Subject: Satellite Imagery FAQ - 2/5
Supersedes: <sci/Satellite-Imagery-FAQ/part2_827207059@rtfm.mit.edu>
Date: 19 Apr 1996 05:18:54 GMT
References: <sci/Satellite-Imagery-FAQ/part1_829890621@rtfm.mit.edu>
Summary: Satellite Imagery for Earth Observation
X-Last-Updated: 1996/04/16


This document is part the Satellite Imagery FAQ

Satellite Imagery

What are the main Earth Observation Satellites and Instruments?

------------------------------

Subject: Weather Satellites

Weather Satellites

I know nothing about these: need to find some info.

The Meteosat GOES amd GMS weather satellites operate in geostationary orbits.
That is to say, they orbit the Earth at the same speed as the Earth's rotation,
thus constantly viewing the same area. This means that their temporal
resolution is effectively unlimited, so they are able to generate the familiar
weather 'movies'.

They are, however, of limited use for (other) remote sensing purposes.
Geostationary orbits (more typical of communications satellites) are
constrained to high altitude, and to the equator. Thus good viewing angles over
high latitudes are not possible. The very large area images are at low spatial
resolution; the best achieved by Meteosat and GOES is 2.4Km (?).

Click here for a few pointers to weather pictures online, or see the
Meteorology Resources FAQ for a far longer list.

------------------------------

Subject: Earth Observation Satellites (for geosciences, etc)

Earth Observation Satellites

See also the list below, containing pointers to detailed information and online
imagery.

Earth Observation imagery takes a number of forms, of which the most
traditional are optical and near-infrared radiation, from about 0.4 (blue) to
2.0 (IR) micrometers. Examples include Landsat, Spot and NOAA. These generally
use tracking instrunents, the basic principles of which are briefly described
in Part 2 of this FAQ (someone point me to a proper intro on the net - SURELY
there must be one)!.

Colour

After basic processing, imagery from these satellites may appear as
photographs. With certain visual imagery - eg SPOT - it is even possible to
display images in more-or-less their natural colour. In practice, images for
display are generally manipulated to appear visually pleasing and to show
interesting detail, and appear in false colour. Visible and non-visible (IR)
bands may be freely mixed in false colour images. There are no firm rules about
this, but by convention clouds are shown as white, and vegetation red or green,
depending on the context.

Resolution

Resolution is determined primarily by instrument design, and generally involves
various compromises:

  1. High spatial resolution implies imaging a small area. For an image of 1000
     pixels square, at 20m resolution the area viewed is 20x20Km, but at 1Km
     resolution this increases to 1000x1000Km (actually rather more, due to the
     variation in viewing angle over a large area). The latter is therefore
     intrinsically suited to large-scale studies.
  2. High spatial resolution also implies a high sampling frequency, which may
     limit the sensitivity of the sensor.

Types of Imagery

Apart from visual and near-infrared, other bands of the spectrum commonly used
include thermal infrared (heat) and microwave (radar). Each of these has its
own applications.

3-dimensional Imagery

We see the world in three dimensions by virtue of having two eyes, viewing the
world at slightly different angles. It is possible to emulate this and produce
3-dimensional (stereo) satellite imagery, by superimposing images of the same
ground area, viewed from different angles (and at different times). A limited
number of satellites have this capability.

------------------------------

Subject: Synthetic Aperture Radar (SAR)

Synthetic Aperture Radar

What is SAR?

Synthetic Aperture Radar. An active microwave instrument, producing
high-resolution imagery of the Earth's surface in all weather.

There is a good introduction to imaging radar by Tony Freeman of JPL at
http://southport.jpl.nasa.gov/desc/imagingradarv3.html

Should we have an embedded intro for the benefit of non-WWW readers? I can ask
to include the above, or try and solicit an equally expert intro from someone
here

What are the main SAR platforms?

Several past, present and future Earth Observation Satellites. Also the Shuttle
Imaging Radar missions. See the table for a full list.

   * ERS-1/ERS-2
   * JERS-1
   * Shuttle Imaging Radar SIR-C/X-SAR
   * Almaz

the future...

   * RadarSat
   * ENVISAT (I'm not even making a link until I've something REAL to put
     there)!
   * OK, what have I forgotten about (or never heard of)?

What distinguishes SAR from hi-res optical imagery?

Two main properties distinguish SAR from optical imagery:

   * The SAR is an active instrument. That is to say, it generates its own
     illumination of the scene to be viewed, in the manner of a camera with
     flash. The satellite's illumination is coherent: i.e. all the light in any
     flash is exactly in phase, in the manner of a laser, so it does not simply
     disperse over the distance between the satellite and the Earth's surface.
     A SAR instrument can measure both intensity and phase of the reflected
     light, resulting not only in a high sensitivity to texture, but also in
     some three-dimensional capabilities. Experiments with the technique of
     Interferometry (measuring phase differences in exactly aligned images of
     the same ground area) have shown that SAR can accurately model relief, and
     appears able also to detect small changes over time. A paper describing
     the technique and experiments is available at
     http://gds.esrin.esa.it/A0x0000001c.

     Some consequences of being an active instrument (and using coherent light)
     are:
        o Works equally day or night
        o Polarised - can be used to gain additional information (esp. when
          different polarisations are available on the same platform - as on
          the most recent Shuttle missions).
        o Needs a lot more power than passive sensors, and can therefore only
          operate intermittently.
        o Suffers from speckle, an artifact of interference patterns in
          coherent light, sensitive to texture.

