BAB 2 Imagery

TOPIC 2
TYPES OF IMAGERY
2.1 Understand types of image
2.1.1 Interpret photography image (black and
white )
2.1.2 Interpret satellite image (color image,
infra-red image, thermal image)
2.1.3 Implement the technique of composite
image
2.2 Understand the techniques of RADAR (SAR
and SLAR)
2.2.1 Evaluate the technique of RADAR
TYPES OF IMAGES
Photographic Image
Non Photographic image
Satellite Image
Radar Image
Electromagnetic energy may be
detected either photographically or

electronically.
The photographic process uses
chemical reactions on the surface of
light-sensitive film to detect and
record energy variations.
It is important to distinguish between
the terms images and photographs in
remote sensing
An image refers to any pictorial
representation, regardless of what

wavelengths or remote sensing device
has been used to detect and record the
electromagnetic energy.
A photograph refers specifically to
images that have been detected as well
as recorded on photographic film.
Photos are normally recorded over the
wavelength range from 0.3 m to 0.9

m - the visible and reflected infrared.
A photograph could also be
represented and displayed in a

digital format by subdividing the
image into small equal-sized and
shaped areas, called picture
elements or pixels, and representing
the brightness of each area with a
numeric value or digital number.
INFRARED
In 1903 or 1904 the first reliable black and white infrared
film was developed in Germany.

The film emulsion was adjusted slightly from regular film to
be sensitive to wavelengths of energy just slightly longer

than red light and just beyond the range of the human eye.
The scientific community, however, has made continuous
use of the film technology.

Color infrared film is often called "false-color" film. Objects
that are normally red appear green, green objects (except

vegetation) appear blue, and "infrared" objects, which
normally are not seen at all, appear red.
The primary use of color infrared photography is
vegetation studies.
This is because healthy green vegetation is a very strong
reflector of infrared radiation and appears bright red on

color infrared
SATELLITE IMAGE
COLOR INFRARED
Color infrared film is often called "false-color" film.

Objects that are normally red appear green, green objects (except
vegetation) appear blue, and "infrared" objects, which normally are not seen
at all, appear red.
The primary use of color infrared photography is vegetation studies.
This is because healthy green vegetation is a very strong reflector of
infrared radiation and appears bright red on color infrared photographs.
Thermal Image
Thermal infrared radiation refers to electromagnetic waves with a
wavelength of between 3.5 and 20 micrometers.

Most remote sensing applications make use of the 8 to 13
micrometer range.
The main difference between THERMAL infrared and the infrared
discussed above is that thermal infrared is emitted energy,

whereas the near infrared (photographic infrared) is reflected
energy.
Limitations of Thermal Infrared Imaging
It is very expensive.
Most thermal imaging systems have very strict operational

parameters.
For example, the detector must be kept extremely cold during use.

Thermal infrared imaging systems are notoriously difficult
to calibrate.
The data collected has extensive processing

requirements. A PC isn't going to cut it.
Thermal images can be quite difficult to interpret when

compared with other types of imagery.
Thermal imagery is NOT geometrically correct.
Thermal images of water measure only the very top layer

of the water. They tell you nothing of the water's characteristics
below the top few micrometers.
IMEJ FOTOGRAFI
Merupakan bentuk penderiaan jauh
lama
Fotografi diambil dari belon, kapal
terbang dan satelit
Imej menggunakan filem
Imej yang dihasilkan bergantung
pada jumlah cahaya
Pengesanan Cuma dilakukan pada
cahaya nampak
Antara jenis foto:

Fotografi hitam putih (visible)
Pendedahan cahaya dilakukan ke
atas filem panchromatic di mana
emulsi sensitif kepada spektrum
nampak
Pada jalur (0.36um-0.72um)
Imej panchromatic akan memberikan
imej dalam bentuk tone kelabu
Fotografi Warna( Visible)

Pendedahan cahaya tampak dilakukan ke
atas filem warna
Mengandungi pelbagai lapisan emulsion
di atas base
Yang mana setiap lapisan peka kepada
berlainan jalur panjang gelombang
cahaya
Mengandungi berlainan dye (biru, hijau,
merah)
Imej warna yang dihasilkan akan
menggambarkan keadaan warna sebenar
dan dikenali sebagai (true colour)
Foto ini boleh digunakan untuk
pentaksiran imej tetapi terdapat

masalah seperti perbelanjaan tinggi
dan gangguan atmosfera
Penuras kuning(yellow filter) diletakkan
pada lapisan emulsion untuk menahan
drpd menerima spektrum biru untuk
menghilangkan kesan hase yang
terjadi drpd proses serakan rayleigh
Fotografi warna Inframerah

Filem yang dipasang dengan filem
standard panchroamatic atan filem

warna biasa merakam pandangan yang
dapat dilihat oleh mata
Untuk mendapat melihat pandangan
yang menjangkau spektrum visible
yang tdk dpt dilihat oleh mata
Maka filem yang peka melebihi
spektrum digunakan iaitu filem infrared
(0.7-1.5um)
Top: tree photographed in the near infrared

range. Bottom: same tree in the
visible part of the spectrum.
Imej Bukan Fotografik

