Richards J.A., Jia X. Remote Sensing Digital Image Analysis: An Introduction

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A.2 Earth Resource Satellite Sensors in the Visible and Infrared Regions 395

Table A.7. Characteristics of the Landsat imaging devices

Instrument Spectral bands IFOV Dynamic range

(

µm) (m) (bits)

RBV

1. 0.475– 0.575 (blue) 79 × 79

2. 0.580– 0.680 (red) 79 × 79

3. 0.689– 0.830 (near IR) 79 × 79

RBV

0.505– 0.750 (panchromatic) 40 × 40

MSS 4.

0.5 – 0.6 (green) 79 × 79 7

5. 0.6 – 0.7 (red) 79 × 79 7

6. 0.7 – 0.8 (near IR) 79 × 79 7

7. 0.8 – 1.1 (near IR) 79 × 79 6

10.4 –12.6 (thermal) 237 × 237

TM 1. 0.45 – 0.52 (blue) 30 × 30 8

2. 0.52 – 0.60 (green) 30 × 30 8

3. 0.63 – 0.69 (red) 30 × 30 8

4. 0.76 – 0.90 (near IR) 30 × 30 8

5. 1.55 – 1.75 (mid IR) 30 × 30 8

2.08 – 2.35 (mid IR) 30 × 30 8

6. 10.4 –12.5 (thermal) 120 × 120 8

ETM+ 1. 0.450– 0.515 (blue) 30 × 30 8

2. 0.525– 0.605 (green) 30 × 30 8

3. 0.630– 0.690 (red) 30 × 30 8

4. 0.775– 0.900 (near IR) 30 × 30 8

5. 1.550– 1.750 (mid IR) 30 × 30 8

7. 2.090– 2.350 (mid IR) 30 × 30 8

6. 10.40 –12.50 (thermal) 60 × 60 8

pan 0.520– 0.900 13 × 15 8

MSS bands 4 to 7 have been renumbered MSS bands 1 to 4 from Landsat 4 onwards.

IFOV = 81.5, 82.5 m for Landsats 4, 5.

MSS band 8 was used only on Landsat 3.

TM band 7 is out of sequence since it was added last in the design after the previous six bands

had been ﬁrmly established. It was incorporated at the request of the geological community

owing to the importance of the 2 µm region in assessing hydrothermal alteration.

electrical signal corresponding to the energy received along the 79 m wide associated

scan line. The optical aperture of the MSS and its detectors for bands 4 to 7 is such

that at any instant of time each detector sees a pixel that is 79 m in size also along the

scan line. Consequently the effective pixel size (or instantaneous ﬁeld of view IFOV)

of the detectors is 79 m × 79 m. At a given instant the output from a detector is the

integrated response from all cover types present in a 79 m×79 m region of the earth’s

surface. Without any further processing the signal from the detector would appear to

be varying continuously with time. However it is sampled in time to produce discrete

measurements across a scan line. The sampling rate corresponds to pixel centres of

56 m giving a 23 m overlap of the 79 m × 79 m pixels, as depicted in Fig. A.2. The

thermal infrared band on Landsat 3, band 8, has an IFOV of 239 m × 239 m. As a

396 A Missions and Sensors

Fig. A.2. The relationship between instantaneous ﬁeld of view and pixel overlap for Landsat

MSS pixels

result there are only two band 8 scan lines corresponding to the six for bands 4 to 7,

as indicated above.

The IFOV’s of the multispectral scanners on Landsats 4 and 5 have been modiﬁed

to 81.5 m and 82.5 m respectively although the pixel centre spacing of 56 m has

been retained. In addition the bands have been renamed as bands 1, 2, 3 and 4,

corresponding to bands 4, 5, 6 and 7 from the earlier missions.

After being spatially sampled, the data from the detectors is digitised in amplitude

into 6 bit words. Before so-encoding, the data for bands 4, 5 and 6 is compressed

allowing decompression into effective 7 bit words upon reception at a ground station.

A.2.5

The Thematic Mapper (TM)

and Enhanced Thematic Mapper + (ETM+)

The Thematic Mapper is a mechanical scanning device as for the MSS, but has

improved spectral, spatial and radiometric characteristics. Seven wavelength bands

are used, with coverage as shown in Table A.7. Note that band 7 is out of place in the

progression of wavelengths, it having been added, after the initial planning phase, at

the request of the geological community. The Enhanced Thematic Mapper + carried

on Landsat 7 includes a panchromatic band and improved spatial resolution on the

thermal band.