   * SAR is Radar - i.e. it uses microwave frequency radiation. (note that in
     consequence, references to "light" above should more strictly read
     "microwave radiation"). Microwave radiation penetrates cloud and haze, so
     SAR views the Earth's surface (land and sea) in all weather. For general
     purpose Remote Sensing, this is probably the major advantage of SAR.

     An example of its use is the ESA/Eurimage "Earthwatch" programme,
     producing imagery of natural and other disasters when weather conditions
     prevent other forms of surveillence. Earthwatch imagery is available at
     http://gds.esrin.esa.it/CSacquisitions

What are SAR images good for ?

this wants a better entry - else I'll just point to a bibliography on the Net

   * Sensitive to texture: good for vegetation studies.
   * Ocean waves, winds, currents.
   * Seismic Activity
   * Moisture content

What is the meaning of colour in a SAR image?

Of course, all SAR image colour is false colour: the notion of true colour is
meaningless in the context of invisible microvawe radiation.

Most SAR images are monochrome. However, multiple images of the same scene
taken at different times may be superimposed, to generate false-colour
multitemporal images. Colour in these images signifies changes in the scene,
which may arise due to a whole host of factors, such as moisture content or
crop growth on land, or wind and wave conditions at sea. SAR is particularly
well-suited to this technique, due to the absence of cloud cover.

The shuttle SAR's images are the nearest to 'natural' colour, in the sense that
they are viewing three different wavelengths, which can be mapped to RGB for
pseudo-naturalistic display purposes (essentially the same as false colour in
optical/IR imagery).

Need a proper multitemporal image entry
-------------------------------------------------------------------------------

Radar Altimetry

Technique used extensively to map the oceans. There are introductions at
http://www.satobsys.co.uk/home_page.html and
http://dutlru8.lr.tudelft.nl/pages/atlas.html. The latter includes the
Altimetry Atlas, computed from GEOSAT, ERS-1 and TOPEX-Poseidon altimetry data.

An interactive browser offering sea surface height maps is available at
http://www.ccar.colorado.edu/~hendricj/topexssh.html
-------------------------------------------------------------------------------

------------------------------

Subject: List of some Earth Observation Satellites

What are the main Earth Observation Satellites and Sensors

Here is a list of some EO missions. These entries should become html links to
further information (esp. details of imagery and where to get it if applicable)
on an ad-hoc basis, as and when I have the information to put there
(contributions sought) and the time to edit them in.

For detail on any of the following (and others), try a keyword search on
Esrin's GDS at http://gds.esrin.esa.it/.

See also http://gds.esrin.esa.it/CIDN_PROVA.source

   *  ADEOS Advanced Earth Observing Satellite (launch 1996, Japan)
        o  OCTS Ocean Color and Temperature Scanner
        o  AVNIR Advanced Visible and Near-Infrared Radiometer
        o  NSCAT NASA Scatterometer
        o  TOMS Total Ozone Mapping Spectrometer
        o  POLDER Polarization and Directionality of the Earth's Reflectance
        o  IMG Interferometric Monitor for Greenhouse Gasses
        o  ILAS Improved Limb Atmospheric Spectrometer
        o  RIS Retroflector in Space
   *  Almaz
        o SAR
   *  DMSP Defense Meterological Satellite Program
        o  SSM/I (Special Sensor Microwave/Imager)
        o  Visible
        o  SSM/T1, SSM/T2 Microwave temperature & moisture sounders
   *  ERS-1 Earth Resources Satellite
        o  AMI (Active Microwave Instrument), Wind mode, Wave mode, SAR
          (Synthetic Aperture Radar)
        o  Radar Altimeter
        o  ATSR-M (Along-Track Scanning Radiometer and Microwave Sounder)
        o  PRARE (Precise Range & Range Rate Equipment)
   *  ERS-2 as ERS1 with addition of
        o GOME Global Ozone Monitoring Experiment
   *  GEOS Geodynamics Experimental Ocean Satellite
   *  GEOSAT GEOdetic SATellite
   *  GMS Geostationary Meteorological Satellites (140 E)
        o  VISSR (Visible and Infra-red Spin Scan Radiometer)
   *  GOES Geostationary Operational Environmental Satellite (75 W and 135 W)
        o  VISSR (Visible and Infra-red Spin Scan Radiometer) altimeter
   *  HCMM Heat Capacity Mapping Mission
        o  HCMR (Heat Capacity Mapping Radiometer), visible + thermal
   *  INSAT Geostationary satellite of India (74 E)
   * IRS Indian Remote Sensing Satellite System
        o  PAN - Panchromatic Camera
        o  LISS I - III (Linear Imaging Self Scanning Sensors)
        o  WIFS
   * JERS-1 Japanese Earth Resources Satellite
        o  OPS Optical Sensors
        o  SAR (Synthetic Aperture Radar)
   * KOSMOS Russian EO satellite
   * Landsat
        o  TM (Thematic Mapper)
        o  MSS (Multi-Spectral Scanner System)
        o  RBV (Return Beam Vidicon) camera
   *  METEOR Russian meteo satellites (2-21, 3-3, 3-5)
   * Meteosat (0 E, Greenwich meridian)
        o  Visible/near infra-red
        o  middle IR
        o  Watervapour, thermal infra-red
   *  MOS Marine Observation Satellite
        o  MESSR Multispectral Electronic Self Scanning Radiometer
        o  VTIR Visible and Thermal Infrared Radiometer
        o  MSR Microwave Scanning Radiometer
   * Nimbus 7
        o  CZCS Coastal Zone Color Scanner
        o  ERB Earth Radiation Budget
        o  LIMS Limb Infra-red Monitor for the Stratosphere
        o  SAM-II Stratospheric Aerosol measurement (II)
        o  SAMS Stratospheric and Mesospheric Sounder
        o  SBUV Solar and Backscatter ultraviolet Spectrometer
        o  TOMS (Total Ozone Mapping Spectrometer)
        o  SMMR (Scanning Multichannel Microwave Radiometer)
        o  THIR Temperature Humidity Infra-red Radiometer
   * NOAA Polar Orbiting Environmental Satellites (series)
        o  AVHRR Advanced Very High Resolution Radiometer
        o  TOVS (TIROS Operational Vertical Sounder)
        o  SBUV/2 Solar Backscatter Ultraviolet Spectrometer
   * Radarsat (Canada)
        o  SAR
   * RESURS

