Satellite Image Availability
Introduction
Satellite image data are replacing most applications of aerial photographs in nearly all Pacific Island Countries now. This is due to its lower cost and easier use compared with the classical aerial photograph.
To capture aerial photography a special plane has to be brought to a Pacific island, satellite imagery on the other hand are captured by satellites already in space and can record an area whenever it flies over it. To record imagery for Pacific Island Countries a satellite needs an onboard storage device to upload image data. This data is then downloaded ground antennas/receiving station in Kiruna, Sweden as the satellites passes over it. defined the scene centres for The older satellites such as Landsat, record strictly in nadir (directly below) view which meant that the orbit defined the centre of the satellite scene. Fortunately, modern satellites can now either turn themselves or their sensors sideways allowing for a faster coverage of any target area and also at the same time create a mosaic of image patches with different view angles and atmospheric conditions.
TRIVIA: Satellites have a life expectancy of about 5 years. Unlike aeroplanes satellites orbit at a very high altitude and are thus more stable.
The sensors of the old generation satellites such as Landsat and SPOT recorded in 8bit data range on the other hand modern satellites such as IKONOS and QuickBird
? record in 11bit data range, allowing for a more detailed recording but requires a conversion back to 8bit data for use as GIS backdrops.
The price of satellite data always varies thus it is important to get a new quotation for each area. Often companies also have special offers for archived data. The prices listed in this paper include a discount offered by MDA (former RadarSat
? International) to SOPAC. Customers ordering directly from the company and not through SOPAC will not be entitled for this discount.
QuickBird
| Satellite Characteristics
|
| The QuickBird? sensor offers the highest resolution available compared to other commercial satellites and also has128 GB on-board image storage capacity. The image swaths recorded are 16.5 km by 16.5 km. Data is recorded in 11 bit dynamic range however its is delivered to the customer as 16 bit.
|
| QuickBird? 1 was lost during a launch vehicle failure and was replaced withQuickBird 2 launched on 18 October 2001. The satellite has a sun-synchronous (daytime) orbit with an altitude of 450 km and 98 degree inclination. It can also revisit sites within 1 to 3.5 days depending on the latitude. | 
|
Band Coverage
| black&white | 450 - 900 nm | 61cm
|
| blue | 450 - 520 nm | 2.44m
|
| green | 520 - 600 nm | 2.44m
|
| red | 610 - 680 nm | 2.44m
|
| infrared | 790 - 900 nm | 2.44m |
Data Utilisation
Pan-sharpened data 11bit ~ $US 20 per square km for new collection and ~ $US 15 per square km for archive data.
Thematic maps up to scale 1:5,000 possible with pan-sharpened or panchromatic image data. The shape of houses is clearly visible.
Vegetation mapping also possible with pan-sharpened image data as texture allows separation species such as palm separation from natural forest and other vegetation.
Water analysis (bathymetry) is possible utilising blue channel. Sensor is not restricted to nadir view, which can cause wave reflection.
Linear elements are good visible with panchromatic data.
Cost of Image Data
Pan-sharpened data 11bit ~ $US 20 per square km for new collection and ~ $US 15 per square km for archive data. The minimum area for which a customer can order image data is 64 square km.
SOPAC’s archive keeps multi-spectral QuickBird
? image data for Rabi Island and several data sets of pan-sharpened data for other Pacific Island Countries. So far there are no pan-sharpened image data available for Fiji.
IKONOS
| Satellite Characteristics
|
| The launch of IKONOS took place in September 1999 at this time the satellite provided data with highest spatial resolution of all commercial satellites. The satellite has a polar, circular, sun-synchronous orbit of 681 km altitude with an inclination of 98.1 degrees. Both sensors have a swath width of 11 km. The satellite can turn to look sideways and can store 64 GB of image data. Data are recorded in 11bit range. | 
|
Band Coverage
| blue | 450 – 520 nm | 4m
|
| green | 520 - 600 nm | 4m
|
| red | 630 - 690 nm | 4m
|
| near-IR | 760 - 900 nm | 4m
|
| pan | 450 - 900 nm | 1m |
Data Utilisation
Vegetation mapping is possible up to a scale of 1:10,000 using multi-spectral data as pan-sharpened data has limitations for vegetation stratification. The location of houses is visible in multi-spectral data, which is sufficient for thematic maps of 1:10,000 scale. Pan-sharpened IKONOS image data allow to see the shape of houses.
