Introduction to
Remote Sensing (RS) & Optical Data
© Asian Institute of Technology, 2014, All Rights Reserved
Contents
• RS Definition
• Characteristics (Altitude, Orbit, and Sensor)
• Process of RS
• Sensor (Optical, Microwave)
• Law of Conservation Energy (Absorbed, Transmitted,
Reflected)
• Electromagnetic Radiation
• Electromagnetic Spectrum
• Wavelength and Frequency
• Spectral Reflectance respect to natural objects
• Color Composite
• Resolutions (Spatial, Temporal, Spectral, and Radiometric)
© Asian Institute of Technology, 2014, All Rights Reserved
What is remote sensing
Remote sensing refers to the activities of recording/observing/perceiving (sensing) objects or
Remote Sensing
events at far away (remote) places.
In remote sensing, the sensors are not in direct contact with the objects or events being
Sensor
observed.
The information needs a physical carrier to travel from the objects/events to the sensors
Electromagnetic
Radiatiion
through an intervening medium. The electromagnetic radiation is normally used as an
information carrier in remote sensing.
Characteristics of a remote sensing Satellite
 Altitude: Altitude is the height of operation of a remote sensing satellite . The nature of
an imagery captured by a remote sensing satellite varies depending on the altitude.
Geostationary/Communication Satellite
Parked in the space 35,900 km
Platform
(global communication, weather forecast,
satellite TV, radio)
Satellite (Landsat, MOS)
700-900 km
Space Shuttle
185-575 km
Light Plane
Aerial Photography
1.2-3.5 km
Helicopter
0.3 km-
 Orbit
 Sensors
Source: http://gis.mapsofworld.com/remote-sensing/remote-sensing-satellite.html
High-flying Aircraft
Air SAR
10-12km
Characteristics of a remote sensing Satellite
 Altitude
 Orbit:
Sun synchronous orbit - Many remote sensing platforms are
designed to follow an orbit (basically north-south) which, in conjunction
with the Earth's rotation (west-east) so called ‘Sun synchronous orbit’
allows them to cover most of the Earth's surface over a certain period of
time.

In this orbit the remote sensing satellite allows to cover
most of the earth’s surface over a certain period of time
(crosses the same point at approximately same (local)
time).

The
time
interval
after
which
a
remote
sensing
satellite repeats its path is called repeat circle.
 Sensor
Source: http://gis.mapsofworld.com/remote-sensing/remote-sensing-satellite.html
http://satellites.spacesim.org/
Characteristics of a remote sensing Satellite
 Altitude
 Orbit:
Geostationary orbit – Satellites at very high altitudes, which view
the same portions of the earth’s surface at all time. An orbit
revolves at speed which match the rotation of the Earth. A
worldwide
network
of
operational
geostationary
meteorological
satellites

Geostationary Operational Environmental Satellite (GOES) The United States

Meteosat [Eumetsat] - Launched by the European Space
Agency and operated by the European Weather Satellite
Organization,

