This layer is a georeferenced raster image displaying color-sliced elevation data for Puerto Rico and the U.S. Virgin Islands at 100-meter resolution, using an Albers Equal-Area Conic projection. Each color tint represents a range of elevation values. There are 32 elevation classes and colors required to map all 50 of the United States, Puerto Rico, and the U.S. Virgin Islands, plus an additional class and color to represent non-U.S. land. The Puerto Rico and the U.S. Virgin Islands map layer contains elevation classes 1 to 18, as well as class 33 (non-U.S. land). The color-sliced elevation data were derived from National Elevation Dataset (NED) data and show the terrain of the conterminous United States at a resolution of 100 meters. The NED is a raster product assembled by the U.S. Geological Survey, designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections made in the NED assembly process minimize artifacts, permit edge matching, and fill sliver areas of missing data. This layer is part of the 1997-2014 edition National Atlas of the United States. The 100-meter resolution color-sliced elevation data were developed to portray the terrain of the United States at 1:1,000,000 scale. They are intended primarily for visual purposes. The original NED data should be used for conducting analysis and determining the most accurate elevation values. No responsibility is assumed by the National Atlas of the United States in the use of these data. National Atlas of the United States. (2013). 100-Meter Resolution Color-Sliced Elevation of Puerto Rico and the U.S. Virgin Islands. National Atlas of the United States. Available at: http://purl.stanford.edu/yr618vd2453. Color-sliced elevation is a classification into 32 steps and colors of the 100-meter Elevation data set that is distributed by the National Atlas of the United States. Characteristics and development of the Elevation data are described in the metadata for that data set. The following table describes the elevation limits of each step, the color index value associated with the step, and the red, green, and blue (RGB) values used to display the step in online National Atlas applications. >From, To Color Index Red Green Blue Comments >Elevation Elevation >---------------------------------------------------------------------------------------- >-100 -1 1 178 178 178 Below sea level >0 0 2 193 224 250 Oceans >1 50 3 66 143 150 >51 100 4 82 154 156 >101 150 5 95 161 158 >151 200 6 109 168 160 >201 300 7 123 176 164 >301 400 8 136 184 167 >401 500 9 149 191 169 >501 600 10 161 199 171 >601 700 11 178 209 176 >701 800 12 191 217 178 >801 900 13 207 227 182 >901 1000 14 221 235 185 >1001 1100 15 234 242 187 >1101 1200 16 250 252 189 >1201 1300 17 252 249 184 >1301 1400 18 245 234 171 >1401 1500 19 240 222 158 >1501 1600 20 235 211 148 >1601 1700 21 227 198 136 >1701 1900 22 222 188 124 >1901 2100 23 214 176 114 >2101 2300 24 209 165 102 >2301 2500 25 201 152 91 >2501 2700 26 196 143 82 >2701 2900 27 189 133 74 >2901 3200 28 181 122 63 >3201 3700 29 176 113 55 >3701 4200 30 168 103 45 >4201 5200 31 163 95 39 >5201 6200 32 156 85 31 >n/a n/a 33 240 235 211 non-U.S. land > CMY color equivalents are available on request. The minimum and maximum elevation values listed below come from the National Atlas of the United States 100-meter resolution Elevation map layer. Values were derived from the National Elevation Dataset, but should not be considered authoritative elevations of any specific features. > > Region Minimum elevation Maximum elevation >------------------------------------------------------------------------ > Alaska 12 6167 > Hawaii -3 4402 > Conterminous U.S. -86 4193 > PR and VI -6 1322 Included with the GeoTIFF are a reclass table (.txt), a color ramp file (.clr), a Photoshop color table (.act), an information file (.xml), an auxiliary information file (.aux.xml), an image overview file (.ovr), a value attribute database file (.vat.dbf), a .tfw file (more information included below), and a .prj file (more information included below.) The contents of the associated world file (.tfw) are: >100.0 >0.0 >0.0 >-100.0 >-195950.0 >437950.0 The projection (.prj) file contains the following information: > PROJCS["Albers_NAD83_ PRVI ", >GEOGCS["GCS_North_American_1983", >DATUM["D_North_American_1983", >SPHEROID["GRS_1980",6378137.0,298.257222101]], >PRIMEM["Greenwich",0.0], >UNIT["Degree",0.0174532925199433]], >PROJECTION["Albers"], >PARAMETER["False_Easting",0.0], >PARAMETER["False_Northing",0.0], >PARAMETER["Central_Meridian",-66.5], >PARAMETER["Standard_Parallel_1",8.0], >PARAMETER["Standard_Parallel_2",18.0], >PARAMETER["Latitude_Of_Origin",15.0], >UNIT["Meter",1.0]] Data set extent in meters (Albers Equal-Area Conic projection) >North 438000 >West -196000 >East 286000 >South 230000 There are no NULL or NODATA values in the GeoTIFF. Instead, all elevation values in oceans have been set to zero as part of the masking process. Information about National Atlas Web services can be found on the Web Map and Web Feature Services page; see <http://nationalatlas.gov/infodocs/webservices.html>. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.