Landsat

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Revision as of 18:53, 22 October 2005

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LandSat 7 is a satellite of the USGS Landsat Project. The satellite is equiped with an ETM+ instrument that is an eight-band multispectral scanning radiometer capable of providing moderate resolution image data of the Earth's surface.

The band information is combined to produce an image, and by using different bands you can get images that represent human eye perception, thermal, infrared or other visuals.

LandSat 7 data is available globally at a scale where you can pick out many prominent features in the landmass. The maximum resolution of the ETM+ is 15 meters per pixel on the panchromatic band.

Contents

NLT

NLT Visible highest resolution
NLT Visible highest resolution

NASA Learning Technologies has processed the LandSat 7 data to create their own imagery. Pan-sharpening the images was planned, however other priorities mean that 30 meters will be the maximum resolution for the forseeable future. See NLT Landsat Processing Techniques for information on how the data was processed, and NLT Data Issues for known issues.

Visible

  • The maximum resolution is 30 m per pixel.
  • Uses bands 3, 2, 1

Pseudo

  • The maximum resolution is 30 m per pixel.

Geocover

GeoCover 2000 highest resolution
GeoCover 2000 highest resolution

Geocover is a product of MDA Federal (formerly EarthSat), and is pseudo color Landsat imagery. The 1990 data was aquired with LandSat 5, and the 2000 data with LandSat 7's ETM+.

2000

  • The maximum resolution is 15 m per pixel.
  • Uses bands 7, 4, 2

1990

  • The maximum resolution is 30 m per pixel.
  • Uses bands 7, 4, 2

OnEarth

OnEarth Visible highest resolution
OnEarth Visible highest resolution

OnEarth is a project of the NASA Jet Propulsion Laboratory. OnEarth has asked that World Wind not access the imagery off its servers. This data is available in World Wind as Community Landsat 7.

Visible

  • The maximum resolution is 15 m per pixel.
  • Uses bands 3, 2, 1

Pseudo

  • The maximum resolution is 15 m per pixel.
  • Uses bands 5, 4, 2.

Data Acquisition

Landsat 7 only gets one chance every 16 days to cover any given area. If there are clouds, fog, smog, snow on the ground (too white), too much grass on the ground (too green), too low or too high sun angle (low contrast), satellite maintenance, solar storm, etc, that chance is lost. A few bad takes in a row, and a whole year is lost. A scene is 160x180km, and a perfect scene has to have perfect conditions for the whole area.

Landsat 7 was launched in 1999 and now it has some data quality problems. No replacement/equivalent satellite is planned, at least not an inexpensive, US funded one!

The LandSat 7 data will be the best available global images for quite a while, and the fact that they are free and available on the net makes them even more significant.

External Link

An Introductory Landsat Tutorial

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