MTSAT
-
The
Japanese
Satellite,
Operated
by
JMA,
Monitoring typhoons and other weather condition in AsianOceanic Region
 Sensor
Source: http://gis.mapsofworld.com/remote-sensing/remote-sensing-satellite.html
http://satellites.spacesim.org/
Characteristics of a remote sensing Satellite
 Altitude
 Orbit
 Sensors: Sensors are of two kinds-passive and active (in term of energy source).
Passive sensors are those which accept reflectance from natural object whereas active
sensors accept reflectance from man-made objects
Source: http://gis.mapsofworld.com/remote-sensing/remote-sensing-satellite.html
Swath
 As a satellite orbits around the Earth, the sensor "sees" a certain portion of the Earth's
surface. The area imaged on the surface, is referred to as the swath. generally vary between
tens and hundreds of kilometres wide.
Source: http://gis.mapsofworld.com/remote-sensing/remote-sensing-satellite.html
http://satellites.spacesim.org/
Source: National Resources Canada http://www.nrcan.gc.ca/earth-sciences/
Consecutive Path
 As the satellite orbits the Earth from pole to pole, its
east-west position would not change if the Earth did
not rotate. However, as seen from the Earth
 Satellite path is shifting westward because the Earth is
rotating (from west to east).
 This apparent movement allows the satellite swath to
cover a new area with each consecutive pass.
Source: http://glovis.usgs.gov/
Process of Remote Sensing
1. Energy Source or Illumination (A) - an energy source
illuminates or provides electromagnetic energy to the
Earth’starget
energy
budget
of interest.
2. Radiation and the Atmosphere (B) - as the energy
travels from its source to the target, it will come in
contact with and interact with the atmosphere it passes
through.
3. Interaction with the Target (C) - interacts with the
target depending on the properties of both the target and
the radiation.
4. Recording of Energy by the Sensor (D) - after the
energy has been scattered by, or emitted from the
target, we require a sensor to collect and record the
electromagnetic radiation.
5. Transmission, Reception, and Processing (E) - the energy recorded by the sensor has
to be transmitted, often in electronic form, to a receiving and processing station where the
data are processed into an image (hardcopy and/or digital).
6. Interpretation and Analysis (F) - the processed image is interpreted, visually and/or
digitally or electronically, to extract information about the target which was illuminated.
7. Application (G) - Apply the information we have been able to extract from the imagery
about the target in order to better understand it, reveal some new information, or assist in
solving a particular problem.
Source: Natural Resources Canada, http://www.nrcan.gc.ca/earth-sciences
© Asian Institute of Technology, 2014, All Rights Reserved
Why Remote Sensing
 Unobstruction
 Automated System/Near-real Time
 Useful for extreme conditions
 spatial and temporal coverage Advantage
 Extends our senses or beyond Normal Camera capabilities
 No “Political” Boundary
Sensors
Every material on earth shows its own strength of reflection in each wavelength when
it is exposed to the EM waves.
Sensors aboard a platform are capable to acquire the strength of reflection and radiation in
each wavelength.
Strength of reflection and radiation of EM
waves from plants, earth and water in each
wavelength.
© Asian Institute of Technology, 2014, All Rights Reserved
Type of Sensors
Optical Sensor
Measuring/observing
Microwave Sensor
visible
Measuring
the
microwave
lights and infrared rays (near
energy
infrared,
ground or sea back to the
intermediate
infrared, thermal infrared).
scattered
by
the
sensors.
Visible/NIR RS
Thermal IR Remote Sensing
Passive Microwave
Active Microwave (RADAR)
Acquire visible light
and
near
infrared
rays
of
sunlight
(detect
solar
radiation)
reflected
or
scattered