Whereas the MSS of all Landsats scans and obtains data in one direction only,

the TM acquires data in both scan directions again with a swath width of 185 km.

Sixteen scan lines are swept simultaneously giving a 480 m strip across the satellite

path, as illustrated in Fig. A.3. This permits a lower mirror scan rate compared with

the MSS and thus gives a higher effective dwell time for a given spot on the ground,

making possible the higher spatial resolution and improved dynamic range.

A.2 Earth Resource Satellite Sensors in the Visible and Infrared Regions 397

Fig. A.3. Scanning characteristics of the Landsat Thematic Mapper

A.2.6

The SPOT HRV, HRVIR, HRG, HRS and Vegetation Instruments

The early French SPOT satellites (Système pour d’Observation de la Terre), carried

two imaging devices referred to as HRV’s. These instruments utilize a different

technology for image acquisition from that employed in the Landsat MSS and TM

devices. Rather than using oscillating mirrors to provide cross-track scanning during

the forward motion of the space platform, the SPOT HRV instruments consist of a

linear array of charge coupled device (CCD) detectors. These form what is commonly

referred to as a “push broom” scanner. Each detector in the array scans a strip in the

along track direction. By having several thousand such detectors a wide swath can

be imaged without the need for mechanical scanning. Moreover, owing to the long

effective dwell time this allows for each pixel, a higher spatial resolution is possible.

A trade-off however is that charge coupled device technology was not available for

wavelengths into the middle infrared range at the time of early SPOT development.

Consequently the spectral bands provided by the HRV are not unlike those of the

Landsat MSS.

The HRV covers a ground swath width of 60 km; two instruments are mounted

side by side in the spacecraft to give a total swath width of 117 km, there being a

3km overlap of the individual swaths.

Two imaging modes are possible. One is a multispectral mode and the other

panchromatic. The imaging characteristics of these are summarised, along with the

satellite orbital properties, in Table A.8.

An interesting property of the HRV is that it incorporates a steerable mirror to

allow imaging to either side of nadir. This allows daily coverage for a short period

along with a stereoscopic viewing capability.

SPOT 4, launched in March 1998, carries two instruments – the HRVIR (High

Resolution Visible and Infrared) and the Vegetation instrument. Characteristics of

both are summarised in Table A.8.

SPOT 5 carries an instrument known as HRG (High Resolution Geometry) that

uses essentially the same wavebands as the HRVIR but with a higher spatial res-

olution. Its characteristics are also summarised in Table A.8. SPOT 5 also carries

the Vegetation instrument, along with a new device called the HRS (High Resolution

398 A Missions and Sensors

Table A.8. Spot satellite and sensor characteristics

multispectral mode

panchromatic mode

Stereoscopy) that images fore and aft of the spacecraft to allow stereoscopic products

to be developed.

A.2.7

ADEOS (Advanced Earth Observing Satellite)

ADEOS-I was launched by the Japanese space agency NASDA in August 1996. It

carried a number of imaging instruments and non-imaging sensors, including OCTS

(Ocean Colour and Temperature Sensor), AVNIR (Advanced Visible and Near In-

frared Radiometer), NSCAT (NASA Spectrometer), TOMS (Total Ozone Mapping

Spectrometer), POLDER (Polarization and Directionality of the Earth’s Reﬂectance),

A.2 Earth Resource Satellite Sensors in the Visible and Infrared Regions 399

Table A.9. ADEOS satellite and sensor characteristics

IMG (lnterferometric Monitor for Greenhouse Gases), ILAS (Improved Limb At-

mospheric Sensor) and RIS (Retroreﬂector in Space). Its successor, ADEOS-II,

was launched on 14 December 2002. The sensors on ADEOS-II (now also called

MIDORI-II) are the GLI (Global Imager), AMSR (Advanced Microwave Scanning

Radiometer), ILAS-II, POLDER and SeaWINDS.

Characteristics of the OCTS, GLI and AVNIR are given in Table A.9, along with

spacecraft orbital details.