     See the Russian Imagery entry in this document.
   * SeaStar
        o SeaWiFS Sea-viewing Wide Field-of-view Sensor
   *  SeaSat Ocean Dynamics Satellite
        o  SAR L-band
        o  ALT Radar altimeter
        o  SASS Radar Scatterometer
        o  SMMR Scanning Multi-Spectral Microwave Radiometer
        o  VIRR Visible en Infra-red Radiometer
   * Shuttle
        o  SIR-A Shuttle Imaging Radar
        o  SIR-B
        o  SIR-C (cross polarized returns VH and HV) (Apr+Oct 1994)
        o  LFC Large Format Camera
        o  MOMS Modular Opto-electronic Multi-spectral Scanner (2 bands)
   *  SkyLab
        o  S 192 MSS Multispectral Scanner
        o  Metric camera experiment
   * SPOT
        o  HRV High Resolution Visible (2x) has 2 modes:
             +  XS (MultiSpectral mode)
             +  PAN (PANchromatic mode)
   *  SPOT 4 (launch 1995)
        o  HRVIR High Resolution Visible and Infrared
   *  TIROS, TOS and ITOS forerunners of the current NOAA series (9-12+14, 13
     failed just after launch). See NOAA above.
        o  AVHRR Advanced Very High Resolution Radiometer
        o  TOVS (TIROS Operational Vertical Sounder) consisting of:
             +  HIRS/2 infra-red sounder
             +  SSU stratospheric sounding unit
             +  MSU microwave sounding unit
   * TOPEX/POSEIDON
        o ALT Radar Altimeter
        o TMR TOPEX Microwave Radiometer
        o LRA Laser Retroreflector Array
        o SSALT Single-Frequency Solid-State Radar Altimeter
        o DORIS Dual-Doppler Tracking System Receiver
        o GPSDR GPS Demonstration Receiver
   * TRMM Tropical Rainfall Measuring Mission (launch 1997, Japan)
        o  PR Precipitation Radar
        o  TMI TRMM Microwave Imager
        o  VIRS Visible Infrared Scanner
        o  CERES Clouds and the Earth's Radiant Energy System
        o  LIS Lightning Imaging Sensor

-------------------------------------------------------------------------------

------------------------------

Subject: Military / Intelligence Imagery

Military / Intelligence Imagery

Didn't President Clinton recently declassify some military imagery?

By an order dated 23rd Feb 1995,

   * Imagery from the CORONA, ARGON, and LANYARD missions to be declassified
     within 18 months.
   * Review process to be instituted for other imagery.

Details and imagery are available at
http://edcwww.cr.usgs.gov/dclass/dclass.html.
-------------------------------------------------------------------------------

------------------------------

Subject: Russian Imagery

Russian Imagery

Contributed by W. Steven Sklaris (then of DBA systems; now ssklaris@tds.com).
Information regarding suppliers and availability applies to the USA; elsewhere
YMMV.

What about Russian Satellite Imagery?

The Russian Federation through the Russian Space Agency permits the sale of
commercial multi-source satellite imagery. The current restriction placed on
this imagery is limited to 2 meter resolution but 1 meter resolutions are
currently being considered. The majority of commercial sources are from film
return systems. The technical philosophy is that the highest quality ground
resolve is acquired by film systems - no argument. The two primary commercial
satellites are KOSMOS, RESURS and Okean. The KOSMOS is utilized by the ministry
of Defense. RESURS and Okean satisfies environmental and weather monitoring.

What are the characteristics of the KOSMOS satellite systems?

The KOSMOS has on board 2 camera systems; the KVR-1000 and TK-350. The main
attraction of the system is for mapping applications. The TK-350 is a frame
camera that provides 80% overlap between images (every third image provides
60%), along with internal and external orientation data. This system provides
for accurate determination of latitude, longitude and elevation. The TK-350
covers an approximately 265 x 170 kilometer area per image and an 8 to 10 meter
resolution. The ground feature characteristics are provided by the KVR-1000
camera. This camera system operates simultaneously with the TK- 350 and
provides 10% overlap between images. This is a panoramic camera with 2 meter
ground resolution and 36 - 44 x 165 kilometer area.

What are the characteristics of the RESURS satellite system?

The RESURS-O consists of the 01 and 02 series and are direct digital return
systems.