by
objects
on
the
ground.
 Acquire thermal infrared
rays, which is radiated
from land surface heated
by sunlight.
 Observe
the
high
temperature areas, such
as volcanic activities.
 Examine
Strength
of
radiation,
we
can
understand
surface
temperatures of land and
sea, and status of volcanic
activities and forest fires.
 Can observe at night when
there is no cloud.
Objects at the earth's
surface
also
emit
microwaves
at
relatively low energy
levels. When a sensor
detects
microwave
radiation
naturally
emitted by the earth,
that
radiation
is
called
passive
microwave
Satellites carry their own
"flashlight"
emitting
microwaves
to
illuminate
(lighten) their targets. The
images can thus be acquired
day and night. Microwaves
have an additional advantage
as they can penetrate clouds.
Source: EORC, JAXA, http://www.eorc.jaxa.jp/
Type of Sensors
Visible & Reflection IR
Remote Sensing
Radiation
Source >>
Object >>
The Sun
Reflectance
Thermal
Remote Sensing
Object
Thermal Radiation
(Emissivity, Temperature)
Microwave
Object
Microwave
Radiation
Radar
Backscattter
Coefficient
Spectral
Radiance >>
© Asian Institute of Technology, 2014, All Rights Reserved
What does a Sensor measure
Reflected energy from the Earth
Scattered energy from the Earth
Emitted energy from the Earth
Everything in nature has its own unique
distribution
(released)
of
and
reflected,
absorbed
emitted
radiation.
These spectral characteristics can be
used to distinguish one thing from
another or to obtain information about
shape, size and other physical and
chemical properties.
© Asian Institute of Technology, 2014, All Rights Reserved
Energy Source
Earth’s energy budget
Solar radiation is concentrated in shorter wavelength (ultraviolet, visible and SWI). Earth emits
longer Wavelength of Infrared (IR) to the atmosphere and eventually to the space.
© Asian Institute of Technology, 2014, All Rights Reserved
Relationship between three energy
interaction
When solar energy hits a surface (e.g. a leaf) that “the energy is either absorbed,
transmitted, or reflected in accordance with the Law of Conservation of Energy.” (McCloy,
1995):
EI (l) = EA (l) + ET (l) + ER(l)
EI
EA
ET
ER
=
=
=
=
Incident energy
Absorbed energy
Transmitted energy
Reflected energy
In remote sensing, we are most interested in measuring the radiation reflected from targets.
© Asian Institute of Technology, 2014, All Rights Reserved
EMR (Wave Theory)
 One of the form of ‘flow of energy’ that travel through space at
the same speed, c = 3 x 108 m/s, commonly known as the speed of
light.
 Electromagnetic radiation travels in waves, the form of the
electric and magnetic fields that make up electromagnetic waves
 In such a wave, time-varying electric and
magnetic fields are mutually linked with each
(i.e., visible light).
other at right angles and perpendicular to the
 An electromagnetic wave is characterized by a frequency and a
direction of motion.
wavelength.
c= ln
where;
l = wavelength (m)
n = frequency (Hz)
c = speed of light (3 x 108 m/sec)
Source: University of Colorado
http://www.colorado.edu/physics/2000/waves_particles
EMR (Particle Theory)
 Particle (Quantum) theory suggests that EM radiation is composed of
many discrete unit called photons or quanta through space.
 The energy of quantum is given as
Q=h n
where;
Q = Energy of Quantum (Joules, J)
h = 6.626 x 10-34 J/sec (Planck's Constant)
n = frequency (Hz)
Source: NASA, http://www.astronomynotes.com/light/s3.htm
Energy (Q) = h * n
Electromagnetic Radiation (Wave and
Particle Theory)
Wave Theory
Particle Theory
c= ln
Q= hn
where;
where;
Q = Energy of Quantum (Joules, J)
c = speed of light (3 x 108 m/sec)
l = wavelength (m)
h = 6.626 x 10-34 J/sec (Planck's Constant)
n = frequency (Hz)
n = frequency (Hz)
Energy (Q) = h * n
Energy (Q) = h*c
l
Source: NASA, http://www.astronomynotes.com/light/s3.htm
 The energy of a quantum is inversely proportional to its
