THEORY EXAMINATION (SEM–IV) 2016-17 GEOINFORMATICS

Course: B.Tech (Civil Engineering)
Subject Code: NCE402
Subject Title: Geoinformatics
Exam Type: Theory (Semester IV, 2016–17)
Duration: 3 Hours
Maximum Marks: 100

Note: Answers must be concise. Assume missing data for numerical problems.

SECTION – A (10 × 2 = 20 Marks)

Short conceptual questions testing clarity of geospatial fundamentals:

Stereoscopy: Technique for obtaining 3D depth perception from two overlapping aerial photos.

Relief Displacement: Apparent shift in object position due to elevation difference on terrain.

Parallax: Apparent displacement of object positions when viewed from different angles — used for height determination in photogrammetry.

Active Remote Sensing: Sensors that emit energy (e.g., RADAR, LiDAR).

Passive Remote Sensing: Uses natural sunlight reflected from surfaces (e.g., Landsat, IRS).

Flight Planning: Determining altitude, camera orientation, and overlap for aerial survey operations.

Sun-Synchronous Satellites: Cross equator at the same local solar time daily (ideal for Earth observation).

Geo-Synchronous Satellites: Orbit synchronously with Earth’s rotation, appearing fixed (e.g., INSAT).

Resolution: Smallest detectable feature — spatial, spectral, temporal, or radiometric.

Spectral Reflectance Curve: Graph showing reflectivity of materials (soil, vegetation, water) across wavelengths.

SECTION – B (5 × 10 = 50 Marks)

Attempt any five — focuses on derivations, numericals, and conceptual explanations.

a) Scale of a Vertical Photograph

Derive:

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

where f = focal length, H = flying height above datum, h = elevation of terrain point.
Also explains how ground distances and coordinates are obtained using scale factors.

b) Relief Displacement

Define relief and derive:

d=r×hHd = \frac{r \times h}{H}d=Hr×h​

where r = radial distance from photo center, h = object height above datum, H = flying height.

c) Numerical Problem

Given:

Focal length = 37.5 cm

Flight height = 7200 m

Overlap = 50%

Print size = 22.5 × 22.5 cm

Ground height = 2500 m

Find:
Scale of the photograph
Airbase length

d) Information Extraction from Aerial Photograph

Visual interpretation: tone, texture, size, pattern, shape, shadow.

Digital interpretation: classification, contrast enhancement, histogram stretching, filtering.

e) Satellite Image

Define; describe characteristics (resolution, radiometry, spectral range) and formats (GeoTIFF, HDF, IMG).

f) Image Enhancement

Used to improve interpretability:

Techniques include contrast stretching, edge enhancement, smoothing, and false-color composites.

g) Land Use / Land Cover (LULC) Classification

Classification of surface features (water, forest, agriculture, built-up).

Methods: supervised and unsupervised classification using digital imagery.

h) GIS – Definition & Applications

GIS (Geographic Information System) integrates spatial and attribute data for analysis.

Applications:

Urban planning

Water resource mapping

Transportation network analysis

Disaster management

Environmental monitoring

SECTION – C (2 × 15 = 30 Marks)

Attempt any two — focuses on GPS (Global Positioning System) applications and understanding.

3. GPS Segments

Explain:
Space Segment – satellite constellation (24+ satellites in 6 planes).
Control Segment – ground stations for orbit control and correction.
User Segment – GPS receivers decoding signals for position, velocity, and time.

4. Kinematic vs Differential GPS

5. GPS Revolution in Daily Life

GPS impacts almost every field:

Navigation (cars, ships, aviation)

Telecom tower synchronization

Precision agriculture

Military & disaster management

Real-time GIS mapping and logistics

Key Units Summary