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PRISM, Panchromatic Remote-sensing Instrument for Stereo Mapping, is a panchromatic radiometer on board the ALOS satellite mission, launched in 2006. The radiometer has 2.5m spatial resolution at nadir and its extracted data provides digital surface models.
PRISM has three independent optical systems for viewing nadir, forward, and backward, producing a stereoscopic image along the satellite’s track. The nadir-viewing telescope covers a width of 70 km, and the forward and backward viewing telescopes each cover 35 km.
Table 5: AVNIR-2 Sensor Characteristics Number of Bands 4
Wavelength Band 1: 0.42 to 0.50 μm Band 2: 0.52 to 0.60 μm Band 3: 0.61 to 0.69 μm Band 4: 0.76 to 0.89 μm Spatial Resolution 10 m (at Nadir)
Swath Width 70 km (at Nadir) Number of Detectors 7000 per band Pointing Angle - 44 to + 44 degrees
Bit Length 8 bits
PRISM’s wide field of view (FOV) provides three fully overlapped stereo images of a 35 km width without mechanical scanning or yaw steering of the satellite.
Source: Japan Aerospace Exploration Agency, 2003c.
ASTER
ASTER (Advanced Spaceborne Thermal Emission and ReflectionRadiometer) is an instrument flying on Terra, a satellite launched in December 1999 as part of NASA’s Earth Observing System (EOS).
ASTER is a cooperative effort between NASA, Japan’s Ministry of Economy, Trade and Industry (METI), and Japan’s Earth Remote Sensing Data Analysis Center (ERSDAC). Compared with the Landsat Thematic Mapper and Japan’s JERS-1 OPS scanner, the ASTER instrument is the next generation in remote sensing imaging.
ASTER captures high resolution data in the visible to thermal infrared wavelength spectrum and provides stereo viewing capability for DEM creation.
The ASTER instrument consists of three subsystems: Visible and Near Infrared (VNIR), Shortwave Infrared (SWIR), and Thermal Infrared (TIR).
Table 6: PRISM Sensor Characteristics Number of Bands 1 (panchromatic)
Wavelength 0.52 to 0.77 μm
Number of Optics 3 (Nadir, Forward, Backward)
Base-to-Height Ratio 1.0 (between Forward and Backward view) Spatial Resolution 2.5 m (at Nadir)
Source: National Aeronautics and Space Administration, 2004.
EROS A and EROS B
The first Earth Remote Observation Satellite (EROS A), launched in December 2000, was developed by ImageSat International N.V. They subsequently launched their second satellite, EROS B, in April 2006.ImageSat International N.V. is a Netherlands Antilles company with offices in Cyprus and Israel.
EROS A imaging techniques offer panchromatic images in basic type and as stereo pairs. EROS B imaging techniques offer panchromatic images in basic, stereo pair, triplet, and mosaic types.
Source: ImageSat International N.V. 2008
FORMOSAT-2
The FORMOSAT-2 satellite, launched in May 2004, was the first remote sensing satellite developed by National Space Organization (NSPO). The main mission of FORMOSAT-2 is to capture satellite images of Taiwan island and surrounding oceanic regions, and terrestrial and oceanic regions of the entire Earth.Band 3
Table 8: EROS A - EROS B Characteristics
Characteristic EROS A EROS B
Geometry of orbit sun-synchronous sun-synchronous
Orbit Altitude ~ 500 km ~ 500 km
Swath Width 14 km at nadir 7 km at nadir Ground Sampling Spectral Bandwidth 0.5 to 0.9 0.5 to 0.9
FORMOSAT-2 onboard sensors include a Remote Sensing Instrument and ISUAL (Imager of Sprites and Upper Atmospheric Lightning).
Source: National Space Organization, 2008 and European Space Agency, 2010b.
GeoEye-1
The GeoEye-1 satellite, launched in 2008, was developed by GeoEye, a company formed through the combination of ORBIMAGE and Space Imaging. GeoEye-1 orbits at an altitude of 681 km, or 423 miles in a sun-synchronous orbit type.GeoEye-1 data collection capacity is up to 700,000 square km per day of pan area and up to 350,000 square km per day of pan-sharpened multispectral area.