wavelength.
 Thus, the longer the wavelength of EM radiation, the
lower its energy content.
Wavelength (µm)
10-6
10-5
10-4
10-3
10-2
10-1
1
101
102
103
104
105
106
107
The
electromagnetic
spectrum can be divided
Gammy Ray
X-Ray
Ultraviolet
Infrared
Microwave
Radio Waves
400
Shorter Wavelength
Higher Frequency,
Higher Energy
Blue
480
Green
540
Wavelength (nm)
several
wavelength
(frequency)
regions,
among
only
which
a
narrow band from about
Visible Spectrum
Ultraviolet Violet
into
Yellow
580
Red
Infrared
400 to 700 nm is visible to
the human eyes.
700
c= ln
Longer Wavelength
Lower Frequency,
Lower Energy
There
is
no
sharp
boundary between these
regions.
The
boundaries
shown
in
the
figures
are
approximate
and
there
between
regions.
are
two
above
overlaps
adjacent
Wavelength (µm)
10-6
10-5
Gammy Ray
10-4
X-Ray
10-3
10-2
10-1
101
1
Ultraviolet
Infrared
102
103
104
105
Microwave
106
107
Radio Waves
Visible
Infrared: 0.7 to 300 µm wavelength
 Near Infrared (NIR): 0.7 to 1.5 µm
 Short Wavelength Infrared (SWIR): 1.5 to 3 µm
 Mid Wavelength Infrared (MWIR): 3 to 8 µm
 Long Wanelength Infrared (LWIR): 8 to 15 µm
 Far Infrared (FIR): longer than 15 µm
The NIR and SWIR are also known as
the Reflected Infrared, referring to the
main infrared component of the solar
radiation reflected from the earth's surface.
The MWIR and LWIR are the Thermal
Infrared.
Microwaves: 1 mm to 1 m wavelength
The microwaves are further divided into different
frequency (wavelength) bands: (1 GHz = 109 Hz)
 P band: 0.3 - 1 GHz (30 - 100 cm)
 L band: 1 - 2 GHz (15 - 30 cm)
 S band: 2 - 4 GHz (7.5 - 15 cm)
 C band: 4 - 8 GHz (3.8 - 7.5 cm)
 X band: 8 - 12.5 GHz (2.4 - 3.8 cm)
 Ku band: 12.5 - 18 GHz (1.7 - 2.4 cm)
 K band: 18 - 26.5 GHz (1.1 - 1.7 cm)
 Ka band: 26.5 - 40 GHz (0.75 - 1.1 cm)
Wavelength units: 1 mm = 1000
µm; 1 µm = 1000 nm
Wavelength and Frequency
Wavelength: measured in metres (m) or
some factor of metres
 nanometres (nm, 10-9 metres)
Frequency:
measure
in
hertz
(Hz),
equivalent to one cycle per second
 Referred to the number of cycles of a
 micrometers (mm, 10-6 metres)
wave passing a fixed point per unit of
 centimetres (cm, 10-2 metres)
time.
© Asian Institute of Technology, 2014, All Rights Reserved
Wavelength and Frequency
 The counter shows how many wavelengths
of the top wave have passed the dashed
line
 In one second, the top wave moves three
wavelengths
to
the
right
so
its frequency is 3 Hz
 In one second, the bottom wave moves one
of its wavelengths in one second so
its frequency is 1 Hz
Source: http://www.astronomynotes.com/light/s3.htm
Short Wavelength (High Frequency)
Long Wavelength (Low Frequency)
Wavelength used in RS
Ka
Microwave band
W
Wavelength (cm)
0.3
Ultraviolet
Red
V O
Ku
X
K
1
C
3
Infrared
(IR)
L
S
10
30
P
100
Microwave
Yellow
Short wave IR
Green
Visible
Blue
Intermediate IR
Near IR
Thermal IR
Violet
Ultraviolet
0.4
0.7
1.3
3
8
14
© Asian Institute of Technology, 2014, All Rights Reserved
Type of Remote Sensing with respect to
Wavelength
Remote sensing is classified into three types with respect to the wavelength regions;
 Visible and Reflective Infrared Remote Sensing
 Thermal Infrared Remote Sensing and
 Microwave Remote Sensing
© Asian Institute of Technology, 2014, All Rights Reserved
Visible Spectrum
It is important to note that this is the only
portion of the EM spectrum we can associate
with the concept of colours.
© Asian Institute of Technology, 2014, All Rights Reserved
Infrared Region
The IR Region covers the wavelength range
from approximately 0.7 mm to 100 mm more than 100 times as wide as the visible
portion!
The IR region can be divided into two
categories
based
on
their
radiation
properties - the reflected IR, and the
emitted (released) or thermal IR.
© Asian Institute of Technology, 2014, All Rights Reserved
Microwave Region
Microwave region is used since