The RESURS-01 has on-board 2 sensor systems; the MSU-E and MSU-SK. The MSU-E is
a three channel system covering the 500 to 900 nanometer band range. The sensor
has a resolution of 45 meters and covers a 45 kilometer swath. The MSU-SK has 5
distinct channels covering the 540 to 11,800 nanometer band range. This sensor
has a resolution of 160 meters for the first 4 channels and 600 meters for the
5th channel and covers a 600 kilometer swath.

The RESURS-02 is an upgraded version of the 01 and has 4 on-board sensor
systems; the MSU-E, MSU-SK, SLR "Travers-1T" and MW-radiometer "Delta-2." The
MSU-E on this more recent satellite system covers the same 3 channels as that
of the 01 but the resolution has improved to 25 to 30 meters while retaining
the 45 kilometer swath. The MSU-SK is again included on the RESURS- 02 with no
improvement from the 01 version. The Synthetic Aperture Radar "Travers-1T" and
Micro Wave radiometer "Delta-2" operate at a radiation wave length of 23cm. The
Travers-1T has a ground resolve of 200 x 200 meters and a swath width of 100
kilometers. The Delta-2 has a ground resolve of 17,000 x 90,000 meters and a
swath width of 1,000 kilometers.

The RESURS-F consists of the F1, F2 and F3 series.

The RESURS-F1 is the oldest and has on-board 2 camera types; the KATE-200 and
KFA-1000. The KATE-200 is a frame camera with a ground resolution of 15 to 30
meters and covers a ground area of 240 x 240 kilometers. The camera system has
three separate film bands covering 500 to 850 nanometers. The KFA- 1000 is an
excellent higher resolution color spectrazonal film camera and coverage of 80 x
80 kilometers. The resolution advertised is 6 to 8 meters but is more around 8
to 10 meters. The color spectrazonal film covers the 570 to 680 nanometer and
680 to 810 nanometer band ranges.

The RESURS-F2 is a more sophisiticated topographic camera system. The MK-4 is a
true multi-spectral camera system with data recorded on three separate black
and white film bases. There are 6 available bands (460 to 900 nanometers) from
which 3 can be selected for imaging. The resolution of the MK-4 is about 6 to 8
meters and advertised to be excellent for cartographic, environmental and
geological surveys. The coverage of the MK-4 is 150 x 150 kilometers. The
RESURS-F2 has on-board 2 stellar cameras to augment orientation accuracy
information but in almost all cases the cameras are not operated. Because of
this the cartographic capabilties are limited without ground control. The
excellent features of the camera are in the resolution and separate band
characteristics.

The RESURS-F3 is the most recent system and the most impressive. The
panchromatic frame camera covers 30 x 30 kilometers with at least 2 meter
resolution. The 1:70,000 to 1:90,000 scale of the imagery provides excellent
ground definition.

What are the characteristics of the Okean?

The Okean-O is also a digital data return system and known to operate for ocean
monitoring. This satellite has on-board 6 sensor systems; the MSU-V, MSU-SK,
MSU-M, SLR, Scanning MW-radiometer "Delta-2", Track MW-radiometer R- 600 and
the Track VW-radiometer. The MSU-V is a eight channel system, the spectral
range is unknown. This sensor has a resolution of 50 meters in the first 4
channels, 100 meters in the 6th channel and 275 meters in the 7th and 8th
channels and covers a 180 to 200 kilometer swath The MSU-SK has 5 distinct
channels covering the 540 to 11,800 nanometer band range. This sensor has a
resolution of 160 meters for the first 4 channels and 600 meters for the 5th
channel and covers a 600 kilometer swath. The MSU-M is a four channel system,
the spectral range is unknown. The sensor has a resolution of 1,600 to 2,000
meters and covers a 1,900 kilometer swath. The Side Looking Radar operates at a
radiation wavelength of 3.1cm at a ground resolution of 800 to 1,500 meters and
a swath width of 450 kilometers. The Scanning Microwave radiometer "Delta-2"
can operate at a wavelength of 0.,8, 1.35, 2.2 or 4.5cm. The resolution is from
20,000 to 100,000 meters and covers a 800 kilometer swathwidth. The Track
Microwave radiometer R-600 operates at a wavelength of 6cm and has a resolution
of 130 meters (swath width unknown). The Track VW-radiometer operates at a
wavelength of 2.25 cm and also has a resolution of 130 meters (swath width
unknown).

What about all of the problems concerning Russian sources?

Numerous problems have been encountered with purchasing satellite source from
Russia. Most of the problems stemmed from the unauthorized source distributors.
Most distributors had access to the archives and conducted a 1 or 2 time sale
before they got caught. The Russian Space Agency is now controling this
distribution activity and has eliminated this problem. Several other problems
still exist and will not be resolved in the near future. Access to coverage in
a timely manner is one. The archives of the KOSMOS system are not catalogued in
a digital form and acquiring coverage information is extensive and timely.
Information on coverage is typically provided in a week (depending on the
extent of coverage requested). The cloud cover information provided with the
coverage plots are very accurate but does not satisfy all users. Several
distributors of the TK-350 are preparing digitization and browsing of the
archived image files. Core Software is considered to be the furthest along in
this venture. A digital database of the RESURS-F exists and provides extensive
information relating to coverage and collection detail. DBA Systems has a copy
of this database in their Melbourne, Florida office and can provide quick
turn-around information. The time to acquire the imagery has been another
problem area. This is much improved and is dependent on the amount of coverage
requested. A single image request, once selected from the coverage plot, will
take approximately 5 to 7 work days. Part of this delay is due to the shipping
services (DHL is 3 days from Moscow). Film quality has also been questioned and
although the processing has significantly improved, many of the archived images
are scratched and were poorly processed during original production.