Linear elements are visible in pan-chromatic data and can be mapped.
Bathymetry mapping of shallow water requires the multi-spectral dataset to utilise the blue channel. The data is seldom recorded in nadir view (can be ordered but is more expensive) and reflection of waves can create problems.
There are many data sets available at SOPAC for different parts of Fiji and other Pacific Island Countries.
Cost of Image Data
Multi-spectral image data were ordered for ~ $US 13.50 per square km for new collection. The minimum area for data purchase is 100 square km.
OrbView-3
| Satellite Characteristics
|
| OrbView-3 is currently not fuctioning! The satellite was launched on 26 June 2003 and is the newest high-resolution satellite among those commercially operated. OrbView-3's imaging instrument provides both one-meter panchromatic imagery and four-meter multi-spectral imagery with a swath width of 8 km. The satellite revisits each location on Earth in less than three days with an ability to turn from side-to-side up to 45 degrees. ORBIMAGE currently expects OrbView-3? will have an operational life of 7 years, thus exceeding its 5 year design life. OrbView-3? has 470 km high sun-synchronous orbit. The on-board storage capacity is 4 GB. |  |
Band Coverage
| blue | 450 – 520 nm | 4m
|
| green | 520 - 600 nm | 4m
|
| red | 625 - 695 nm | 4m
|
| near-IR | 760 - 900 nm | 4m
|
| pan | 450 - 900 nm | 1m |
Data Utilisation
The data utilisation is similar to IKONOS as the data specifications in terms of band coverage and resolution are alike.
Cost of Image Data
Multi-spectral and panchromatic image data cost $US 14 per square km. SOPAC did not order OrbView-3
? data so far.
EROS-A1
| Satellite Characteristics
|
| EROS-A1 was launched on 5 December 2000 and is operating in a sun-synchronous, polar orbit at an altitude of 480 kilometres. The satellite is capable of taking high-resolution pan-chromatic pictures of an area of 12.5 km x12.5 km, at a resolution of 1.8 meters. However, modifications of the primary sensor, by applying “over-sampling� techniques, carried out by the manufacturer, have already doubled the system’s performance, providing imaging of a 6.25 km x 6.25 km at a resolution of 1 meter with the existing satellite, with vertical separation of 5 meters, providing accurate mapping and 3D modeling capability of the terrain. The satellite records in 8bit data range storage capacity?. |  |
Data Utilisation
EROS-A1 image data can be utilised as cost saving alternative if only panchromatic data of IKONOS or OrbView-3
? is required and cab also be used to pan-sharpen existing multi-spectral IKONOS or OrbView-3
? data.
Cost of Image Data
EROS-A1 image data costs ~ $US 12 per square km for new collection and ~ $US 5 for archive data. The minimum purchase area is 25 square km for archive data and 100 square km for new collection. Sample image data is available at SOPAC for Lami Suva area
EROS-B
| Satellite Characteristics
|
| EROS-B was launched on 25 April 2006 and is operating in a sun-synchronous, polar orbit at an altitude of 500 kilometres. The satellite
|
| is capable of taking high-resolution pan-chromatic pictures in a strip of 7km width with a spatial resolution of 0.7 meters. |  |
Data Utilisation
EROS-B image data can be utilised as cost saving alternative if only panchromatic data of IKONOS or OrbView-3
? is required and can also be
used to pan-sharpen existing multi-spectral image data.