very early days of remote sensing
as this portion not depend on solar
radiation
hence
day
and
night
imaging capability
© Asian Institute of Technology, 2014, All Rights Reserved
Classification of Wavelength
Ultraviolet (UV)
region
Visible Spectrum
0.30 µm - 0.38 µm
This region is beyond the violet portion of the visible wavelength, and
hence its name. Some earth’s surface material primarily rocks and
minerals emit visible UV radiation. However UV radiation is largely
scattered by earth’s atmosphere and hence not used in field of remote
sensing.
0.4 µm - 0.7 µm
This is the light, which our eyes can detect. This is the only portion of
the spectrum that can be associated with the concept of color. Blue
Green and Red are the three primary colors of the visible
spectrum. They are defined as such because no single primary color
can be created from the other two, but all other colors can be formed by
combining the three in various proportions. The color of an object is
defined by the color of the light it reflects.
Violet
0.4 µm -0.446 µm
Blue
0.446 µm -0.5 µm
Green
0.5 µm - 0.578 µm
Yellow
0.578 µm - 0.592
µm
Orange
0.592 µm - 0.62
µm
Red
0.62 µm -0.7 µm
Infrared (IR)
Spectrum
0.7 µm – 1 mm
Wavelengths longer than the red portion of the visible spectrum are
designated as the infrared spectrum. British Astronomer William
Herschel discovered this in 1800. The infrared region can be divided into
two categories based on their radiation properties. Reflected IR (.7 µm 3.0 µm) is used for remote sensing. Thermal IR (3 µm - 35 µm) is the
radiation emitted from earth’s surface in the form of heat and used for
remote sensing.
Source: Shefali Aggarwal, Indian Institute of Remote Sensing
© Asian Institute of Technology, 2014, All Rights Reserved
Classification of Wavelength
Microwave Region
Radio Waves
1 mm - 1 m
This is the longest wavelength used in remote sensing. The
shortest wavelengths in this range have properties similar to
thermal infrared region. The main advantage of this spectrum is
its ability to penetrate through clouds
(>1 m)
This is the longest portion of the spectrum mostly used for commercial
broadcast and meteorology.
Source: Shefali Aggarwal, Indian Institute of Remote Sensing
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance respect to
Natural Objects
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Earth Surface
Satellite Data Acquisition
80%
Water (clear)
Vegetation (green)
70%
Dry bare soil (gray-brown)
60%
Blue Green Red NearIR
1
2
3
4
Mid IR
5
Mid IR
7
TM band
Reflectance
50%
Soil
40%
30%
Vegetation
20%
10%
Water
0%
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
2,2
2,4
2,6
Wavelength (µm)
Blue water as black, since water absorbs NIR wavelength energy
© Asian Institute of Technology, 2014, All Rights Reserved
The percent absorptance (dashed line), reflectance (solid line), and transmittance (dotted line) (McCloy, 1995).
Source:
The
North
Carolina
Geographic
Information
Coordinating
Council,
(http://www.nconemap.com/portals/7/documents/using_color_infrared_imagery_20110810.pdf)
July
2011
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Leaves
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Leaves:
Chlorophyll
A
chemical
compound
in
leaves
called
chlorophyll strongly absorbs radiation in
the red and blue wavelengths but reflects
green
wavelengths.
"greenest"
in
Leaves
the
appear
summer
Less chlorophyll in the leaves in autumn
appear red or yellow ( = red + green).
Chlorophyll absorb:
RED, BLUE
Reflect: Green/NIR
Healthy leaves act as excellent diffuse
reflectors
of
near-IR
wavelengths.
Measuring the near-IR reflectance is one way
that scientists can determine how healthy
vegetation is.
Reflectance from white and green germanium leaf
© Asian Institute of Technology, 2014, All Rights Reserved
Interaction of Visible, Near IR, and
Middle IR, EM Radiation with Water

