

Remote sensing interpretation,

GIS concepts, and

GPS-based data acquisition and positioning.

To perform well, students should:

Memorize formulas (scale, relief displacement).

Understand image interpretation techniques.

Know practical GIS and GPS applications.