SPOT-5
| Satellite Characteristics
|
| SPOT-5 was launched on 04 May 2002 with an expected lifetime of 5 years. SPOT orbits the Earth at an altitude of 832 kilometres in a polar, circular, sun-synchronous orbit with an inclination of 98.7 degree. The orbit is phased that the satellite passes over the same point every 26 days. The Equator crossing time is 10:30 a.m. SPOT 5 records in 8bit data range. |  |
Band Coverage and Spatial Resolution
| pan | 490 - 690 nm | 2.5 m or 5 m
|
| green | 490 - 610 nm | 10m
|
| red | 610 - 680 nm | 10m
|
| near-IR | 780 - 890 nm | 10m
|
| SWIR | 1580 - 1750 nm | 20m |
Data Utilisation
SPOT multi-spectral data can be utilised for vegetation mapping up to 1:25,000 scale.
Cost of Image Data
2.5m panchromatic ~ $US 6.750 per scene (60km x 60km) ($US 1.88 per square km)
5m panchromatic ~ $US 3.375 per scene (60km x 60 km)
10m panchromatic ~ $US 3.375 per scene (60km x 60 km)
10 multi-spectral data ~ $US 3.375 per scene (60km x 60 km)
CartoSat
| Satellite Characteristics
|
| Mid 2003, CARTOSAT-1 (before named IRS-P5) was launched into a 618 km high circular, polar, sun synchronous orbit with 98.9 degree inclination. The equator crossing time is 10:30. |  |
Band Coverage and Spatial Resolution
CARTOSAT-1 carries two state-of-the-art Panchromatic (PAN) cameras that take black and white stereoscopic pictures of the earth. The swath covered by these high-resolution PAN cameras is 30 km and their spatial resolution is 2.5 metres. The cameras are mounted on the satellite in such a way that near simultaneous imaging of the same area from two different angles is possible. The cameras operate in the 500 - 750 nm wavelength. CARTOSAT-1 also carries a Solid State Recorder with a capacity of 120 GB to store image data.
Data Utilisation
Linear elements can be mapped up to 1:10,000 scale or slightly better. Vegetation mapping is difficult with black and white image data.
Cost of Image Data
$US 1,800 per scene of 27.5 km by 27.5 km. It is possible to order by area of interest, which will cost $US 2.75 per square km.
RESOURCESAT-1
| Satellite Characteristics
|
| RESOURCESAT-1 was launched on 17.10.03 and is operating in a sun-synchronous orbit at an altitude of 817 kilometres. It crosses the equator at 10:30 local time. The satellite has 120 Giga Bits storage capacity for image data. RESOURCESAT-1 has 3 sensors on board a) the high-resolution Linear Imaging Self Scanner (LISS-4), b) the medium-resolution Linear Imaging Self Scanner (LISS-3) and c) the multi-spectral Advanced Wide Field Sensor (AWiFS). |  |
Band Coverage LISS-4
| green | 520 - 590 nm | 5.8m
|
| red | 620 - 680 nm | 5.8m
|
| NIR | 770 - 860 nm | 5.8m
|
| PAN | | 5.8m |
Band Coverage LISS-3
| green | 520 - 590 nm | 23.5m
|
| red | 620 - 680 nm | 23.5m
|
| NIR | 770 - 860 nm | 23.5m
|
| SWIR | 1550 - 1700 nm | 23.5m |
Band Coverage AWiFS
| green | 520 - 590 nm | 56m
|
| red | 620 - 680 nm | 56m
|
| NIR | 770 - 860 nm | 56m
|
| SWIR | 1550 - 1700 nm | 56m |
Terra
| Satellite Characteristics
|
| The Terra satellite has a sun-synchronous orbit of 705 km altitude. The satellite was launched in December 1999 and sending images of the earth since February 2000. Every 16 days (or 233 orbits) the pattern of orbits repeats itself. Terra carries five scientific instruments: ASTER, CERES, MISR, MODIS, and MOPITT from which ASTER is currently the most interesting one. . The equator crossing time is 10:30. |  |
Band Coverage and Spatial Resolution
ASTER is a cooperative effort between NASA and Japan's Ministry of Economy Trade and Industry (METI), with the collaboration of scientific and industry organisations in both countries. The ASTER instrument provides the next generation in remote sensing imaging capabilities compared with the older Landsat Thematic Mapper, and Japan's JERS-1 OPS scanner. ASTER captures high spatial resolution data (15m in visible and near infrared and 30m in the short wave infrared) in 14 bands, from the visible to the thermal infrared wavelengths; and provides stereo viewing capability for digital elevation model creation. As the "zoom lens" for Terra, ASTER data are used by other Terra and space-borne instruments for validation and calibration.