Table 9: FORMOSAT-2 Characteristics Geometry of orbit sun-synchronous
Orbit Altitude 891 km
Swath Width 24 km
Sensor Resolution panchromatic - 2 m multispectral - 8 m
Table 10: GeoEye-1 Characteristics Geometry of orbit sun-synchronous
Orbit Altitude 681 km Orbit Inclination 98 degrees Swath Width 15.2 km at nadir
Area Size - single point 225 sq km (15 km x 15 km) Area Size - large area 15,000 sq km (300 km x 50 km) Area Size - cell size 10,000 sq km (100 km x 100 km) Area Size - stereo area 6,270 sq km (224 km x 28 km) Sensor Resolution
nominal at Nadir
panchromatic - 0.41 m (1.34 feet) multispectral - 1.65 m (5.41 feet) Spectral Bandwidth
Panchromatic
459 to 800 nm
Source: GeoEye, 2008.
IKONOS
The IKONOS satellite was launched in September 1999.The resolution of the panchromatic sensor is 1 m. The resolution of the multispectral scanner is 4 m. The swath width is 13 km at nadir. The accuracy with out ground control is 12 m horizontally, and 10 m vertically; with ground control it is 2 m horizontally, and 3 m vertically.
IKONOS orbits at an altitude of 423 miles, or 681 kilometers. The revisit time is 2.9 days at 1 m resolution, and 1.5 days at 1.5 m resolution.
Source: Space Imaging, 1999a; Center for Health Applications of Aerospace Related Technologies, 2000a
IRS
IRS-1C
The IRS-1C satellite was launched in December of 1995.
The repeat coverage of IRS-1C is every 24 days. The sensor has a 744 km swath width.
The IRS-1C satellite has three sensors on board with which to capture images of the Earth. Those sensors are as follows:
LISS-III
LISS-III has a spatial resolution of 23 m, with the exception of the SW Infrared band, which is 70 m. Bands 2, 3, and 4 have a swath width of 142 kilometers; band 5 has a swath width of 148 km. Repeat coverage occurs every 24 days at the Equator.
Spectral Bandwidth Multispectral
450 - 510 nm (blue) 510 - 580 nm (green) 655 - 690 nm (red) 780 - 920 (near infrared) Table 10: GeoEye-1 Characteristics
Band Wavelength (microns)
1, Blue 0.45 to 0.52 μm
2, Green 0.52 to 0.60 μm
3, Red 0.63 to 0.69 μm
4, NIR 0.76 to 0.90 μm
Panchromatic 0.45 to 0.90 μm
Source: National Remote Sensing Agency, 1998 Panchromatic Sensor
The panchromatic sensor has 5.8 m spatial resolution, as well as stereo capability. Its swath width is 70 m. Repeat coverage is every 24 days at the Equator. The revisit time is every five days, with ± 26° off-nadir viewing.
Wide Field Sensor (WiFS)
WiFS has a 188 m spatial resolution, and repeat coverage every five days at the Equator. The swath width is 774 km.
Source: Space Imaging, 1999b; Center for Health Applications of Aerospace Related Technologies, 1998
IRS-1D
IRS-1D was launched in September of 1997. It collects imagery at a spatial resolution of 5.8 m. IRS-1D’s sensors were copied for IRS-1C, which was launched in December 1995.
Band Wavelength (microns)
1, Blue
---2, Green 0.52 to 0.59 μm
3, Red 0.62 to 0.68 μm
4, NIR 0.77 to 0.86 μm
5, SW IR 1.55 to 1.70 μm
Band Wavelength (microns)
Pan 0.5 to 0.75 μm
Band Wavelength (microns)
1, Red 0.62 to 0.68 μm
2, NIR 0.77 to 0.86 μm
3, MIR 1.55 to 1.75 μm
Imagery collected by IRS-1D is distributed in black and white format.
The panchromatic imagery “reveals objects on the Earth’s surface (such) as transportation networks, large ships, parks and opens space, and built-up urban areas” (Space Imaging, 1999b). This information can be used to classify land cover in applications such as urban planning and agriculture. The Space Imaging facility located in Norman, Oklahoma has been obtaining IRS-1D data since 1997.
For band and wavelength data on IRS-1D, see IRS on page 73.
