LIMA Products Zipfile Content README Table of Contents INTRODUCTION PART 1: PRODUCTS AVAILABLE Part 2: FILE NAMING CONVENTION PART 3: CONTENTS OF ZIPFILE PART 4: DISTRIBUTION INFORMATION PART 5: PROJECT RESOURCE INFORMATION INTRODUCTION: In support of the International Polar Year (IPY 2007-2008), Landsat Imagery Mosaic Antarctica (LIMA) brings the coldest continent on Earth alive in greater detail than ever before through this virtually cloudless, seamless, and high resolution satellite view of Antarctica. The U.S. Geological Survey (USGS), the British Antarctic Survey (BAS), and the National Aeronautics and Space Administration (NASA), with funding from the National Science Foundation (NSF), created LIMA from more than 1,000 Landsat ETM+ scenes. The Landsat Image Mosaic of Antarctica (LIMA) is seamless and virtually cloudless. LIMA is the most geometrically accurate (within a pixel—30 meters by 30 meters of land) mosaic of Antarctica and has the highest spatial resolution. As the first major scientific outcome of the IPY, LIMA truly fulfills the IPY goals. LIMA is an international effort, supports current scientific polar research, encourages new projects, and helps the general public visualize Antarctica and changes happening to this southernmost environment. Researchers and the general public can download LIMA and all of the component Landsat scenes at no charge. PART 1: PRODUCTS AVAILABLE Created from over 1,000 Landsat 7 ETM+ scenes, LIMA products consists of two principle mosaics and six stretched versions. Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) The Natural-Color, Pan-Sharpened LIMA combines Landsat ETM+ bands 3, 2, and 1 (red, green, and blue of the electromagnetic spectrum) at 30-m spatial resolution with the 15-m, grayscale panchromatic band 8. Pan-sharpening maintains the natural-color information valuable for field recognition in Antarctica, but with the higher spatial resolution, features in the snow and ice will appear more clearly defined. Through resampling techniques, each pixel in the 30-m, natural-color bands is divided into four smaller pixels and then merged precisely with the pixels in the 15-m panchromatic band. With each pixel representing 15 m by 15 m (49 ft by 49 ft), scientists can identify features roughly the size of half a basketball court. False-Color, Pan-Sharpened LIMA (bands 4, 3, 2) The False-Color, Pan-Sharpened LIMA incorporates infrared data, allowing scientists to more clearly discriminate between ice and snow. This version merges Landsat ETM+ bands 4, 3, and 2 (near-infrared, red, and green of the electromagnetic spectrum) at 30-m spatial resolution with the 15-m, grayscale panchromatic band 8. Pan-sharpening maintains the false-color information but with the higher spatial resolution, features in the snow and ice will appear more clearly defined. Through resampling techniques, each pixel in the 30-m, false-color bands is divided into four smaller pixels and then merged precisely with the pixels in the 15-m panchromatic band. With each pixel representing 15 m by 15 m (49 ft by 49 ft), scientists can identify features roughly the size of half a basketball court. Enhanced Versions of LIMA Both the natural-color and false-color, pan-sharpened versions of LIMA are available in different stretches to bring out features in Antarctica that would not normally be visible because of the high reflectance of snow and ice. In the same way that sunglasses soften the glare, these enhancements tone down the brightness of the entire image while preserving the color balance. 1x Stretch slightly darkens all of the mosaic to reveal areas of highest reflectance, such as snow-covered slopes that face the sun. 3x, 10x, and 30x Stretches reveal features on the surface of the relatively flat ice sheet. By degrees they darken the areas of highest reflectance to reveal very subtle variations in the ice sheet, while areas of lower reflectance lose details and become darker, even black. The 3x Stretch still preserves some of the features in the darker areas. For example, the 3x Stretch reveals ice flow features without blackening out the rocks. The 10x and 30x Stretches show features that indicate the direction of the ice flow and flow irregularities on the ice sheet in the areas of highest reflectance, blackening out most other areas. PART 2: FILE NAMING CONVENTION The file naming convention for the LIMA Product zipfile is as follows: [Dataset]_[TileID] Dataset = Indicates the LIMA zipped product List of LIMA Zipped Products RGBREF = Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) RGB1X = Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) with 1X stretch applied RGB3X = Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) with 3X stretch applied RGB10X = Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) with 10X stretch applied RGB30X = Natural-Color, Pan-Sharpened LIMA (bands 3, 2, 1) with 30X stretch applied CIRREF = False-Color, Pan-Sharpened LIMA (bands 4, 3, 2) CIR1X = False-Color, Pan-Sharpened LIMA (bands 4, 3, 2) with 1X stretch applied CIR3X = False-Color, Pan-Sharpened LIMA (bands 4, 3, 2) with 3X stretch applied MOS = 16 bit Intermediate LIMA (bands 4, 3, 2, 1) TiledID = Lower left WGS84 Antarctic Polar Stereographic corner coordinate Example: CIR1X_x+1350000yy+1500000 CIR1X = False-Color, Pan-Sharpened LIMA (bands 4, 3, 2) with 1X stretch applied x+1350000y+1500000 = Lower left WGS84 Antarctic Polar Stereographic corner coordinate. Lower left corner is +1350000m in the x direction from the pole. Lower left corner is +1500000m in the y direction. PART 3: CONTENTS OF ZIPFILE .tif = Full Resolution Geotiff image .tfw = World file for full resolution Geotiff image .aux = Full Resolution Support File .prj = Projection File .jpg = Lossy compressed image .jpw = World file for lossy compressed image .xml = FGDC Metadata file .htm = HTML format FGDC metadata file suitable for reading and printing Shapefile (.dbf, .prj, .sbn, .sbx, .shp, .shx) = The shapefile (consisting of 6 files) represents the tiled download grid. LIMAReadme.txt = The readme text file PART 4: DISTRIBUTION INFORMATION Data is accessible through http://lima.usgs.gov Also available for download are one center-filled mosaic, the original NLAPS Landsat scenes, the processed Landsat scenes, MODIS Mosaic of Antarctica, and the RADARSAT Image Map of Antarctica. Access points (i.e. map interface, kml) can be found at: http://gisdata.usgs.gov To acquire entire datasets via Bulk Data Distribution email bulkdatainfo@usgs.gov PART 5: PROJECT RESOURCE INFORMATION http://lima.usgs.gov http://lima.nasa.gov/ http://www.discoveringantarctica.org.uk/ http://nsidc.org/ipy/ Disclaimer: Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U. S. Government. Publication Date: April 2009