Unlike vegetation or soil, the majority of radiant energy incident upon water is not
reflected, but is either absorbed or transmitted.

In visible wavelengths little is absorbed or reflected (< 5%), the majority being
transmitted.

Water absorbs near and middle IR wavelengths strongly, leaving little radiation to be
either reflected or transmitted.

Most water/land boundaries are therefore spectrally “sharp” in IR spectral range
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Water
Visible (Red) and near IR radiation is absorbed more by water than shorter visible
wavelengths. Thus water typically looks blue or blue-green due to stronger reflectance at
these shorter wavelengths.
If there is suspended sediment (S) present in the
upper layers of the water body, then this will allow
better reflectivity and a brighter appearance of the
water.
Chlorophyll in algae absorbs more of the blue
wavelengths and reflects the green, making the
water appear more green when algae is present.
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Leaves: Water
Content
 Water absorbs radiation in nearinfrared region.
 Near-infrared
reflectance
can
also provide information about
Reflectance
leaf-water content.
Infiltrating leaves with water fills the air
gaps and there is a decrease in multiple
scattering,
Wavelength
reflectance
resulting
in
decrease
NIR
© Asian Institute of Technology, 2014, All Rights Reserved
Color Composite
Color Composite:
RGB- Designed to display raster data in Red Green Blue (RGB) color space.
 True Color Composite (TCC)
 False Color Composite (FCC)
True color composite(TCC)- The True
color
composite
is
the
image
compositions with the band combination
as an ordinary human eye sees it.
False composite(FCC)- The False
color composite is an image with the
different band combination than its
natural color.
Sensor
Sensor
Monitor
Monitor
R >>>>
R
NIR >>>>
R
G >>>>
G
R >>>>
G
B >>>>
B
G >>>>
B
© Asian Institute of Technology, 2014, All Rights Reserved
Color Composite (Continued)
Data Acquired: Landsat TM
Area: Dong Payayen, Thailand
Source: Space Affairs Bureau of Thailand,
http://www.space.mict.go.th/knowledge.php?id=rs3
Color Composite (Continued)
NIR
R
R
G
G B
FCC
Color Composite
R
R
NIR
G
G B
FCC - Natural Color Composite
True Color and False Color Images
R:G:B:: 3:2:1
Selected bands from the image
NIR:R:G:: 4:3:2
Color’s in computer screen
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Reflectance of Earth Surface
Satellite Data Acquisition
80%
Water (clear)
Vegetation (green)
70%
Dry bare soil (gray-brown)
60%
Blue Green Red NearIR
1
2
3
4
Mid IR
5
Mid IR
7
TM band
Reflectance
50%
Soil
40%
30%
Vegetation
20%
10%
Water
0%
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
2,2
2,4
2,6
Wavelength (µm)
Blue water as black, since water absorbs NIR wavelength energy
© Asian Institute of Technology, 2014, All Rights Reserved
Resolutions
1.
Spatial Resolution
2.
Temporal Resolution
3.
Spectral Resolution
4.
Radiometric Resolution
© Asian Institute of Technology, 2014, All Rights Reserved
Spatial Resolution
The area on the ground
represented by each pixel,
refers to the fineness of
details visible in an image.
1m
2m
10m
20m
5m
20m
© Asian Institute of Technology, 2014, All Rights Reserved
Spatial Resolution (IKONOS pansharpened Product)
4-Meter Multispectral
1-Meter Panchromatic
1-Meter Pan-Sharpened
© Asian Institute of Technology, 2014, All Rights Reserved
Temporal Resolution
The revisit period of a satellite sensor is usually several days. Therefore the absolute
temporal resolution of a remote sensing system to image the exact same area at the
same viewing angle a second time is equal to this period.
But, because of some degree of overlap in the imaging swaths of adjacent orbits for
most satellites and the increase in this overlap with increasing latitude, some areas of
the Earth tend to be re-imaged more frequently.
© Asian Institute of Technology, 2014, All Rights Reserved
Temporal Resolution (Continued)
How often a sensor obtains imagery of a particular area (Time between Observations )
Satellite/Sensor
Temporal
Resolution
SPOT
26 Days
Landsat
16 Days
NOAA
Daily
MODIS (Terra/AQUA)
Daily
© Asian Institute of Technology, 2014, All Rights Reserved
Spectral Resolution
Spectral Resolution- the specific wavelength intervals that a sensor can record.
The finer the spectral resolution, the narrower the wavelength range for a particular
channel or band.
Black-White image  Wide Interval in
electromagetic
Spectrum
Coarse

