Color Alaska Shaded Relief - 200-Meter Resolution, Albers projection

Metadata also available as

Frequently anticipated questions:


What does this data set describe?

Title:
Color Alaska Shaded Relief - 200-Meter Resolution, Albers projection
Abstract:
The color Alaska shaded relief data were derived from National Elevation Dataset (NED) data, and show the terrain of Alaska at a resolution of 200 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. The National Atlas also includes a Lambert Azimuthal Equal Area projection shaded relief file; this file is the same data in an Albers projection.
Supplemental_Information:
The associated world file is included as part of the GeoTIFF. The contents of the world file are:
200.0000
0.000000
0.000000
-200.0000
-3390900.0000
2449900.0000
The following projection file can be used when using ESRI's ArcGIS to view the GeoTIFF (any line breaks should be removed): PROJCS["Albers_NAD_1983_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]]
  1. How should this data set be cited?

    National Atlas of the United States, 200603, Color Alaska Shaded Relief - 200-Meter Resolution, Albers projection: National Atlas of the United States, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 167
    East_Bounding_Coordinate: -122
    North_Bounding_Coordinate: 77
    South_Bounding_Coordinate: 40

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: Mar-2006
    Currentness_Reference: Publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Map

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 10580 x 25545, type Grid Cell

    2. What coordinate system is used to represent geographic features?

      The map projection used is Albers Conical Equal Area.

      Projection parameters:
      Standard_Parallel: 55.00
      Standard_Parallel: 65.00
      Longitude_of_Central_Meridian: -154.00
      Latitude_of_Projection_Origin: 50.00
      False_Easting: 0.0
      False_Northing: 0.0

      Planar coordinates are encoded using Row and column
      Abscissae (x-coordinates) are specified to the nearest 200.0
      Ordinates (y-coordinates) are specified to the nearest 200.0
      Planar coordinates are specified in Meters

      The horizontal datum used is None.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Shaded relief TIFF image grid cell
    Any of the data elements in the shaded relief file. (Source: National Atlas of the United States)

    Shaded relief TIFF image values
    Color values for the TIFF image. (Source: National Atlas of the United States)

    Range of values
    Minimum:0
    Maximum:255


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    John Hutchinson
    SAIC
    USGS Center for EROS
    Sioux Falls, SD 57198-0001
    USA

    605-594-6049 (voice)
    hutch@usgs.gov


Why was the data set created?

The color shaded relief images were developed to portray the terrain of the United States. They are intended for visual purposes only. The original NED data must be used for conducting analysis and determining elevation values.


How was the data set created?

  1. From what previous works were the data drawn?

    National Elevation Dataset (source 1 of 4)
    U.S. Geological Survey, 2002, National Elevation Dataset: U.S. Geological Survey, Sioux Falls, SD.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution: Elevation information.

    shorelp020l (source 2 of 4)
    National Atlas of the United States, 1999, Shoreline file in Lambert Azimuthal Equal Area projection: National Atlas of the United States, Reston, VA.

    Type_of_Source_Media: Internal file
    Source_Contribution: Shoreline mask for area of coverage.

    ElevationAK_2005 (source 3 of 4)
    USGS, Center for EROS, Unpublished material, Alaska Color Elevation Grid, Albers.

    Type_of_Source_Media: Internal file
    Source_Contribution: Elevation information.

    GrayscaleAK_Albers (source 4 of 4)
    USGS, Center for EROS, 200603, Grayscale Alaska Shaded Relief – 200-Meter Resolution, Albers projection: National Atlas of the United States, Reston, VA.

    Online Links:

    Type_of_Source_Media: Online
    Source_Contribution: Elevation information.

  2. How were the data generated, processed, and modified?

    Date: Jan-2005 (process 1 of 2)
    Four elevation mosaics were extracted from the National Elevation Dataset (NED) and used to produce the shaded relief images of the conterminous United States, Alaska, Hawaii, and Puerto Rico and the U.S. Virgin Islands. A separate image was created for each of the four areas because, at 200-meter resolution, file size for an elevation mosaic of all of the United States would exceed the processing capacity of some commonly-used GIS and image processing software packages.
    For Alaska, elevation data were extracted from the NED and projected to an Albers Conical Equal-Area projection, with a pixel size of 200 meters. The datum for NED Alaska data is NAD27, so the data were converted to NAD83 before the projection was performed.
    Using the ArcInfo Polygrid command, a 0/1 land/water mask was created for Alaska at the same 200 meter resolution as the elevation data, using coastline data clipped from the National Atlas shoreline file. The land/water mask was applied to the 16-bit elevation grid. The masked elevation grid as well as the mask itself is available on request. More information on the NED may be found by following the links at <http://ned.usgs.gov>.
    A color elevation image was created by slicing the elevation data using the ranges (listed in feet; divide by 3.2808 to get meters) and RGB color values below.
    From    To     index     red     green   blue
    ---------------------------------------------------
    -250    0      1         220     220     220
    1       249    2         127     159     101
    250     499    3         130     176     112
    500     999    4         160     194     124
    1000    1499   5         185     214     124
    1500    1999   6         207     224     156
    2000    2499   7         223     233     168
    2500    2999   8         241     238     166
    3000    3499   9         237     223     159
    3500    3999   10        240     210     141
    4000    4499   11        230     188     138
    4500    4999   12        216     165     133
    5000    5499   13        197     149     135
    5500    5999   14        217     165     156
    6000    6499   15        227     183     177
    6500    6999   16        223     192     191
    7000    7499   17        239     205     217
    7500    7999   18        244     215     225
    8000    8499   19        243     223     233
    8500    8999   20        248     227     232
    9000    9499   21        248     233     238
    9500    9999   22        246     240     245
    10000   19476  23        255     255     255
    Water          0         132     193     255
    
