Digital imagery can greatly enhance a GIS. Imagery is a powerful visual aid and serves as a source of derivative information such as planimetrics and classification schemes to derive such information as land use or vegetation. If your GIS covers a particularly large area, aerial imagery may not be a practical or economical choice. Satellite imagery is often the preferred choice of imagery for larger regions. More and more choices of satellite imagery are becoming available and the cost associated with its purchase is dropping.

Listed here are some of the most prominent sources of currently available satellite imagery and future satellite launches. This guide is meant to be a launching point for searching for and acquiring information about available satellite imagery. Individual choice of imagery will depends on many factors such as resolution, image type and cost.

Many of the imagery can be purchased directly from the associated agencies. In addition, there are online sites that also specialize in satellite imagery sales. Plangraphics is a reseller of Space Imaging’s IKONOS imagery. EOMOnline sells several imagery such as Landsat 5, IRS Imagery and Landsat 7. Terraserver is also a well-known source of satellite imagery.

Here are some basic satellite imagery related terms that are useful:

Hyperspectral imagery

Useful for classifying material types on the Earth’s surface – beneficial in agriculture and forestry management, mineral exploration, environmental monitoring and national security activities.

Interval

Amount of time that passes before the satellite scans the same point of the globe.

Multispectral

Two or more images taken simultaneously, but each image taken in a different part of the electromagnetic spectrum.

Panchromatic

Imagery taken of all wavelengths within the visible spectrum, though not uniformly.

Orbit

The act of circling the earth. The type of orbit describes the path the satellite takes as it circles the earth.

Resolution

The amount of ground covered in one pixel of the image. For example an image with one meter resolution means that each pixel in the image represents one square meter on the ground. Click here for examples of imagery at different resolutions.

Sun-synchronous

An orbit that always passes over the earth at the same local sun time.

Swath

Amount of ground covered lengthwise in the passing of the satellite.

Satellite imagery

Satellite:	IKONOS 2	Imagery:	IKONOS
Launch Date:	24, September, 1999	Country:	USA
Agency:	Space Imaging
Swath:	11 km	Orbit:	Sun-synchronous
Intervals	2-4 Days	Resolution:	1 m panchromatic 4 m multispectral 1 m fused*

*one-meter fused panchromatic and multispectral resolution.

Satellite:	Orbview-4	Imagery:	Orbview-4
Launch Date:		Country:	USA
Agency:
Swath:	5 – 8 km	Orbit:
Intervals	~ 3 days	Resolution:	1 meter panchromatic 4 meter multispectral 8/20 meter hyperspectral

Satellite:	Orbimage	Imagery:	Orbview-3
Launch Date:	First Quarter 2001 (initially set for 1999)	Country:	USA
Agency:	Orbimage
Swath:	8 km	Orbit:
Intervals	~3 days	Resolution:	1 & 2 m panchromatic 4 m multispectral

Satellite:	Orbimage	Imagery:	Orbview-2
Launch Date:	August 1997	Country:
Agency:	Orbimage
Swath:	2,800 km	Orbit:
Intervals		Resolution:	1 km multispectral imagery eight spectral bands, six in the visible and two in the near-infrared spectrum.

Satellite:		Imagery:	EROS-A Series
Launch Date:	December 5, 2000 (initially set for late 1999) EROS A2 – 3rd quarter of year 2001	Country:	Israel
Agency:	ImageSat International (formerly West Indian Space)
Swath:	12.5 km	Orbit:	Polar, sun-synchronous

Satellite:		Imagery: EROS-B	EROS B Series
Launch Date:	EROS B1 – 2nd quarter of year 2002 EROS B2 – 4th quarter of year 2002 EROS B3 – 2nd quarter of year 2003 EROS B4 – 4th quarter of year 2003 EROS B5 – 2nd quarter of year 2004 EROS B6 – 4th quarter of year 2004	Country:	Israel
Agency:	Israel Aircraft Industries Core Software Technologies
Swath:	16 km	Orbit:
Intervals	1 day	Resolution:

Satellite:	Advanced Land Observing Satellite (ALOS)	Imagery:	PRISM
Launch Date:	August 2002	Country:	Japan
Agency:
Swath:	35 km	Orbit:	Sun-Synchronous
Intervals	46 days	Resolution:	2.5 meters panchromatic

Satellite:		Imagery:	KVR-1000 (SPIN-2)
Launch Date:	1987	Country:	Russia
Agency:	Russian Space Agency (Sovinformsputnik)
Swath:	2/10/40 km	Orbit:
Intervals		Resolution:	2-3 meters panchromatic

Satellite:	IRS-1C & IRS-1D	Imagery:	LISS
Launch Date:		Country:
Agency:	Indian Space Agency
Swath:	70 km	Orbit:
Intervals	5 days	Resolution:	5.8 meter panchromatic

Satellite:	Resurs-01	Imagery:	MSU-SK/ MSU-E
Launch Date:	October 1994 – Resurs-01-3 July 1998 – Resurs-01-4	Country:	Russia
Agency:
Swath:		Orbit:	Polar sun-synchronous
Intervals		Resolution:

Satellite:	Landsat 7	Imagery:	Enhanced Thematic Mapper Plus
Launch Date:	April 15, 1999	Country:	USA
Agency:	Originally NASA – USGS recently assumed responsibility.
Swath:	185 km	Orbit:	Near-polar, sun-synchronous
Intervals	16 days	Resolution:	30 meters 8-band multispectral 15 meters 1-band panchromatic

Satellite:	Landsat 5	Imagery:	Thematic Mapper (TM)
Launch Date:	March 1, 1984	Country:
Agency:
Swath:	185 km	Orbit:	Polar, sun-synchronous
Intervals	16 days	Resolution:	30 meters (except band 6 (thermal) – 120 meters)

Satellite:	NOAA-12	Imagery:	AVHRR
Launch Date:	May 14, 1991	Country:	USA
Agency:	NOAA
Swath:	2399 km	Orbit:	Polar orbit, near circular
Intervals	14 times/day Where is it right now?	Resolution:	1.1 km

Satellite:	SPOT	Imagery:	SPOT Image
Launch Date:	Spot 1 – February 22, 1986 Spot 2 – January 22, 1990 Spot 3 – September 26, 1993 Spot 4 – March 24, 1998 Spot 5 – 2002	Country:	France
Agency:	Spot	Coverage:	87° N to 87° S (lat.)
Swath:	900 km	Orbit:	polar, circular, sun-synchronous
Intervals	26 days	Resolution:

Satellite:	RADARSAT-2	Imagery:
Launch Date:	2003	Country:	Canada
Agency:	Canadian Space Agency (CSA) and MacDonald Dettwiler
Swath:	20, 100 and 500 km	Orbit:	sun-synchronous circular orbit
Intervals	3 days	Resolution:	2, 28 and 300 meters high-resolution multi-polarized imagery