Transcript Remote Sensing from Space

Remote Sensing Media
• Aircraft Based
– photography (BW, Color), infrared (BW, Color)
– RADAR (SLAR, SAR)
– LIDAR (light detection and ranging)
• Satellite Based
– SPOT
– LandSat
– NOAA/AVHRR
– GOES
Airborne Remote Sensing ?
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Airborne remote sensing is not an efficient tool suitable for
such monitoring for many reasons.
First, airborne sensors can only provide a relatively local
view.
Each acquisition of data using an airborne system requires
an active decision to fly the instrument over the target
area.
It is extremely difficult to accurately reproduce flight lines,
which dramatically increases the difficulty of analysing and
interpreting the monitoring data.
Airborne instruments suffer through flight stresses each
time that the instrument is flown, which can compound the
difficulty of comparing data acquired at different times.
The operating expenses for an airborne instrument are
very high
Sensors And Platforms
Platforms
In order for a sensor to collect and record energy
reflected or emitted from a target or surface, it must
reside on a stable platform removed from the target or
surface being observed.
Platforms for remote sensors may be situated on the
ground, on an aircraft or balloon (or some other platform
within the Earth's atmosphere), or on a spacecraft or
satellite outside of the Earth's atmosphere.
Groundbased Platform
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Often used to record
detailed information
about the surface which
is compared with
information collected from
aircraft or satellite
sensors
Sensors may be placed
on a ladder, scaffolding,
tall building, crane, etc
Aerial Platform
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Aircraft are often
used to collect very
detailed images and
facilitate the collection
of data over virtually
any portion of the
Earth's surface at any
time
Satellite Platform
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satellites permit
repetitive coverage of
the Earth's surface on
a continuing basis.
Cost is often a
significant factor in
choosing among the
various platform
options.
Satellite Characteristics: Orbits
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The path followed by a satellite is referred to as
its orbit. Satellite orbits are matched to the
capability and objective of the sensor(s) they
carry. Orbit selection can vary in terms of
altitude (their height above the Earth's surface)
and their orientation and rotation relative to the
Earth
Orbits : GOES
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geostationary satellites, at
altitudes of approximately
36,000 kilometres, revolve at
speeds which match the
rotation of the Earth so they
seem stationary, relative to the
Earth's surface
This allows the satellites to
observe and collect
information continuously over
specific areas
Orbits : Near POES
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named for the inclination
of the orbit relative to a
line running between the
North and South poles
Many of these satellite
orbits are also sunsynchronous such that
they cover each area of
the world at a constant
local time of day called
local sun time.
Satellite Characteristics: Swath
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As a satellite revolves
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
Imaging swaths for
spaceborne sensors
generally vary between
tens and hundreds of
kilometres wide
Swath
SPOT
• Developed by France, launched in 1986
• Provides full stereoscopic imaging
• Three spectral bands
– .5-.59, .61-.68, .79-.89
• Ground Resolution
– 20m multi-spectral
– 10m panchromatic
• Uses
– geologic exploration, regional planning
Landsat
• Developed by NASA in mid-1960’s
• Two sensors
– Return Beam Vidicon - similar to a TV camera
– Multispectral Scanner (MSS)
• Landsat 4 and 5 introduced Thematic Mapper
(TM)
– higher spatial resolution than MSS. Data in 7 bands
instead of 4
ERTS-1
• First Unmanned Satellite Dedicated to
Multi-Spectral Remote Sensing
• Renamed Landsat
– The RBV (Return Beam Vidicon) consisted of
three TV-like cameras which used color
filters to provide multispectral bands
• MSS (Multi-Spectral Scanner)
Malaysian satellite (TiungSat)
Faculty of Geoinformation Science and Engineering
Universiti Teknologi Malaysia
81310 UTM Skudai. Johor Bahru
http://www.fksg.utm.my
Orbit Types
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Geostationary (Met satellites)
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Meteosat (Europe)
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GOES (US)
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GMS (Japan)
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INSAT (India)
Polar Orbiting
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Landsat (US)
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SPOT (France)
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NOAA (US)
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ERS-1, -2 (Europe)
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Radarsat (Canada)
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JERS (Japan)
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Envisat (Europe)
Faculty of Geoinformation Science and Engineering
Universiti Teknologi Malaysia
81310 UTM Skudai. Johor Bahru
http://www.fksg.utm.my
Orbits Types
Orbits
geostationary (36 000 km
altitude)
polar orbiting (200-1000 km
altitude)
Spatial resolution
10s cm (??) - 100s km
determined by altitude of satellite
(across track), altitude and
speed (along track), viewing
angle
Temporal Resolution
minutes to days
NOAA (AVHRR), 12 hrs, 1km
(1978+)
Landsat TM, 16 days, 30 m
(1972+)
SPOT, 26(...) days, 10-20 m
(1986+)
revisit depends on
latitude
sensor FOV, pointing
orbit (inclination, altitude)
cloud cover (for optical
instruments)
View from satellite ( Ikonos )
KLCC
Setulang laut free duty area