    

    Data sources used in this process:

    • National Elevation Dataset
    • shorelp020l

    Data sources produced in this process:

    • ElevationAK_2005

    Date: Mar-2006 (process 2 of 2)
    ElevationAK_2005 was converted in Adobe Photoshop from RGB to CMY (no black generated).
    The contrast of GrayscaleAK_Albers was enhanced in Adobe Photoshop by using a tritone technique. The enhanced grayscale image was added as a black band to the converted color elevation image to create a CMYK color shaded relief image. The CMYK image was converted in Photoshop to RGB.
    In the combined image, the water and non-U.S. land areas no longer had the desired values, so they were reset to match those used in the National Atlas Map Maker. Using Adobe Photoshop’s Magic Wand function, ocean water and non-U.S. land were selected and masked. Ocean water was set to RGB value (132, 193, 255) and non-U.S. land was set to RGB value (132, 158, 172).
    The Photoshop image was saved in as a TIFF, ingested into ArcInfo as a grid using the command IMAGEGRID, saved as a TIFF from ArcInfo using the command GRIDIMAGE, and then processed through a USGS GeoTIFF software program to create a fully-compliant GeoTIFF with valid header information.

    Data sources used in this process:

    • ElevationAK_2005
    • GrayscaleAK_Albers

  3. What similar or related data should the user be aware of?

    National Atlas of the United States, 200512, Color Conterminous United States Shaded Relief – 200-Meter Resolution: National Atlas of the United States, Reston, VA.

    Online Links:

    Other_Citation_Details: Lambert Azimuthal Equal Area projection
    National Atlas of the United States, 200512, Color Alaska Shaded Relief – 200-Meter Resolution: National Atlas of the United States, Reston, VA.

    Online Links:

    Other_Citation_Details: Lambert Azimuthal Equal Area projection
    National Atlas of the United States, 200512, Color Hawaii Shaded Relief – 200-Meter Resolution: National Atlas of the United States, Reston, VA.

    Online Links:

    Other_Citation_Details: Lambert Azimuthal Equal Area projection
    National Atlas of the United States, 200512, Color Puerto Rico and the U.S. Virgin Islands Shaded Relief – 200- Meter Resolution: National Atlas of the United States, Reston, VA.

    Online Links:

    Other_Citation_Details: Lambert Azimuthal Equal Area projection
    National Atlas of the United States, 200603, Color Conterminous United States Shaded Relief – 200-Meter Resolution, Albers projection: National Atlas of the United States, Reston, VA.

    Online Links:

    National Atlas of the United States, 200603, Color Hawaii Shaded Relief – 200-Meter Resolution, Albers projection: National Atlas of the United States, Reston, VA.

    Online Links:

    National Atlas of the United States, 200603, Color Puerto Rico and the U.S. Virgin Islands Shaded Relief – 200- Meter Resolution, Albers projection: National Atlas of the United States, Reston, VA.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Data completeness reflects the content of the original NED elevation data.

  5. How consistent are the relationships among the observations, including topology?

    No tests for logical consistency have been performed on this map layer.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None.
Use_Constraints:
None. Acknowledgment of the U.S. Geological Survey, Center for EROS and (or) the National Atlas of the United States would be appreciated in products derived from these data.

  1. Who distributes the data set? (Distributor 1 of 1)

    Earth Science Information Center, U.S. Geological Survey
    507 National Center
    Reston, VA 20192
    USA

    1-888-ASK-USGS (1-888-275-8747) (voice)

    Contact_Instructions:
    In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>.
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. Use of trademarks or formats does not constitute endorsement by the U.S. Geological Survey. There are no copyright restrictions on the use, redistribution, or further processing of this map layer. No responsibility is assumed by the U.S. Geological Survey in the use of these data.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 10-Mar-2006
Metadata author:
Peg Rawson
National Atlas of the United States
12201 Sunrise Valley Drive
Reston, VA 20192
USA

703-648-4183 (voice)
atlasmail@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.12 on Thu Sep 28 14:42:54 2017