Imej ini untuk spektrum jenis
gelombang panjang seperti

inframerah termal dan radar
Imej ini berkembang luas kerana
ketinggian pelantar bertambah maka
penderiaan untuk cahaya nampak
sukar kerana atmosfera tinggi
Contoh imej: RADAR
RADAR
RADAR
Adalah alat pengukuran jarak dengan
mengukur masa denyut dipancarkan

kepada objek dan dibalikkan semula
ke antena
RADAR (Radio Detection And

Ranging)
Radar merupakan sistem pengesan
objek yang mengesan gelombang

elektromagnetik bagi menentukan
jarak,altitud,arah.
Tenaga gelombang mikro
dipancarkan daripada antena
(transmitter) dalam bentuk short
burst atau denyut(pulses) kpd objek
Kemudian dipantulkan semula pada
penderia
Masa perjalanan gema(echo) diukur
secara elektronik dan ditukar kpd nilai

jarak antara alat pemancar dan objek
Jumlah tenaga yang dipantulkan
bergantung kpd saiz, kekasaran dan
kandungan serta sifat elektrik
Apabila tenaga diterima oleh penderia
ia ditukar kpd isyarat elektronik
Dengan bantuan cathode ray tube(CRT)
ia boleh ditukar ke dlm btk imej
A long-range radar antenna, known as ALTAIR,

used to detect and track space objects in
conjunction with ABM testing at the
Ronald Reagan Test Site on the Kwajalein atoll
Permukaan yang bersudut tepat
dengan pancaran akan memberikan

jumlah tenaga pembalikan paling
tinggi dan pada imej tone akan
menjadi terang
Manakala permukaan yang condong
akan memberi imej sedikit gelap
seperti bayang
Imaging and Non-Imaging

Systems
Radar systems may or may not be
imaging systems. A well known

example of a non-imaging system is
a doppler radar system. These
systems are used (for example) to
measure vehicle speeds by
measuring the frequency, or doppler
shift between transmitted and return
signals.
Beware speedsters: L/Kpl Noremin Yusop using the new radar gun to
catch speeding vehicles during Ops Sikap XXI on the North- South
Expressway near the Bangi toll plaza Monday. Highway users who will be
enjoying free travel or getting discounts for the coming Chinese New Year
should make sure that they do not lose them to speeding fines. The radar
gun can detect speeding cars from as far as 1km away.
Plan position indicators (PPI) produce a type of image. These radars

use a circular display screen to indicate objects surrounding the rotating
antenna. They acommonly used for weather monitoring, air traffic
control and navigational systems. The spatial resolution of the view map
of the area under surveillance is too coarse to be used in remote
sensing applications.
Active and Passive Imaging Systems
Imaging radar systems can be active or
passive.
Active radar systems transmit short bursts
or 'pulses' of electromagnetic energy in the
direction of interest and record the origin
and strength of the backscatter received
from objects within the system's field of
view.
Passive radar systems sense low level
microwave radiation given off by all objects
in the natural environment.
Radar imaging systems such as ERS (European

Remote Sensing Satellite), JERS (Japan Earth
Resources Satellite), and RADARSAT-1 are active
systems. They both transmit and receive energy.
Microwave scanning radiometers only receive
microwave energy.
One advantage of active radar sensing
systems is that, since they provide

their own source of energy, they can
collect data at any time of the day or
night.
Passive sensors - optical, thermal, and
microwave - rely on receiving the
naturally emitted or the sun's reflected
energy from the Earth's surface.
Ciri-ciri imej radar

Imej radar menyerupai gambarfoto
tetapi tdk sama terutama dlm herotan

geometri
Herotan sisi (lateral) dlm imej radar
bergantung kpd objek yang bersifat
tinggi
Imej radar yang diambil dari kapal
udara dan yang diambil dari kapal
angkasa mempunyai ciri yang berbeza
Ciri utama imej radar

Pengesanan selari dalam satu
garisan (scan lines) dan bersudut

tepat dgn arah penerbangan
Ton terang dan gelap
menggambarkan tindakbls dengan
permukaan bumi atau jumlh tenaga
yang dibalikkan
Erotan geometri iaitu anjakan satu
dimensi kesan imbasan sisi (lateral

scanning akan kelihatan jelas bagi
permukaan imej jasad timbul
Kesan ini bergantung kepada sudut
pandang dan sudut tunduk serta
jarak lateral
Erotan menjadi lbh besar bagi imej
yang lbh jauh dari arah penerbangan
Kesan yang timbul seperti terlalu
baringan (layover), bayang(shadow).
Band
name
Frequency
range
Wavelength
range
Notes
HF
330 MHz
10100 m
coastal radar systems, over-the-horizon radar (OTH) radars; 'high frequency'
< 300MHz
1 m+
'P' for 'previous', applied retrospectively to early radar systems
VHF
30330MHz
0.96 m
Very long range, ground penetrating; 'very high frequency'
UHF
3001000MHz
0.31 m
Very long range (e.g. ballistic missile early warning), ground penetrating, foliage
penetrating; 'ultra high frequency'
12 GHz
1530 cm
Long range air traffic control and surveillance; 'L' for 'long'
24GHz
7.515cm
Terminal air traffic control, long-range weather, marine radar; 'S' for 'short'
48GHz
3.757.5cm
Satellite transponders; a compromise (hence 'C') between X and S bands;