Can the film sources be provided in digital form?

Several distributors now provide the film sources in digital form. EOSAT and
DBA Systems both can perform digitization of the KVR-1000 down to the 45m range
but only DBA can provide a continuous scan of the entire TK-350 image down to
the 45m spot size if desired (125m is recommended). The precise scanning of
their custom build scanner retains the metric accuracy of the frame image. Any
of the RESURS-F films can also be scanned by the DBA scanner and JEBCO has also
provided digital product from the RESURS-F archives but we are unsure whether
the JEBCO source is still available. The color spectrazonal film of the
KFA-1000 cannot currently be captured by the DBA scanner and other providers of
color scanning of the KFA-1000 are unknown.

How can I purchase Russian Imagery?

There are several suppliers of Russian imagery and value-added products created
from the various Russian satellite systems. EOSAT, through authorized Russian
distributor Kieberso, provides digital KVR-1000; Core Software through
authorized Russian distributor SOVINFORMSPUTNIK, provides hardcopy and digital
KVR-1000 and TK-350; DBA Systems through multiple authorized Russian
distributors of KOSMOS, RESURS and ALMAZ, provides the majority of Russian
satellite sources in both hardcopy and digital form.

Are the Russian planning any future commercial satellite systems?

Yes, the RESURS-F1M and RESURS-F2M will be upgrades to the existing film return
systems and a newer system referred to as Nika-Kuban will be added to the
RESURS satellite family. The Nika-Kuban will operate 3 camera systems and 1
forward looking digital return system to assist in eliminating collection of
cloud covered imagery. The Nika-Kuban will offer panchromatic and multispectral
collection in the 3 to 6 meter resolution range. Also planned as a major player
in the commercial remote sensing industry will be the ALMAZ-1B and ALMAZ-1C.
Both systems are currently awaiting financing to complete development but will
house the most sophisticated array of remote sensing systems available in the
commercial market. The ALMAZ-1B will offer a unique, complex, multi-sensor
payload providing for the first time, a capability for simultaneous,
multi-sensor, high resolution imagery, including single-pass stereo coverage in
the optical and multispectral bandwidths; and high resolution, two-pass, all
weather stereo in microwave bandwidths.

Russian Imagery section by
W. Steven Sklaris
DBA Systems, Inc.
1200 South Woody Burke Rd.
Melbourne, Florida 32901
ph:  1-800-622-8554
fax: (407) 727-7019

------------------------------

Subject: Where can I get Imagery?

Where can I get Imagery?

This very frequently asked question has several parts, which are addressed in
various parts of this FAQ:

   * Where can I get full products? (LIST - TBD)
   * Where can I see/get samples of [some satellite's imagery] ?
   * Where can I browse imagery for [some specific geographic location]?
     Most of the references in this FAQ are global in scope - enter lat/long or
     click a map.
   * Where can I get current weather pics (online) ?
   * Where can I browse images on the Web?
   * Where can I get whole-world images?
   * Where can I get full-resolution imagery cheap or free?
   * Where can I get imagery for [my type of application]?
     That's outside the scope of this document - for the time being at least -
     but check in the Further Reading

------------------------------

Subject: How do I access the imagery catalogues?

How do I access the imagery catalogues?

There are a number of catalogue services available for interactive login, via
telnet; a few of these also offer alternative access methods, including WWW.
These will give full catalogue information, and browse products online
(typically by ftp). Some addresses for these are listed under further reading.

CEOS IDN

The CEOS International Directory Network comprises three coordinating nodes,
together with a number of cooperating nodes. Each coordinating node includes
access to every known imagery catalogue, so in principle you never need more
than one address. These are listed in further information.

Cintex

The Catalogue Interoperability Experiment aims to ensure interoperability
between the various catalogues.

GUIs for catalogue access

Various dedicated GUI systems exist to assist CINTEX catalogue users. These
include:

   * DLR ISIS
   * ESA UIT
   * NASA EOSDIS V0 IMS

Details are available at http://gds.esrin.esa.it/Ccintex.cs.clients.

WWW Browse Services

In addition to the login services, there are some services available on the
WWW, offering a world-map and forms-based interface. These include:

http://shark1.esrin.esa.it/
     Ionia AVHRR browser
http://tracy.esrin.esa.it:8001/
     Eye-Browser Multi-Mission Browse Service: NOAA AVHRR, ERS-1 SAR, JERS OPS,
     Landsat TM.
http://www.coresw.com
     "Imagenet" service - Landsat, SPOT and a promise of Sovinformsputnik.
     Appears only to have data for America when last checked. Commercial; the
     free service is limited.
http://www.eurimage.it/einet/einet_home.html
     EiNet (European Imagenet) from Eurimage offers Landsat TM, KVR-1000 and
     RESURS.
http://southport.jpl.nasa.gov/general.html/
     SIR-C/X-SAR (Space Shuttle) imagery.
http://ic-www.arc.nasa.gov/ic/projects/bayes-group/Atlas/Earth/
     Browser for Earth Observations from Shuttle (but either I or they have a
     problem that needs fixing: someone tell me if it will actually serve you
     images)?