Spectral Resolution
Color
Image
Narrow

electromagnetic
spectrum
Interval

in
Fine
Spectral Resolution
A sensor with higher spectral resolution is required for detailed distinction.
© Asian Institute of Technology, 2014, All Rights Reserved
Radiometric Resolution
 Radiometric resolution determines how fine the sensor can distinguish between objects
of similar reflection. The higher the radiometric resolution is, the better we can
distinguish between even subtle differences in reflection
Bit Depth
Resolution
Binary
Possible DN
Values
8 bit
(unsigned)
28
0-255
16 bit
(signed)
216
-32768 – 32677
16 bit
(unsigned)
216
0 – 65535
8 bit
(signed
Integer)
Floating
Point
1.0
1
1.000000
-1.5
-2
-1.500000
127
255.000000
Number
255
NDVI values normally range from -1 to +1 as
decimal values and therefore MUST be stored as
floating point.
 Value less than the minimum bit value capable of being store will be reduced to
the minimum bit value.
 Value greater than the maximum bit value capable of being store will be
reduced to the maximum bit value.
Radiometric Resolution (Continued)
For example, in 6-bit and 8-bit data, the data file values are as follows.
0
Radiometric Resolution
Digital Number Range
6-bit (IRS Pan)
0-63
8-bit (Landsat)
0-255
63
255
0
The finer the radiometric resolution of a sensor, the more sensitive it is to
detecting small differences in reflected or emitted energy.
© Asian Institute of Technology, 2014, All Rights Reserved
Histogram and Image Characteristics
0
255
© Asian Institute of Technology, 2014, All Rights Reserved
Multi-Spectral and Hyper-Spectral
Muti-spectral
5- 8 bands
Hyper-spectral
More than 100 bands
© Asian Institute of Technology, 2014, All Rights Reserved
Coarse Resolution Sensors
(Pixel Size > 100m)
© Asian Institute of Technology, 2014, All Rights Reserved
MODIS

Moderate Resolution Imaging Spectroradiometer

36 spectral bands – 12 bit resolution

Currently on TERRA or AQUA satellites

Revisit time for sensor is 1day
VISIBLE
400
89 3
SWIR
NIR
500 600 700 800 900 1000 nm
4
1
2
250m, 500m & 1000m
(Only bands 1-9 within the VNIR are shown here)
© Asian Institute of Technology, 2014, All Rights Reserved
MODIS
(Moderate Resolution Imaging Spectroradiometer)
Sees every point on our world every 1-2 days
in 36 discrete spectral bands.
Spatial Resolution
- 250m(bands 1-2)
- 500m(bands 3-7)
- 1000m(bands 8-36)
MODIS greatly improves upon the heritage of the NOAA
Advanced Very High Resolution Radiometer (AVHRR) and
tracks a wider array of the earth's vital signs than any other Terra sensor.
MODIS is ideal for monitoring large-scale changes in the biosphere
that will yield new insights into the workings of the global carbon cycle.
© Asian Institute of Technology, 2014, All Rights Reserved
Primary Use
Band
Bandwidth
Land/Cloud
1
620- 670
Boundaries
2
Land/Cloud
Properties
21
3.929- 3.989
841- 876
22
3.929- 3.989
3
459- 479
23
4.020- 4.080
4
545- 565
Atmospheric
24
4.433- 4.498
5
1230- 1250
Temperature
25
4.482- 4.549
6
1628- 1652
Cirrus Clouds
26
1.360- 1.390
7
2105- 2155
Water Vapor
27
6.535- 6.895
Ocean Color/
8
405- 420
28
7.175- 7.475
Phytoplankton/
9
438- 448
29
8.400- 8.700
Biogeochemistry
10
483- 493
Ozone
30
9.580- 9.880
11
526- 536
Surface/Cloud
31
10.780- 11.280
12
546- 556
Temperature
32
11.770- 12.270
13
662- 672
Cloud Top
33
13.185- 13.485
14
673- 683
Altitude
34
13.485- 13.785
15
743- 753
35
13.785- 14.085
16
862- 877
36
14.085- 14.385
Atmospheric
17
890- 920
Bands 1 to 19, nm; Bands 20-36, μm
Water Vapor
18
931- 941
Spatial Resolution:
19
915- 965
250 m (bands 1-2)
20
3.660- 3.840
Surface/Cloud
Temperature
500 m (bands 3-7)
250m
500m
1000 m (bands 8-36)
1km
© Asian Institute of Technology, 2014, All Rights Reserved
Medium Resolution Sensors
(5m < Pixel Size < 100m)
© Asian Institute of Technology, 2014, All Rights Reserved
LANDSAT ETM