weather
812GHz
2.53.75cm
Missile guidance, , weather, medium-resolution mapping and ground

surveillance; in the USA the narrow range 10.525GHz 25MHz is used for
airport radar. Named X band because the frequency was a secret during WW2.
Ku
1218GHz
1.672.5cm
high-resolution
1824GHz
1.111.67cm
from German kurz, meaning 'short'; limited use due to absorption by water
vapour, so Ku and Ka were used instead for surveillance. K-band is used for
detecting clouds by meteorologists, and by police for detecting speeding
motorists. K-band radar guns operate at 24.150 0.100GHz.
Ka
2440GHz
0.751.11cm
mapping, short range, airport surveillance; frequency just above K band (hence
'a') Photo radar, used to trigger cameras which take pictures of license plates of
cars running red lights, operates at 34.300 0.100GHz.
mm
40300GHz
7.5mm 1mm
millimetre band, subdivided as below. The frequency ranges depend on

waveguide size. Multiple letters are assigned to these bands by different
groups. These are from Baytron, a now defunct company that made test
equipment.
4060GHz
7.5mm 5mm
Used for Military communication.
5075GHz
6.04mm
Very strongly absorbed by the atmosphere.
6090GHz
6.03.33mm
75110GHz
2.7 4.0mm
used as a visual sensor for experimental autonomous vehicles, high-resolution

meteorological observation, and imaging.
UWB
1.610.5GHz
18.75cm
used for through-the-wall radar and imaging systems
Synthetic Aperture RADAR

(SAR)
SAR image of Death Valley

colored using polarimetry
Penderiaan Infra Merah Thermal

Penderiaan haba dinamakan
thermography iaitu pengukuran dan

merekod haba objek dibumi
Jarak gelombang antara 3.0-5.0 um dan
8.0-14.0um.
Penderiaan dibuat dari bahan yang peka
kpd perubahan suhu raksa (mercury)
Konsep deria sama dengan penderiaan
bkn fotografi
PENDERIAAN LAMPAU UNGU

(ULTRA-UNGU)
Merupakan penderiaan gelombang pendek
(0.01m-0.4m)
Penderiaan gelombang ini sukar dilaksanakan
kerana kesan atmosfera yg tinggi
Walaubagaimanapun imej boleh dihasilkan
menggunakan alat kamera yg mempunyai
kanta dan penapis khas
Imej yg dihasilkan menjadi tone gelap utk
objek putih spt salji dan objek gelap akan jd
tone terang
Penderiaan ini sesuai untuk kerja
pengawasan pencemaran seperti tumpahan
minyak.

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TOPIC 2

Electromagnetic energy may be

detected either photographically or

An image refers to any pictorial

representation, regardless of what

Photos are normally recorded over the

wavelength range from 0.3 m to 0.9

A photograph could also be

represented and displayed in a

film was developed in Germany.

be sensitive to wavelengths of energy just slightly longer

use of the film technology.

that are normally red appear green, green objects (except

reflector of infrared radiation and appears bright red on

Color infrared film is often called "false-color" film.

wavelength of between 3.5 and 20 micrometers.

discussed above is that thermal infrared is emitted energy,

Limitations of Thermal Infrared Imaging

Most thermal imaging systems have very strict operational

The data collected has extensive processing

Thermal images can be quite difficult to interpret when

Thermal imagery is NOT geometrically correct.

Thermal images of water measure only the very top layer

Antara jenis foto:

Fotografi Warna( Visible)

Foto ini boleh digunakan untuk

pentaksiran imej tetapi terdapat

Fotografi warna Inframerah

standard panchroamatic atan filem

Top: tree photographed in the near infrared

Imej Bukan Fotografik

gelombang panjang seperti

mengukur masa denyut dipancarkan

RADAR (Radio Detection And

objek yang mengesan gelombang

Masa perjalanan gema(echo) diukur

secara elektronik dan ditukar kpd nilai

A long-range radar antenna, known as ALTAIR,

Permukaan yang bersudut tepat

dengan pancaran akan memberikan

Imaging and Non-Imaging

imaging systems. A well known

Plan position indicators (PPI) produce a type of image. These radars

Active and Passive Imaging Systems

Imaging radar systems can be active or

Radar imaging systems such as ERS (European

One advantage of active radar sensing

systems is that, since they provide

Ciri-ciri imej radar

tetapi tdk sama terutama dlm herotan

Ciri utama imej radar

garisan (scan lines) dan bersudut

Erotan geometri iaitu anjakan satu

dimensi kesan imbasan sisi (lateral

Kesan yang timbul seperti terlalu

baringan (layover), bayang(shadow).

coastal radar systems, over-the-horizon radar (OTH) radars; 'high frequency'

'P' for 'previous', applied retrospectively to early radar systems

Very long range, ground penetrating; 'very high frequency'