------------------------------

Subject: Where can I get full-resolution imagery cheap or free?

Where can I get full-resolution imagery cheap or free?

Answer 1: In general, you can't!
Answer 2: Old Landsat. The following was posted by Wim Bakker on IMAGRS-L:

Paul DeVries (bosse@bahnhof.se) writes:

> Can anyone point me in the direction of satellite imagery of (dry) Andean
> altiplano, very cheap or in the public domain, of any vintage? Thanks.

In principle the old Landsat TM (acquired from July 16, 1982 through
September 27, 1985) and old Landsat MSS (older than 2 year) are
available at reduced prices:

        MSS                             $ 200
        TM raw                          $ 300
        TM systematic corrected         $ 425
        TM precision corrected          $ 600

Inquires can be made to

        Customer Services
        EROS Data Center (EDC)
        Sioux Falls SD 57198
        (605)-594-6151

In the mean time you can check on the Inventory service of EDC

URL             telnet://glis.cr.usgs.gov

whether any images of your area of interest are available.

What datasets are available on CD-ROM?

Wim Bakker's report "Remote Sensing Data and GIS data on CD-ROM" is available
at http://www.itc.nl/info/rs-data/index.html

Note - this is referenced for want of a better list, but is not kept
up-to-date.
-------------------------------------------------------------------------------

------------------------------

Subject: Whole-World Images

Whole-World Images

This answer is slanted towards Global AVHRR Land datasets. Anyone care to talk
about other images?

Why create whole-world images?
     Because they're fun, of course! :-)
     Continental to global scale images are useful if they show information
     that is studied at a large scale, such as the state of the global
     biosphere. One major measure is NDVI, which characterises 'greenness' (see
     RS/Vegetation FAQ for details). Global NDVI images taken regularly over
     time - at intervals between one and two weeks - enable scientists to study
     change in the biosphere in detail.

How do they create whole-world images
     The AVHRR Pathfinder and Global 1KM projects have created global land
     datasets showing NDVI (together with lower-level data) from AVHRR imagery,
     at resolutions up to 1.1KM. The global images are created by mosaicing a
     large number of individual scenes, taken over ten-day periods. Individual
     scenes are first stitched to generate half-orbits (in principle south to
     north pole, but generally broken because only daytime data is used)! The
     half orbits are then stitched together, with reference to a digital chart
     of the world.

     The key to compositing for NDVI is that each point on the Earth's surface
     is replicated in several images over the sampling period. Only the best
     NDVI value is selected, so bad data (such as cloud cover) is discarded.

Why AVHRR? Why not, say, Landsat?

     Yes, Landsat data is just as well-suited to computing NDVI as is the
     AVHRR.

     The NOAA satellites, in a polar orbit at an altitude of 833 KM, orbit the
     Earth fourteen times per day. The AVHRR instrument images a 2400-KM wide
     swath as it passes. Thus every point on the Earth's surface is viewed at
     least about once per day (the exact frequency of course varies with
     latitude).

     The Landsat series (4-5), in near-polar orbits at 705 KM, also orbit the
     Earth fourteen times per day. However, the swath imaged is just 185KM, so
     a point on the equator may be viewed only once in sixteen days. The data
     with which to generate weekly, ten-day or fortnightly global composites is
     simply not available. A sixteen-day composite would of course be subject
     to considerable cloud-cover (see below).

     Having said that, it is certainly possible to make large-area Landsat
     mosaics. NASA's Landsat Pathfinder Project (see
     http://pathfinder-www.sr.unh.edu/pathfinder/) has created such datasets
     for the study of tropical deforestation.
How do they get rid of the cloud?
     As noted above, only the best NDVI values from each input dataset is used.
     Clouds will necessarily generate very low NDVI values - clouds are not
     green!. Hence clouds are automatically filtered out in the compositing
     process, provided there is at least one cloudless view of a point within
     the sample. Thus cloudlessness is not in fact guaranteed, but is
     statistically far more likely than for a single pass. Alternatively, it
     can be assured by collecting data over an unlimited time period; c.f. the
     GeoSphere project).

     Clearly this will work if and only if the characteristics being studied
     are dissimilar to any cloud in at least one of the available bands!

Further reading:

http://sun1.cr.usgs.gov/landdaac/1KM/1kmhomepage.html
     Global Land 1-KM Project Front Page from USGS/EDC. Includes extensive
     description of the project, and access to the data.
http://shark1.esrin.esa.it/
     Ionia browser - AVHRR scenes and a browse version of a global composite
     from ESA/ESRIN
http://xtreme.gsfc.nasa.gov/
     AVHRR Land Pathfinder from NASA/GSFC - various global composites.
http://infolane.com/infolane/geosphere/geospher.html
     The GeoSphere project (commercial)

All the above references deal with global land datasets. NASA's pathfinder
program created also Ocean and Atmospheric datasets:

http://sst-www.jpl.nasa.gov/
     SST Pathfinder from NASA/JPL
http://pegasus.nesdis.noaa.gov//pathfinder.html
     Atmosphere pathfinder from NOAA

General Questions

------------------------------

Subject: Programmes and Policies

What are the National and International Remote Sensing programmes around the
World?

(Should I have a brief summary and/or plain list here?

This is dealt with in detail in a US Congress (Office of Technology Assessment)
report "Remotely Sensed Data: Technology, Management and Markets", Chapter 5.
Whilst this *is* explicitly a US government document, it is generally an
objective summary!