Source: Space Imaging, 1998
KOMPSAT 1-2
Korea Aerospace Research Institute (KARI) has developed the KOMPSAT-1 (KOrea Multi-Purpose SATellite) and KOMPSAT-2 satellite systems for surveillance of large scale disasters, acquisition of high resolution images for GIS, and composition of printed and digitized maps.KOMPSAT-1, launched in December 1999, carries an Electro-Optical Camera (EOC) sensor and KOMPSAT-2, launched in July 2006, carries a Multi-Spectral Camera (MSC) sensor.
Through a third party mission agreement, European Space Agency makes a sample dataset of European cities available from these missions.
Source: European Space Agency, 2010c
Table 11: KOMPSAT-1 and KOMPSAT-2 Characteristics Characteristic KOMPSAT-1 KOMPSAT-2
Geometry of orbit sun-synchronous circular polar
sun-synchronous circular
Orbit Altitude 685 km 685 km
Swath Width 24 km EOC ~ 15 km
Resolution 6 m EOC 1 m panchromatic
4 m multispectral
Spectral Bandwidth 500 - 900 nm
panchromatic 450 - 900 nm
multispectral (4 bands)
Landsat 1-5
In 1972, the National Aeronautics and Space Administration (NASA) initiated the first civilian program specializing in the acquisition of remotely sensed digital satellite data. The first system was called ERTS (Earth Resources Technology Satellites), and later renamed toLandsat. There have been several Landsat satellites launched since 1972. Landsats 1, 2, 3 and 4 are no longer operating, but Landsat 5 is still in orbit gathering data.
Landsats 1, 2, and 3 gathered Multispectral Scanner (MSS) data and Landsats 4 and 5 collected MSS and TM data. MSS and TM are discussed in more detail in the following sections.
NOTE: Landsat data are available through the EROS Data Center. See Ordering Raster Data on page 127 for more information.
MSS
The Multispectral Scanner from Landsats 4 and 5 has a swath width of approximately 185 × 170 km from a height of approximately 900 km for Landsats 1, 2, and 3, and 705 km for Landsats 4 and 5. MSS data are widely used for general geologic studies as well as vegetation
inventories.
The spatial resolution of MSS data is 56 × 79 m, with a 79 × 79 m IFOV.
A typical scene contains approximately 2340 rows and 3240 columns.
The radiometric resolution is 6-bit, but it is stored as 8-bit (Lillesand and Kiefer, 1987).
Detectors record electromagnetic radiation (EMR) in four bands:
• Bands 1 and 2 are in the visible portion of the spectrum and are useful in detecting cultural features, such as roads. These bands also show detail in water.
• Bands 3 and 4 are in the near-infrared portion of the spectrum and can be used in land/water and vegetation discrimination.
Band Wavelength
(microns) Comments
1, Green
0.50 to 0.60
μm This band scans the region between the blue and red chlorophyll absorption bands. It corresponds to the green reflectance of healthy vegetation, and it is also useful for mapping water bodies.
2, Red 0.60 to 0.70
μm This is the red chlorophyll absorption band of healthy green vegetation and represents one of the most important bands for vegetation discrimination. It is also useful for determining soil boundary and geological boundary delineations and cultural features.
Source: Center for Health Applications of Aerospace Related Technologies, 2000b
TM
The TM scanner is a multispectral scanning system much like the MSS, except that the TM sensor records reflected/emitted electromagnetic energy from the visible, reflective-infrared, middle-infrared, and thermal-infrared regions of the spectrum. TM has higher spatial, spectral, and radiometric resolution than MSS.
TM has a swath width of approximately 185 km from a height of approximately 705 km. It is useful for vegetation type and health determination, soil moisture, snow and cloud differentiation, rock type discrimination, and so forth.
The spatial resolution of TM is 28.5 × 28.5 m for all bands except the thermal (band 6), which has a spatial resolution of 120 × 120 m. The larger pixel size of this band is necessary for adequate signal strength.
However, the thermal band is resampled to 28.5 × 28.5 m to match the other bands. The radiometric resolution is 8-bit, meaning that each pixel has a possible range of data values from 0 to 255.
