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Orthorectified Landsat Enhanced Thematic Mapper (ETM+) Compressed Mosaics
Mosaic Product Specifications:
Spectral Bands: Three Landsat ETM+ bands, each sharpened with the panchromatic band.
Band 7 (mid-infrared light) is displayed as red
Band 4 (near-infrared light) is displayed as green
Band 2 (visible green light) is displayed as blue
Coverage: The GeoCover Landsat mosaics are delivered in a Universal Transverse Mercator (UTM) / World Geodetic System 1984 (WGS84) projection. The mosaics extend north-south over 5 degrees of latitude, and span east-west for the full width of the UTM zone. For mosaics below 60 degrees north latitude, the width of the mosaic is the standard UTM zone width of 6 degrees of longitude. For mosaics above 60 degrees of latitude, the UTM zone is widened to 12 degrees, centered on the standard even-numbered UTM meridians. To insure overlap between adjacent UTM zones, each mosaic extends for at least 50 kilometers to the east and west, and 1 kilometer to the north and south.
Pixel size: 14.25 meters,
Contrast Enhancement: In order to maximize the information of each mosaic, EarthSat has applied a company proprietary contrast stretch known as LOCAL (Locally Optimized Continuously Adjusted Look-up-tables) stretch. This stretch uses multiple, locally collected histograms, to create a radiometrically seamless blend of contrast adjustment across areas of potentially extreme contrast ranges. The suffix “__loc” is added to the mosaic name to signify the application of the LOCAL stretch.
Absolute Positional Accuracy: ±75 (ROSE: I am comfortable with a 50 meter RMSE, but wouldn’t want to override your V&V folks) meters RMSEr.
File Naming Convention: Within each UTM zone the “partitions” extend from the equator to the north and south (in the northern and southern hemisphere respectively) in 5 degree increments. The naming convention for the mosaics is comprised of three components, separated by hyphens; the first element is the hemisphere (either N or S), the second is the UTM zone number (1-60), the last element is the latitude of the southern edge of the mosaic in the northern hemisphere and the northern edge of the mosaic in the southern hemisphere.
For example:
N-13-25_2000_loc: names a LOCAL stretched mosaic partition in the northern hemisphere, in UTM zone 13, extending between 25 and 30 degrees north latitude.
S-21-10_2000_loc names a LOCAL stretched mosaic partition in the southern hemisphere, in UTM zone 21, extending between 10 and 15 degrees south latitude.
Source (Input) Data:
Imagery:
Spectral Bands: Landsat ETM+ bands 7, 4, and 2,
Coverage: 5x6 degrees (south of 60 degrees North), and 5x12 degrees (north of 60 degrees North),
Projection/Datum: UTM / WGS84,
Pixel Size: Mixture of 14.25,
Interpolation Method: Cubic Convolution,
Orientation: North Up,
Coverage Date: Scene dependent (nominally 2000 +/- 3 years).
Control:
Horizontal: Image matching to 1990 GeoCover scenes where available, otherwise Landsat-7 ephemeris was used.
Vertical: DTM with 3-arc second postings, where available. Where 3-arc second data not available, GTOPO30 (30-arc second ) digital elevation models are used.
Digital Image Processing:
Mosaicing:
Radiometrically balanced across automatically collected seam lines.
Image Enhancements:
The data are spatially and spectrally unenhanced.
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