The report is available online at http://otabbs.ota.gov/T90 (thanks to
Mark_Goodman@achre.gov for drawing my attention to the OTA reports).

Where can I read about government policies in Remote Sensing

USA: See also the previous question.
The US Congress (Office of Technology Assessment) has published some detailed
reports, two of which are available online. In addition to the report
referenced in the previous question above, "Civilian Satellite Remote Sensing:
A Strategic Approach" is available at http://otabbs.ota.gov/T85.

Others: AFAIK no such government documents are available elsewhere (but see
CEOS below for worldwide policy coordination). Check the various space agency
pages, listed under URLS.

------------------------------

Subject: Where can I find information on RS and the Environment

Resources concerning the Environment

This is far too big a subject to cover in this FAQ, so here are some links,
limited to major (and established) collections:

Environmental Resources Information Network, ERIN (Australia)
     The ERIN homepage is at http://kaos.erin.gov.au/erin.html (formerly listed
     under misc. URLS)
Global Environmental Research Federal Metadata Network GENIE
     at http://www-genie.lut.ac.uk/.
United States Geological Survey - Environment
     http://www.usgs.gov/environment/index.html
United Nations Environment Programme
     Frontpage is at href=http://www.unep.ch. The main RS/GIS related
     information is in the Global Resource Information Database (GRID) at sites
     including http://www.grid.unep.ch/gridhome.html, http://www.grida.no/ and
     http://www.inpe.br/grid/home

------------------------------

Subject: Using imagery during Natural (and other) disasters.

Can satellite imagery be used to watch newsworthy events?

Earthquakes, floods, volcanos, mega-icebergs, pollution disasters...
There is imagery for all of them! Watch relevant newsgroups as news of a
disaster breaks.
That's not to say there is immediate and extensive coverage of every possible
event: the satellites capable of imaging it may not be in the right place at
the right time! However, systematic programmes exist; notably the ESA/Eurimage
Earthwatch program at http://www.eurimage.it/Earth_Watching/Earth_Watching.html
(formerly listed at http://gds.esrin.esa.it/CSacquisitions which is still
valid)

------------------------------

Subject: Jobs

Where can I advertise or look for a job in Remote Sensing?

Note: there is a very high percentage of duplication between these sources!

   * The University of Minnesota's GIS Jobs Clearinghouse at
     http://www.gis.umn.edu/rsgisinfo/jobs.html. A good one-stop shop, with the
     best list of pointers to other sources you'll find anywhere.
   * The GIS-JOBS list at gopher://nisp.ncl.ac.uk:70/11/lists/gis-jobs
   * SPIE's Employment Service, at
     http://www.spie.org/web/employment/employ_home.html
   * The GEOSCI-JOBS and MET-JOBS listserv. Send subscription requests (for
     both lists) to listproc@eskimo.com. You will recieve details on how to
     post to the list, and guidelines for what is appropriate. Either full
     (each job mailed separately) or digest (weekly list) forms are available:

             subscribe geosci-jobs-digest / met-jobs-digest (digest)
     or      subscribe geosci-jobs / met-jobs                (full)

   * Geographic Designs, Inc, are an agency specialising in RS/GIS.
     http://www.geodesigns.com/
   * GeoSearch, Inc are at http://www.geosearch.com/
   * The GeoWeb Jobs Page http://www.ggrweb.com/job.html.
   * SDCSC Jobs Page

In addition to the above, comp.infosystems.gis tolerates a certain range of job
postings. Please read the detailed guidelines in that group's FAQ before
posting.

-------------------------------------------------------------------------------

------------------------------

Subject: Online Services Exchanges / Trade Fairs

WWW Information and Services Exchanges

The following interactive web sites are perhaps best described as 'trade
fairs':

   * European Wide Service Exchange http://ewse.ceo.org/
   * GeoWeb http://www.ggrweb.com/

A similar but non-interactive site is

   * The Geo Exchange http://giant. mindlink.net/geo_exchange

------------------------------

Subject: Software + hardware

Software + hardware

Here's a complete cop-out: software is rather well covered in related
documents.

Where can I find Descriptions/Reviews of Remote Sensing Software?

There is an excellect collection of reviews maintained by Oliver Weatherbee at
http://triton.cms.udel.edu:80/~oliver/gis_gip/gis_gip_list.html. In spite of
the "gislist" name, this deals extensively with Remote Sensing and Image
Processing software. Furthermore, comments and reviews are generally
independent of the manufacturers/distributors.

Is there a list of Software Vendors?

Where can I find information on Software Packages?

These questions are covered in the comp.infosystems.gis FAQ and the "Using the
Web for Geoscience Resources" FAQ, among others.

What software is available in the Public Domain?

See the Public Domain Cartographic Software FAQ.

Pointers to the FAQs are here.

Free packages for image processing include:

   * Khoros, from ftp://ftp.khoros.unm.edu/ / http://www.khoros.unm.edu/ or
     (supposedly)
     http://www.infc.ulst.ac.uk:80/informatics/research/vision/khoros/
   * Grass, from ftp://moon.cecer.army.mil/

A few more listed FYI with no comment (in all but one case, simply because I
know nothing):

   *  http://dcz.gso.uri.edu/XBrowse/browse/browse.html XBrowse- A
     client-server browse application for satellite AVHRR imagery.
   * Land Analysis System, from USGS/EDC (Landsat TM & NOAA AVHRR)
   *  http://www.atmos.washington.edu/gcg/SV.man/SVmanual.html Satview
     (University of Washington).