Data Utilisation
Vegetation mapping at 1:50,000 scale. The blue part of the spectrum is not covered which makes bathymetric application difficult.
Cost of Image Data
About $US 100 per scene, which covers 60km x 60km.
IRS-1C
| Satellite Characteristics
|
| There are two satellites in orbit having similar instruments onboard: IRS-1C and IRS-1D. They both have three sensors 1) panchromatic camera (PAN), 2) Linear Imaging and Self-Scanning? Sensor (LISS - III) and 3) Wide Field Sensor (WiFS). The satellites are equipped with an On Board Tape Recorder (OBTR) for collecting data outside the visibility region of any ground station. |  |
Band Coverage and Spatial Resolution
The PAN camera provides data with a spatial resolution of 5.8 meters and a ground swath of 70 km at nadir view. LISS –III provides following resolution:
| green | 520 - 590 nm | 23m
|
| red | 620 - 680 nm | 23m
|
| near IR | 770 - 860 nm | 23m
|
| SWIR | 1550 - 1700 nm | 70.5m |
The LISS-III revisits the same geographic point in 24 days.WiFS has aswath of 770 km but revisits every three days. The resolution and wave coverage of this sensor:
1) 620 - 680 nm 188m
2) 770 - 860 nm 188m
Data Utilisation
Vegetation maps at 1:50,000 scale can be produced. Bathymetry analysis is difficult due to missing coverage of the blue band.
Cost of Image Data
Panchromatic $US 900 for 23km x 23km
Panchromatic $US 2,500 for 70km x 70km
LISS-III $US 1,900 for 70km x 70 km
Landsat 7
| Satellite Characteristics
|
| Landsat 7 was launched at 15 April 1999 and recorded the first images a few days later. Like the earlier TM sensors, the Landsat7 Enhanced Thematic Mapper Plus (ETM+) provides data in six visible, near infrared (NIR), short wave infrared (SWIR) and mid infrared bands.In addition, ETM+ will provide improved resolution for the thermal infrared (TIR) band (60 m vs. 120 m), a panchromatic band with 15m resolution.Landsat 7 is the latest in a long history of land remote sensing spacecraft, starting with the launch of Landsat 1 in 1972. The Enhanced Thematic Mapper Plus (ETM+) continues the database of Earth imagery begun in 1982 by the Landsat 4 Thematic Mapper. ETM+ provides the same spectral bands for consistent change detection. New is the spatial resolution of 15m provided by an additional panchromatic channel, which was not available on the previous Landsat satellites |
|
| Approximately one quarter of the Earth's landmass will be imaged every 16 days, using a planning scenario that emphasises seasonal changes in vegetation and uses cloud predictions from the National Weather Service to avoid imaging cloudy areas, thus optimising the data acquisition strategy. If the data user wants a particular image, chances are that it is already in the data archive. Also, as environmental changes occur on the Earth's surface, it is highly probable that recent prior data already exists and can be quickly retrieved to compare with newly acquired data.
|
| The Landsat 7 processing system at the EROS Data Center (USA) has been designed to retrieve data from the archive, process, and distribute ETM+ products within 48 hours of receipt of the customer order, which is significantly more responsive than previous Landsat production systems.
|
| Landsat 4 was able to download images from South Pacific Island Countries via relay satellite. Landsat 5 was not able to download images in this way and Fiji s Forestry Department purchased SPOT images, which are more expensive and provide less radiometric information. Now, the onboard tape drive can store 100 images and the satellite records again areas from the Pacific Island Countries |
Band Coverage and Spatial Resolution
| blue | 450 - 515 nm | 30m
|
| green | 525 – 605 nm | 30m
|
| red | 630 - 690nm | 30m
|
| near-infrared | 750 – 900 nm | 30m
|
| short-wave infrared | 1550 - 1750 nm | 30m
|
| mid infrared | 3090 - 2.35 nm | 30m
|
| thermal infrared | 10400 - 12500 nm | 60m
|
| panchromatic | 520 - 900 nm | 15m |
Data Utilisation
Wide range of application, bathymetry, vegetation mapping. The limit is 1:50,000 scale.