A.2.8

Sea-Viewing Wide Field of View Sensor (SeaWiFS)

In August 1997 the OrbView-2 (SeaStar) satellite was launched, carrying the Sea-

WiFS sensor with characteristics as shown in Table A.10. Its wavebands have been

chosen with ocean-related applications in mind.

400 A Missions and Sensors

Table A.10. SeaStar satellite and SeaWiFS sensor characteristics

Table A.11. MOS orbit and sensor characteristics

A.2.9

Marine Observation Satellite (MOS)

The Marine Observation Satellites MOS-l and MOS-lb were launched by Japan in

February 1987 and February 1990 respectively and were taken out of service in March

1995 and April 1996 respectively. While intended largely for oceanographic studies,

the data from the satellites’two optical imaging sensors – the MESSR (Multispectrum

Electronic Self Scanning Radiometer) and the VTIR (Visible and Thermal Infrared

A.2 Earth Resource Satellite Sensors in the Visible and Infrared Regions 401

Radiometer) are of value to land based remote sensing as well. The satellites also

carried a Microwave Scanning Radiometer (MSR) intended for water vapour, snow

and ice studies. Two MESSRs were used to provide side by side observations. Each

has a 100 km swath width; with an overlap in coverage of 15 km the total available

swath is 185 km.

Orbital details of the MOS satellites and characteristics of their optical sensors

are given in Table A.11.

A.2.10

Indian Remote Sensing Satellite (IRS)

A series of remote sensing satellites has been launched by India since March 1988.

They carry imaging systems known as the LISS (Linear Imaging Self Scanner),

the WiFS (Wide Field Sensor), the advanced version AWiFS, the Ocean Colour

Monitor (OCM), the Multifrequency Scanning Microwave Radiometer (MSMR), the

Molecular Optoelectronic Scanner (MOS) and a panchromatic sensor. Orbital details

of the satellites and characteristics of the sensors are summarised in Table A.12.

A.2.11

RESURS-O1

Russia has orbited a series of remote sensing satellites since 1985 under the name

RESURS-O1. Table A.13 gives platform and sensor characteristics for the third in the

series. The principal sensor, from which commercially available imagery is produced,

is the MSU-SK, which is a conically scanning instrument.

A.2.12

The Earth Observing 1 (EO-1) Mission

EO-1 was launched on 21 November 2000 into the same orbit as Landsat 7, but one

minute behind, allowing near simultaneous, partly overlapping coverage. The Terra

platform (see Sect.A.2.13) is essentially also in the same orbit, but 30 minutes behind

EO-1. The two imaging instruments of importance on EO-1 are the Advanced Land

Imager (ALI) and Hyperion, the characteristics of which are given in Table A.14.

A.2.13

Aqua and Terra

TheAqua and Terra platforms are part of NASA’s Earth Observing System. They were

launched respectively on 4 May 2002 and 18 December 1999 in sun synchronous

orbits comparable to those for Landsat 7, but with descending equatorial crossings

of 1:30 am (or 1:30 pm ascending) for Aqua and around 10:30 am for Terra. They

are also known as the Earth Observing System (EOS) PM (Aqua) and EOS AM

platforms (Terra).

402 A Missions and Sensors

Table A.12. IRS satellite and sensor characteristics

Orbit: Near polar, sun synchronous; nominal 10.35 am

equatorial crossing

Altitude: 904 km (1A, 1B), 817 km (1C), 736/825 km (1D)

Period: 101 min

Repeat Cycle: 22 days (1A, 1B), 24 days (1C, 1D)

Satellite imaging Instrument Launched Out-of-Service

IRS-1A LISSI Mar 1988

IRS-1B LISSII Aug1991

IRS-P2 LISSIII 16 Oct 1994

IRS-1C LISSIII, WiFS

IRS-1D LISSIII, Pan WiFS 29 Sep 1997

IRS-P3 WiFS, MOS 21 Mar 1996

IRS-P4 OCM, MSMR May 1999 (Oceansat 1)

IRS-P5 Pan Scheduled 2004 (Cartosat 1)

IRS-P6 LISSIII, LISS IV, AWiFS 17 Oct 2003 (Resourcesat 1)

Instrument Spectral bands IFOV Swath Dynamic range

(

µm) (m) (km) (bits)