How can I recieve imagery on my PC?

This question is dealt with in detail in the WXSAT FAQ and other documents at
ftp://kestrel.umd.edu/pub/wxsat/docs/


------------------------------

Subject: Standards

Standards Committee

Committee on Earth Observations Satellites (CEOS)

I hope reproducing this paragraph isn't violating copyright - anyone? It comes
from too many sources to attribute!

CEOS was created in 1984 as a result of the international Economic Summit of
Industrialized Nations and serves as the focal point for international
coordination of space-related, Earth observation activities. Policy and
technical issues of common interest related to the whole spectrum of Earth
observation satellite missions and data received from such are addressed. CEOS
encourages complementarity and compatibility among space-borne Earth observing
systems through coordination in mission planning, promotion of full and
non-discriminatory data access, setting of data product standards, and
development of compatible data products, services, and applications. The user
community benefits directly from this international coordination.

The CEOS information system is at http://gds.esrin.esa.it/CCEOSinfo, and
contains full details and CEOS files.

See also CEOS calibration pages at
http://southport.jpl.nasa.gov/calceos/calceos.html

CEOS also sponsors

The CEOS International Directory Network (CEOS IDN)

Need someone to wirte a real entry This is the authoritative worldwide
information system that answers every possible question about Satellite Earth
Observation. The complete database is held at the three coordinating nodes in
America (NASA/GSFC), Europe (ESA/ESRIN) and Asia (NASDA/EOC). For access
details, see under Further Information.

------------------------------

Subject: Copyright

How does Copyright affect Satellite Imagery?

Wim Bakker recently supplied the following article, in part a translation from
a (Dutch) NLR article. I have taken the liberty of cutting it down somewhat.

I understand the issue of copyright on satellite imagery may in fact vary
significantly depending on what country you're in. Mark Goodman
(Mark_Goodman@achre.gov) writing from a US point of view comments:

     I'm not sure that satellite imagery is covered by copyright law. It
     may depend on what country you're in. I believe that SPOT and EOSAT
     protect their intellectual property rights through trade secrets
     laws, and through restrictive sales contracts that prohibit
     redistribution of raw data, even for scientific use!

Your mileage may vary!

) Copyright

There is a lot of confusion about the copyright connected to the use of
satellite images and everything related to this.

According to Websters dictionary "copyright" is

  1.  copy.right \-.r{i-}t\ n : the exclusive legal right to reproduce,
     publish, and sell the matter and form of a literary, musical, or artistic
     work - copyright aj

  2.  copyright vt : to secure a copyright on

In 1886, during the Convention of Bern the matter of copyright was regulated
internationally. It states that the author (creator) of a certain matter
remains the owner of his product. This also means that if you buy a copyrighted
product you pay for the use of this product and you can never claim to be the
owner of such a product. Furthermore, you can never claim any other rights
about such a product (e.g. the right to reproduce the product).

In copyright the following 5 stages can be distinguished:

  1. the creation of a product
  2. the manufacturing of a product
  3. the distribution of a product
  4. the use of a product
  5. the reproduction of a product

These 5 points can also be distinguished with the use of satellite images. Two
operational Earth observing satellites will be described here: Landsat and
SPOT.

Here I have cut a detailed description of Landsat and SPOT distribution, as
being (IMHO) too detailed for this FAQ - NK.

Now when does the copyright principle touch the user?
Only when the user reproduces or copies (point 5) the satellite images is he
affected by the copyright issue. At all times the user must be aware of the
owner/producer of the data. The owner/producer may or may not permit the
reproduction of the datas, but must in any case be mentioned on all
publications of satellite images!
Note: the following details may vary in different parts of the world, although
the principles apply in any case.
For SPOT data this will be CNES; for Landsat data received by European ground
stations this will be ESA; and for Landsat data from America this will be EOSAT
(or NOAA and EROS Data Center (EDC) for old data).

The owner/producer indicates which reproductions are allowed. The reproduction
of raw data - copying CCT's and film - is never allowed and for other
categories that are allowed the owner will ask for a certain contribution for
the right to reproduce the data; this is called the reproduction fee.

The following reproductions are free of reproduction fee

   * Posters, slides, advertisement or publications used for conferences,
     meetings, symposiums and exhibitions in the field of Remote Sensing.
   * Technical reports of RS conferences, symposiums etc.
   * Scientific reports and papers

For the following, a reproduction fee is due:

   * Newspapers
   * Magazines
   * Brochures
   * Books not related to the field of RS
   * Posters, either ones that are sold as well as free copies
   * Calendars
   * Atlasses
   * Postcards and invitations
   * Using images on TV and video

At all times the owner/producer must be mentioned on the reproductions, even if
no reproduction fee is due!
This can be done in two ways

  1. To use the word copyright followed by the owner/producer and the year of
     production. E.g.
     Copyright ESA 1988

  2. To use the international sign for copyright ) followed by the
     owner/producer and the year of production. E.g.
     ) CNES/NLR 1994
     In the last example the NLR could have processed data from SPOT.

Conclusion

   * For some (scientific) applications you owe no reproduction fee.
   * At all times the owner/producer must be mentioned on reproductions using
     the word copyright or the sign )
   * In case of doubt, ask your distributor!
