The Color Shaded Relief of Alaska map layer is a 100-meter resolution color-sliced elevation image of Alaska, with relief shading added to accentuate terrain features, in an Albers Equal-Area Conic projection. The image was produced by combining the 100-meter resolution color-sliced elevation and the grayscale shaded relief data sets that are distributed by the National Atlas of the United States. The color shaded relief data were derived from the National Atlas 100-meter resolution elevation data. The 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 of the National Atlas of the United States. The 100-meter resolution color shaded relief 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 Shaded Relief of Alaska. National Atlas of the United States. Available at: http://purl.stanford.edu/yw041vw3863. The Color Shaded Relief data set was created as a combination of the 100-meter resolution color-sliced elevation image and the grayscale shaded relief image of the same area, both of which are also distributed separately by the National Atlas. Development of those data sets is described in their respective metadata. Included with the GeoTIFF are an information file (.xml), an auxiliary information file (.aux.xml), an image overview file (.ovr), 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 >-3326950.0 >2437950.0 The projection (.prj) file contains the following information: > PROJCS["Albers_NAD83_Alaska", >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",-154.0], >PARAMETER["Standard_Parallel_1",55.0], >PARAMETER["Standard_Parallel_2",65.0], >PARAMETER["Latitude_Of_Origin",50.0], >UNIT["Meter",1.0]] Data set extent in meters (Albers Equal-Area Conic projection) >North 2438000 >West -3327000 >East 1654000 >South 346000 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.