Enhanced Thematic Mapper Plus - 8 bit

1 Panchromatic band – 15m

8 multi-spectral bands

4 visible and near infrared (VNIR) – 30m

2 SWIR – 30m

2 thermal (LWIR) – 60m
VISIBLE
400
NIR
SWIR
500 600 700 800 900 1000 nm
1
2
3
4
30 m
© Asian Institute of Technology, 2014, All Rights Reserved
LANDSAT ETM (Continued)

Data Archive = $600 per scene or ~ $0.04 per km2

Sites

http://landsat.gsfc.nasa.gov/

http://edcdaac.usgs.gov/main.html

http://glcfapp.umiacs.umd.edu:8080/esdi/index.jsp (Free download)
© Asian Institute of Technology, 2014, All Rights Reserved
ASTER (In TERRA Satellite)

Advanced Spaceborne Thermal Emission and Reflection Radiometer

Currently on TERRA satellite1
VISIBLE
NIR
SWIR
400 500 600 700 800 900 1000 nm
1
2
3
15 m
© Asian Institute of Technology, 2014, All Rights Reserved
ASTER Characteristics

3 channels of VNIR

6 channels of SWIR

5 channels of TIR

Capable of stereoscopic imagery

Channel 3 contains 25 meter “overlap”

Free to NASA researchers or $55 a scene

Sites

http://asterweb.jpl.nasa.gov/

http://edcdaac.usgs.gov/main.html
© Asian Institute of Technology, 2014, All Rights Reserved
High Resolution Sensors
(Pixel Size < 5m)
© Asian Institute of Technology, 2014, All Rights Reserved
IKONOS

Launched 1999

1 Panchromatic band – 1m

4 Multispectral bands – 4m

Request = $30 per km2

Archive = $15 per km2
VISIBLE
400
NIR
SWIR
500 600 700 800 900 1000 nm
1
2
3
4
Source: http://www.spaceimaging.com/
1m
© Asian Institute of Technology, 2014, All Rights Reserved
Quickbird

Launched 2001

Highest resolution satellite currently available

1 Panchromatic band – 61cm

4 Multispectral bands – 2.8 m

Request = $30 per km2
VISIBLE
NIR
SWIR
400 500 600 700 800 900 1000 nm
1
2
Source: http://digitalglobe.com/
3
4
61 cm
© Asian Institute of Technology, 2014, All Rights Reserved
Remote Sensing for Coastal Zone Management
Shrimp Farm extension in Chantaburi (1987- 1995)
February 1987:LandSat-TM
August 1997: ADEOS-AVNIR
Extent of shrimp cultivation increase within ten years period in Chantaburi coastal area is
clearly visible. Area shown within yellow square/circle in 1997 image are the area converted to
shrimp farms.
© Asian Institute of Technology, 2014, All Rights Reserved
June 2001
January, 2005
About 80 km south of Banda Aceh, Indonesia, coastal villages were destroyed by the December tsunami. The images
are located near latitude 4.8 degrees north and longitude 95.4 east. They cover an area of about 14.3 x 9.1 km.
Credit Source: NASA/GSFC/METI/Japan Space Systems, and U.S./Japan ASTER Science Team
© Asian Institute of Technology, 2014, All Rights Reserved
View of Seasonal Change of Tonle Sap Lake
by Terra MODIS of 250 m resolution
10 Jan 2002
09 Apr 2002
07 Jul 2002
11 Oct 2002
© Asian Institute of Technology, 2014, All Rights Reserved
Bangladesh from
MODIS
This view of Bangladesh shows the
confluence of the Padma (Ganges)
and
Jamuna
empty
Rivers
before
they
into
the
Bay
of
Bengal.
(Resolution:
625
meters;
MODIS
MODIS-PFM;
MODIS
Data
Type:
Band Combination: 1, 4, 3)
Credit: Jacques Descloitres, MODIS
Land Science Team
© Asian Institute of Technology, 2014, All Rights Reserved
Mouth of the Yellow
River, China
A MODIS view of sediment emerging
from the mouth of the Yellow River in
China
Credit: Jacques Descloitres, MODIS
Land Group, 02-28-2000
© Asian Institute of Technology, 2014, All Rights Reserved