Detectors record EMR in seven bands:
• Bands 1, 2, and 3 are in the visible portion of the spectrum and are useful in detecting cultural features such as roads. These bands also show detail in water.
• Bands 4, 5, and 7 are in the reflective-infrared portion of the spectrum and can be used in land/water discrimination.
• Band 6 is in the thermal portion of the spectrum and is used for thermal mapping (Jensen, 1996; Lillesand and Kiefer, 1987).
3, Red,
NIR
0.70 to 0.80
μm This band is especially responsive to the amount of vegetation biomass present in a scene. It is useful for crop identification and emphasizes soil/crop and land/water contrasts.
4, NIR 0.80 to 1.10
μm This band is useful for vegetation surveys and for penetrating haze (Jensen, 1996).
Band Wavelength
(microns) Comments
Source: Center for Health Applications of Aerospace Related Technologies, 2000b
Band Wavelength
(microns) Comments
1, Blue 0.45 to 0.52
μm This band is useful for mapping coastal water areas, differentiating between soil and
vegetation, forest type mapping, and detecting cultural features.
2, Green
0.52 to 0.60
μm This band corresponds to the green reflectance of healthy vegetation. Also useful for cultural feature identification.
3, Red 0.63 to 0.69
μm This band is useful for discriminating between many plant species. It is also useful for determining soil boundary and geological boundary delineations as well as cultural features.
4, NIR 0.76 to 0.90
μm This band is especially responsive to the amount of vegetation biomass present in a scene. It is useful for crop identification and emphasizes soil/crop and land/water contrasts.
5, MIR 1.55 to 1.75
μm This band is sensitive to the amount of water in plants, which is useful in crop drought studies and in plant health analyses. This is also one of the few bands that can be used to discriminate between clouds, snow, and ice.
6, TIR 10.40 to 12.50
μm This band is useful for vegetation and crop stress detection, heat intensity, insecticide applications, and for locating thermal pollution.
It can also be used to locate geothermal activity.
7, MIR 2.08 to 2.35
μm This band is important for the discrimination of geologic rock type and soil boundaries, as well as soil and vegetation moisture content.
Figure 24: Landsat MSS vs. Landsat TM
Band Combinations for Displaying TM Data
Different combinations of the TM bands can be displayed to create different composite effects. The following combinations are commonly used to display images:
NOTE: The order of the bands corresponds to the Red, Green, and Blue (RGB) color guns of the monitor.
• Bands 3, 2, 1 create a true color composite. True color means that objects look as they would to the naked eye—similar to a color photograph.
• Bands 4, 3, 2 create a false color composite. False color composites appear similar to an infrared photograph where objects do not have the same colors or contrasts as they would naturally. For instance, in an infrared image, vegetation appears red, water appears navy or black, and so forth.
• Bands 5, 4, 2 create a pseudo color composite. (A thematic image is also a pseudo color image.) In pseudo color, the colors do not reflect the features in natural colors. For instance, roads may be red, water yellow, and vegetation blue.
Different color schemes can be used to bring out or enhance the features under study. These are by no means all of the useful combinations of these seven bands. The bands to be used are determined by the particular application.
4 bands
7 bands
1 pixel=
30x30m 1 pixel=
57x79m
MSS
TM
radiometric resolution
0-127
radiometric resolution 0-255
See "Image Display" on page 145 for more information on how images are displayed, "Enhancement" on page 455 for more information on how images can be enhanced, and Ordering Raster Data on page 127 for information on types of Landsat data available.
Landsat 7
The Landsat 7 satellite, launched in 1999, uses Enhanced Thematic Mapper Plus (ETM+) to observe the Earth. The capabilities new to Landsat 7 include the following:• 15m spatial resolution panchromatic band
• 5% radiometric calibration with full aperture
• 60m spatial resolution thermal IR channel
The primary receiving station for Landsat 7 data is located in Sioux Falls, South Dakota at the USGS EROS Data Center (EDC). ETM+
data is transmitted using X-band direct downlink at a rate of 150 Mbps.
Landsat 7 is capable of capturing scenes without cloud obstruction, and the receiving stations can obtain this data in real time using the X-band.
Stations located around the globe, however, are only able to receive data for the portion of the ETM+ ground track where the satellite can be seen by the receiving station.