Fundamentals of remote sensing

1. Fundamentals of remote sensing
By
Ashok Peddi

2. Satellite image
Remote sensing is the science of acquiring information about the Earth's
surface without actually being in contact with it. This is done by sensing and
recording reflected or emitted energy and processing, analysing, and applying
that information.
Remote Sensing can be done by two different ways
1)Satellites –satellite Images 2)Aircrafts-Arial Photographs
Aerial photography

3. Aerial photography Satellite image
Examples

4. To analyze(Visual Interpretation) the satellite imagery we use
different combination of bands where it will produce two
variety of(composite) images
1)True Color Composite(RGB)
2)False Color Composite other( than RGB)
False Color True color

5. Quickbird
PAN – 61 cm

6. IKONO
S
MSS/
XS – 4
m
Bagdad
, Iraque

7. What is a satellite
image?
Satellite imagery consists of photographs
of Earth or other planets made by means
of artificial satellites which also gives an
opportunity to process the image and
conclude with analysis depending on your
requirement.

8. Blue Green Red
Urban area
Urban area
River
3500 m
The different Bands
Vegetation
Description of a Satellite Image

9. Landsat TM 30 m
SPOT XS 10 m
NOAA/AVHRR 1100 m
IKONOS 4 m
70
23
10
120
40
The value retained in each pixel is designated by digital number and it
translates the solar energy reflected by the earth surface (covered by the
pixel).
Spatial resolution

10. Radiometric Resolution

11. Blue Green Red
Urban area
Urban area
River
3500 m

12. Gree
n
RedBlue
Near Infrared Middle Infrared Middle Infrared
TM 1 TM 2 TM 3
TM 4 TM 5 TM
7
7 4 3
4 3 2
Spectral Resolution

13. Components of a remote sensing system
A – Energy source of illumination
B – Interaction with the atmosphere
C – Interaction with the target
F – Transmissions, reception and processing
E – Recording of energy by the sensor
G – Interpretation and analysis

14. v = frequency
(number of cycles per second
passing a fixed point)
Wavelength is measured in meters (m) or some factor of meters such as nanometres
(nm, 10
-9
m), micrometers (μm, 10
-6
m) or centimeters (cm, 10
-2
m).
Frequency is normally measured in hertz (Hz), equivalent to one cycle per second, and
various multiples of hertz.

15. Quantity of radiant energy is expressed in energy units.
Quality of radiant energy is characterised by frequency
(u) or wavelength (l).
c = l u
c - velocity of light (3x10
8
m/s)
Wavelength and frequency are inversely related to each
other:
• the shorter the wavelength, the higher the
frequency;
• the longer the wavelength, the lower the frequency.

17. Electromagnetic spectrum
*The energy in remote sensing is in the form of
electromagnetic radiation.Electro magnetic Radiation is
a particular form of energy emitted and absorbed by
charged particles
The electromagnetic spectrum is the range of all
possible frequencies of electromagnetic
radiation.
*
The "electromagnetic spectrum" of an
object has a different meaning, and is instead the
characteristic distribution of electromagnetic
radiation emitted or absorbed by that particular
object.

19. The visible portion of the spectrum is a
very small part of the whole spectrum:
•blue - 0.4 a 0.5 mm
•green - 0.5 a 0.6 mm
•red - 0.6 a 0.7 mm.
1 mm = 10
-6
m
The wavelengths smaller than 0.4
mm entails:
• gamma rays
• x rays
• ultraviolet radiation

20. The part of the electromagnetic spectrum with
wavelengths larger than 0.7 mm entails:
• infrared (0.7-10 mm),
• microwaves (1mm-1m)
• radio waves.
Infrared goes from 0.7 mm to 10 mm and can
be divided in three areas:
• Near infrared (0.7-1.0 mm),
• medium infrared (1.3-3.0 mm)
• thermal infrared (> 3 mm).

21. Interaction of electromagnetic radiation
with atmosphere
The atmosphere has a strong effect on the quantity
and quality of the electromagnetic radiation captured
by the satellite.
The atmosphere effect varies with:
• radiation path (airplane, satellite)
• wavelength
• atmospheric conditions (particles, gases, …)
• ...

22. Before radiation used for remote sensing reaches the
Earth's surface it has to travel through some distance of
the Earth's atmosphere.
Particles and gases in the atmosphere can affect the
incoming light and radiation. These effects are caused
by the mechanisms of:
• scattering
• absorption.
What is the effect of atmosphere in the satellite
images?
• Atmosphere reduces contrast
• Atmosphere may blur the images
• Atmospheres may reduce the quantity of
radiation

23. I hope that was useful 
@ashokped
Thank you!