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| Earth Resources Observation and Science (EROS) |
Tri-Decadal Global Landsat Orthorectified Overview
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Tri-Decadal Global Landsat Orthorectified ETM+ image |
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back to Satellite Product List Product DescriptionThe Tri-Decadal Global Landsat Orthorectified data collection (formerly Landsat Orthorectified) consists of approximately 7,500 Landsat Multispectral Scanner (MSS, Landsat 1-5) images, 7,461 Landsat Thematic Mapper (TM, Landsat 4-5) images and approximately 8,500 Landsat Enhanced Thematic Mapper Plus (ETM+, Landsat 7) images, which were selected to provide full sets of global coverage over three time periods: circa 1975, circa 1990, and circa 2000. MSS was carried onboard Landsats 1-5, TM on Landsats 4-5, and ETM+ on Landsat 7. All selected images are either cloud-free or contain minimal cloud cover, and have a high quality ranking with regard to the possible presence of errors such as missing scans or saturated bands. Two data products are currently offered:
Landsat MSS, TM, and ETM+ data were orthorectified, using geodetic and elevation control data to correct for positional accuracy and relief displacement. Large blocks of Landsat data were adjusted through a patented procedure that uses pixel correlation to acquire tie-points within the overlap area between adjacent images. Ground control points are fixed, and images have been registered to the Universal Transverse Mercator (UTM) map projection and coordinate system and the World Geodetic System 1984 (WGS84) datum. All image bands have been individually resampled, using a nearest neighbor algorithm. Positional accuracy on the final image product has a Root Mean Square Error of better than 100 meters (MSS) and 50 meters (TM and ETM+). The Landsat data were acquired and processed through a National Aeronautics and Space Administration (NASA) contract with Earth Satellite Corporation, Rockville, Maryland, and are part of NASA's Scientific Data Purchase program. When possible, data were collected when vegetation was at peak greenness. Peak greenness was determined from global 1-kilometer Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) data. When peak greenness data were not available, images from other times of the year were substituted. For pricing and further information about the individual data products, see the Tri-Decadal Global Landsat Orthorectified Single Scene and Tri-Decadal Global Landsat Orthorectified Mosaics webpages.
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