High-Resolution Optical Imagers
Description
High-resolution optical imagers provide
detailed images of Earth’s surface. In
general, these are nadir-viewing instruments
with a horizontal spatial resolution in the
range 10 m to 100 m and swath widths of
order 100 km. In the past few years,
high-resolution sensors have emerged with
spatial resolution in the range 1 m to 5 m.
An increasing number of government-funded
and private sector-funded sensors with sub-5
m resolution are planned for the coming
years.
High-resolution imagers are, in general,
panchromatic (a single waveband) and
multi-spectral (multiple waveband) sensors,
with spectral bands in the visible and IR
range that are simultaneously recorded. This
increases the information content that may
be derived from the imagery (including the
ability for land cover classification) and
allows corrections to be made, for example,
for the effects of atmospheric water vapour
on the measured surface parameters. In order
to reduce atmospheric absorption and to
increase image quality, the operating
wavelengths of these instruments are
selected to coincide with atmospheric
windows.
Use of these sensors can be limited by
weather conditions, since they are unable to
penetrate thick cloud, rain or fog and are
typically restricted to fair weather,
daytime-only operation. Some have pointing
capability which enables imagery of
specified areas to be acquired more
frequently.
Many countries, including developing
countries, have and/or are planning
high-resolution optical imaging missions.
Future trends will include a greater number
of sampling channels, as well as improved
spectral and spatial resolution. More
instruments will also become available that
are capable of producing stereo images from
data collected on a single orbit, i.e.
along-track, as opposed to across-track, so
that stereo images can be acquired from
different passes.
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Current & planned
instruments
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AEISS
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MSU-200
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AEISS-A
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MUX (SJ-9A)
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ALI
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NigeriaSat Medium and High
Resolution
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ASTER
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PAN
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ATCOR
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PAN (Cartosat-1)
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BGIS 2000
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PAN (Cartosat-2)
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CCD (HJ)
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PAN
(Cartosat-2A/2B)
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Event Imaging Spectrometer from
GEO (GeoCape)
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PAN
(Cartosat-2C/2E)
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Geoton-L1
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PAN
(Cartosat-3)
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HiRI
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PAN (CBERS)
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HISUI
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PAN (FORMOSAT)
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HRG
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PAN (GISTDA)
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HRS
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PAN (SJ-9A)
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LISS-III (Resourcesat)
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PAN (ZY-02C)
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LISS-IV
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PAN CAMERA
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MSC
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PAN+MS (RGB+NIR)
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MSI
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PRISM-2 (ALOS-3)
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MSI (Sentinel-2)
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PSS
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MSS (Kanonpus)
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SLIM-6-22
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MSS (Sich)
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VHR PAN Camera and MS Camera
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Applications
High-resolution optical imagers are amongst
the most common Earth observation satellite
instruments, finding application in, for
example:
— Agriculture, including definition of crop
type and area, crop inventory, yield
prediction and crop stress identification;
— Damage assessment associated with natural
hazards;
— Geological mapping;
— Urban planning, including land cover
mapping, topographic mapping and urban
development monitoring;
— Cartography, including map generation and
updating, generation of digital elevation
models;
— Environmental planning and monitoring.
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