Cost of Image Data
Free!
ENVISAT
| ENVISAT (European Environmental Satellite)
|
| Since beginning of March 2002, Envisat is orbiting in an Earth polar orbit at 800 km altitude and is an automatic space observatory with ten highly sophisticated instruments observing the Earth. End of March Envisat delivered the first data. In September 2002 operational data distribution is expeceted.Envisat will serve a vast community of users, delivering data products for Earth science research, development of pilot application projects, public services and commercial uses. Designed for 5 years operation in orbit, Envisat is the leading satellite supporting the European initiative for Global Monitoring for Environment and Security (GMES) | 
|
| ENVISAT carries several instruments that will help unravel the mysteries of our planet.
|
| * ASAR provides radar images, independent of the underlying weather conditions, to monitor the tiniest changes of the earth surface, helping in the characterisation of manmade or natural disasters;
|
| * GOMOS monitors precisely the ozone distribution all over the globe;
|
| MIPAS and SCIAMACHY create global, three-dimensional maps of most trace gases in the atmosphere, observing in particular the greenhouse gases, like methane and carbon monoxide;
|
| * AATSR creates the most accurate global picture of sea surface temperature;
|
| * MERIS observes the "colour" of the ocean over a wide range of wavelengths to provide precise marine biology information and vital insight into global warming by mapping the distribution of phytoplankton, which account for half of the absorption of greenhouse carbon dioxide by our planet's biosphere;
|
| * The Radar Altimeter monitors the smallest changes in the sea level and in the topography of the polar ice caps.
|
| For Pacific Island Countries the AATSR and the MERIS sensors will be of high interest to monitor the fishing conditions of the EEZs |
MERIS (MEdium Resolution Imaging Specrometer Instrument)
MERIS is a 68.5 o field-of-view pushbroom imaging spectrometer that measures the solar radiation reflected by the Earth, at a ground spatial resolution of 300m, in 15 spectral bands, programmable in width and position, in the visible and near infra-red. MERIS allows global coverage of the Earth in 3 days. MERIS measures the sea colour of the oceans and in coastal areas. Knowledge of the sea colour can be converted into a measurement of chlorophyll pigment concentration, suspended sediment concentration and of aerosol loads over the marine domain.
Band
| Nr. | Band centre (NM) | Bandwidth (NM) | Potential Applications
|
| 1 | 412.5 | 10 | Yellow substance and detrital pigments
|
| 2 | 442.5 | 10 | Chlorophyll absorption maximum
|
| 3 | 490 | 10 | Chlorophyll and other pigments
|
| 4 | 510 | 10 | Suspended sediment, red tides
|
| 5 | 560 | 10 | Chlorophyll absorption minimum
|
| 6 | 620 | 10 | Suspended sediment
|
| 7 | 665 | 10 | Chlorophyll absorption and fluo. reference
|
| 8 | 681.25 | 7.5 | Chlorophyll fluorescence peak
|
| 9 | 708.75 | 10 | Fluo. Reference, atmospheric corrections
|
| 10 | 753.75 | 7.5 | Vegetation, cloud
|
| 11 | 760.625 | 3.75 | Oxygen absorption R-branch
|
| 12 | 778.75 | 15 | Atmosphere corrections
|
| 13 | 865 | 20 | Vegetation, water vapour reference
|
| 14 | 885 | 10 | Atmosphere corrections
|
| 15 | 900 | 10 | Water vapour, land |
The high-lighted bands 1 to 8 will be of interest for monitoring the fishing conditions of Pacific Island Countries.
For further information contact:
wolf@sopac.org.fj or subscribe to
GIS-PACNet@list.sopac.org.fj
update by Wolf 02.06.02
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