Applied Geology · Remote Sensing & GIS

Remote Sensing & GIS

The electromagnetic spectrum, sensor resolution, vegetation indices and GIS data models — mapping geology from above.

PART 1

Topic Breakdown & Traps

The Engineering Principle

Remote sensing records reflected/emitted electromagnetic radiation. Surfaces have diagnostic spectra: healthy vegetation reflects strongly in the near-infrared (basis of NDVI), water absorbs it. A sensor is characterised by spatial (smallest resolvable ground detail), spectral (number/width of bands), radiometric and temporal (revisit) resolution. GIS stores spatial data as raster (continuous fields like DEMs) or vector (discrete features), enabling overlay, lineament mapping and spatial analysis.

The Core Formula Matrix

Photo scale:

scale = f / H

; denominator

= H / f

.

Ground distance: map distance × scale denominator.

EM relation:

c = f λ

.

NDVI:

\frac{N I R - R e d}{N I R + R e d} \in [- 1, + 1]

The ‘IIT Traps’

⚠
Vegetation = high NIR. Don't expect vegetation to peak in visible green alone.
⚠
Spatial vs spectral. Spatial = ground detail; spectral = number of wavelength bands.
⚠
Raster for continuous fields. Elevation/DEM is best as a raster, not points.

📚 Standard references

Remote Sensing and Image Interpretation — Lillesand, Kiefer & Chipman
Concepts and Techniques of GIS — Lo & Yeung

PART 2

Progressive 3-Tier Question Suite

Q1BASIC1 Mark · MCQ

Healthy green vegetation reflects most strongly in the

Q2MEDIUM1 Mark · MCQ

The ability of a sensor to distinguish two adjacent objects on the ground is its

Q3MEDIUM2 Marks · NAT

On a

1 : 20000

map, two points are

150

mm apart. The ground distance is _____ m.