LISSI, II 0.45 – 0.52 73 ×73 (LISSI) 146 7

0.52 – 0.59 36 ×36 (LISSII) 146 7

0.62 – 0.68 146 7

0.77 – 0.86

⎫

⎪

⎬

⎪

⎭

146 7

LISSIII 0.52 – 0.59 23 × 23 142 – 146 7

0.62 – 0.68 23 ×23 142 – 146 7

0.77 – 0.86 23 ×23 142 – 146 7

1.55 – 0.59 70 ×70 142 – 146 7

Pan 0.5 – 0.57 10 ×10 70 7

WiFS 0.62 – 0.68 188 × 188 774 7

0.77 – 0.86 188 ×188 774 7

LISSIV 0.53 – 0.59 5.8 × 5.8 23.9 (XS mode) 7

0.62 – 0.68 5.8 ×5.8 70.3 (Pan mode) 7

0.77 – 0.86 5.8 ×5.87

AWiFS 0.52 – 0.59 56 × 56 740 10

0.62 – 0.68 56 ×56 740 10

0.77 – 0.86 56 ×56 740 10

1.55– 1.70 56 × 56 740 10

OCM 0.4 – 0.885 360 ×360 1420 12

(8 bands @ 20 nm bandwidth)

MOS-A 0.756 – 0.768 1570 ×1400 195 16

(4 bands @ 1.4 nm bandwidth)

-B 0.408 – 1.015 520 × 520 200 16

(13 bands @ 10 mm bandwidth)

-C 1.600 520 ×640 192 16

(1 band @ 100 mm bandwidth)

A.2 Earth Resource Satellite Sensors in the Visible and Infrared Regions 403

Table A.13. RESURS-O1-3 satellite and sensor characteristics

Table A.14. EO-1 sensor characteristics

Instrument Spectral Bands IFOV Swath Dynamic Range

(

µm) (m) (km) (bits)

Hyperion 0.4–2.4 30 × 30 7.7 12

(220 bands @ 10 nm bandwidth)

ALI 0.433–0.453 30 ×30 37 12

0.450–0.515 30 ×30 37 12

0.525–0.606 30 ×30 37 12

0.639–0.690 30 ×30 37 12

0.775–0.805 30 ×30 37 12

0.845–0.890 30 ×30 37 12

1.200–1.300 30 ×30 37 12

1.550–1.750 30 ×30 37 12

2.080–2.350 30 ×30 37 12

0.480–0.690 10 ×10 37 12

(panchromatic)

The principal instruments on Terra are MODIS (Moderate Resolution Imaging

Spectrometer), ASTER (Advanced Spaceborne Thermal Emission and Reﬂection

Spectrometer), CERES (Clouds and the Earth’s Radiant Energy System), MISR

(Multi-angle Imaging SpectroRadiometer) and MOPITT (Measurement of Pollution

in the Troposphere). The instrument complement on Aqua includes MODIS, a set of

optical and microwave atmospheric sounders, CERES, and a scanning microwave

radiometer. The characteristics of MODIS and ASTER are given in Table A.15.

404 A Missions and Sensors

Table A.15. Aqua and Terra sensor characteristics

Instrument Spectral Bands IFOV Swath Dynamic Range

(

µm) (m) (km) (bits)

MODIS

∗

0.620–0.670 250 × 250 2330 12

0.841–0.876 250 × 250 2330 12

0.459–2.155 500 × 500 2330 12

(5 bands)

0.405–14.385 1000 × 1000 2330 12

(29 bands)

ASTER 0.52–0.60 15 × 15 60 8

0.63–0.69 15 × 15 60 8

0.76–0.86 15 × 15 60 8

(backward looking)

1.600–1.700 30 × 30 60 8

2.145–2.185 30 × 30 60 8

2.185–2.225 30 × 30 60 8

2.235–2.285 30 × 30 60 8

2.295–2.365 30 × 30 60 8

2.360–2.430 30 × 30 60 8

8.125–8.475 90 × 90 60 12

8.475–8.825 90 × 90 60 12

8.925–9.275 90 × 90 60 12

10.250–10.950 90 × 90 60 12

10.950–11.650 90 × 90 60 12

∗

The band description for MODIS is quite complex, since groups of bands are tar-

geted on speciﬁc applications. Full details can be obtained from the MODIS home page

at http://modis.gsfc.nasa.gov