TerraColor® Global Landsat Data Specifications
The primary source imagery used to create TerraColor Global is from the Landsat 7 (ETM+) satellite, and about 75% of areas are produced with scenes from the GeoCover Landsat imagery database. (The Landsat scenes in GeoCover were later re-processed and replaced by GLS2000.) In the last several years, Earthstar Geographics has re-processed many areas using imagery from the Landsat 8 and EO-1 satellites to improve upon the GLS2000 scene set. TerraColor is therefore a hybrid product produced from multiple sources. (For more detailed information on upgrades made to the TerraColor product click here.) The specifications below outline some key technical information about the product.
- Year of data acquisition - Primarily year 2000, with some scenes from 1999, 2001 to 2003. Many smaller tropical islands have been re-processed with newer EO-1 ALI satellite imagery, and some areas (such as the Philippines, Okinawa, Franz Josef Land, and others) were re-processed using new 2013-2014 Landsat 8 imagery.
- Registration accuracy - All Landsat scenes used as input to the mosaic products were orthorectified using the best geodetic control and elevation data available to the US government. The products have been verified to have absolute positional accuracies of +/- 50 meters RMSE, with RMSEs under 25 meters validated in many parts of the world. (The only exception to these accuracies may be some very remote polar islands where precise ground control is not available. These islands were usually absent from the GeoCover/GLS2000 Landsat set.)
- Cloud cover - 90% of the source Landsat scenes used in the GeoCover/GLS2000 set have less than 10% cloud cover. Cloud cover is heaviest over equatorial tropical areas, while temperate regions can be up to 99% cloud free in some areas. (Earthstar Geographics has made a concerted effort to improve upon the 10% of scenes with greater cloud cover, so TerraColor has far less cloud cover in typically cloudy areas than products made solely with the GeoCover/GLS2000 Landsat set.)
- Data quality - Overall data quality is excellent, but occasional errors inherent to the Landsat sensor (scan line errors, etc.) can be found in some areas. The imagery is virtually seamless for the most part due to use of sophisticated contrast adjustment and edge feathering algorithms, and use of scenes from the growing season where possible.
TerraColor® NextGen Landsat 8 Data Specifications
The primary source imagery used to create TerraColor NextGen is from the Operational Land Imager (OLI) sensor onboard the US Landsat 8 satellite. All scenes were hand selected by Earthstar Geographics for quality, seasonal match and other factors. The specifications below outline some key technical information about the product. (For detailed technical information, visit the USGS Landsat 8 website.)
- Year of data acquisition - Primarily years 2014 and 2015 with a few scenes from 2013.
- Registration accuracy - 12 meter circular error, 90% confidence global accuracy for OLI.
- Cloud cover - Varies depending on the part of the world. Scenes in desert areas usually have <1% cloud cover, scenes in other areas may have more (but usually <5%).
- Data quality - Overall data quality from the Landsat 8 OLI sensor is excellent. Scenes are selected based on quality, cloud cover, seasonal match and other factors.