Each of the above CD-ROM series is organized differently, but within each series the organization is consistent. For example, the 1990 conterminous U.S. land cover characteristics data set CD-ROM consists of four directories and a readme.txt file:
source/ lcclass/ derived/ attrib/ readme.1st*Each of the first 3 directories contains image data (.img files) in 8-bit or 16-bit format. There are also a number of text files (found in the attrib/ directory) useful for describing the values found within each of these images. The images themselves are briefly described in the following table:
FILE TYPE SIZE RANGE DESCRIPTION -------------------------------------------------------------------------------------------- DIRECTORY: \SOURCE\IMAGES WATER.IMG 8-BIT 13251843 0-1 WATER BODIES DEM.IMG 16-BIT 26503686 0-14018 DIGITAL ELEVATION MODEL STLINE.IMG 8-BIT 13251843 0-255 STATE BOUNDARY LINES STPOLY.IMG 8-BIT 13251843 0-255 STATE FIPS POLYGONS CTYLINE.IMG 8-BIT 13251843 0-255 COUNTY BOUNDARY LINES CTYPOLY.IMG 16-BIT 26503686 0-3112 COUNTY POLYGONS NDVI90.IMG 8-BIT 106014744 0-200 8-CHANNEL SET OF 1990 NDVI 28-DAY COMPOSITE NDVIMAX.IMG 8-BIT 13251843 0-200 1990 MAXIMUM GREENNESS (NDVI) COMPOSITE MLRA.IMG 8-BIT 13251843 0-178 MAJOR LAND RESOURCE AREAS ECOREG.IMG 8-BIT 13251843 0-76 EPA ECOREGIONS LULC.IMG 8-BIT 13251843 0-91 USGS LAND USE AND LAND COVER SAMPLE FROST.IMG 16-BIT 26503686 0-348 FROST-FREE PERIOD DIRECTORY: \LCCLASS\IMAGES LCC71.IMG 8-BIT 13251843 0-71 PRELIMINARY LAND COVER REGIONS CLASSIFICATION LCC159.IMG 8-BIT 13251843 0-159 FINAL LAND COVER REGIONS CLASSIFICATION DIRECTORY: \DERIVED\IMAGES LCCUSGS.IMG 8-BIT 13251843 0-26 MODIFIED USGS LEVEL 2 LAND USE AND LAND COVER CLASSIFICATION LCCSIB.IMG 8-BIT 13251843 0-27 MODIFIED SIMPLE BIOSPHERE MODEL CLASSIFICATION LCCBATS.IMG 8-BIT 13251843 0-28 MODIFIED BIOSPHERE ATMOSPHERE TRANSFER SCHEME CLASSIFICATION ONSET.IMG 8-BIT 13251843 0-24 ONSET OF GREENNESS CLASSIFICATION PEAK.IMG 8-BIT 13251843 0-24 PEAK OF GREENNESS CLASSIFICATION LENGTH.IMG 8-BIT 13251843 0-255 DURATION OF GREENNESS CLASSIFICATION