Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Tennessee Valley Authority, Geographic Information and Engineering
      Publication_Date: 19960925
      Title: 7.5 Minute Quadrangle, DRG Format, Alabaster, AL
      Geospatial_Data_Presentation_Form: map
  Description:
    Abstract:
      The Digital Raster Graphic (DRG) is a raster image of a
      scanned USGS topographic map georeferenced to the
      Universal Transverse Mercator grid.
    Purpose:
      A DRG is useful as a source or background layer in a GIS,
      as a means to perform quality assurance on other digital products,
      and as a source for the collection and revision of DLG data.  DRG's
      can also be merged with other digital data, e.g. DEM's or DOQ's, to
      produce a hybrid digital file.
    Supplemental_Information:
      The Universal Transverse Mercator meters
      coordinates of pixel 1,1 are
      x = 510829.84
      y = 3679542.33
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: 1980
    Currentness_Reference: Ground Condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: Irregular
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -86.875
      East_Bounding_Coordinate: -86.750
      North_Bounding_Coordinate: 33.250
      South_Bounding_Coordinate: 33.125
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: digital raster graphic
      Theme_Keyword: DRG
      Theme_Keyword: topographic map
    Place:
      Place_Keyword_Thesaurus:
        Department of Commerce, 1977, Countries,
        Dependencies, Areas of Special Sovereignty, and their Principal
        Administrative Divisions. (Federal Information Processing
        Standard 10-3): Washington, Department of Commerce, National
        Institute of Standards and Technology.
      Place_Keyword: US
      Place_Keyword_Thesaurus:
        Department of Commerce, 1987, Codes for
        the Identification of the STATES, The District of Columbia and the
        Outlying Areas Of The United States, and Associated Areas.
        (Federal Information Processing Standard 5-2): Washington,
        Department of Commerce, National Institute of Standards and
        Technology.
      Place_Keyword:
        AL



  Access_Constraints: None
  Use_Constraints:
    Acknowledgement of the U.S. Tennessee Valley Authority, Geographic
    Partnerships Program would be appreciated in products derived
    from these data.
  Data_Set_Credit:
    This DRG was produced through the Tennessee Valley
    Authority, Geographic Partnerships program.  External partners on
    the project included the Tennessee Department of Transportation and
    the Natural Resources Conservation Service (Tennessee).
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Tennessee Valley Authority, Geographic Information and Engineering

      Contact_Address:
        Address_Type: mailing address
        Address: HB 2A-C, 1101 Market St.
        City: Chattanooga
        State_or_Province: TN
        Postal_Code: 37402-2801
      Contact_Voice_Telephone: 1 423 751 8640
      Contact_TDD/TTY_Telephone: 1 423 751 8500
      Contact_Facsimile_Telephone: 1 423 751 8525
      Contact_Electronic_Mail_Address:
        mapstore@tva.gov




Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      The DRG is an 8-bit color image which employs a color palette
      to ensure uniform colors throughout a particular DRG series.
      That is to say, if a color is defined as having a particular
      RGB value, for all DRG's within that series, the RGB value is
      the same.
  Logical_Consistency_Report: Not Applicable
  Completeness_Report:
    The Digital Raster Graphic (DRG) is a faithfully reproduced
    digital image of the original source map.  Some differences
    may be detected between the source graphic used and the DRG
    due to the RGB values assigned that particular color.  The
    intent is to recreate those colors as near as possible.  Data
    completeness for digital raster graphic files reflect content
    of the source graphic.  Features may have been eliminated or
    generalized on the source graphic, due to scale and legibility
    constraints.  For information on collection and inclusion
    criteria, see U.S. Geological Survey, 1994, Standards for
    1:24,000-Scale Digital Line Graphs and Quadrangle Maps:
    National Mapping Program Technical Instructions and U.S. Geological
    Survey, 1994, Standards for Digital Line Graphs:  National
    Mapping Program Technical Instructions.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report:
        The horizontal position accuracy is that of the original map.
        The map scanning process introduces an insignificant amount of
        distortion.  The coordinate system of the DRG is Universal Transverse Mercator
        and may be different from that of the original map (as shown
        on the map image collar).
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report:
        Refer to the DRG collar or the collar of the published map for
        information about vertical positional accuracy.
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: USGS
          Publication_Date: 1980
          Title: Alabaster, AL
          Geospatial_Data_Presentation_Form: map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher: USGS
      Source_Scale_Denominator: 24000
      Type_of_Source_Media: paper
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 1980
        Source_Currentness_Reference: ground condition
      Source_Citation_Abbreviation: map1
      Source_Contribution: The source map which was scanned to produce the digital raster graphic.
    Process_Step:
      Process_Description:
        The production procedures, instrumentation, hardware and software
        used in the collection of standard U.S. Geological Survey (USGS)
        Digital Raster Graphic (DRG) products vary depending on systems
        used at the contract, cooperator or National Mapping Division (NMD)
        production sites.  The majority of DRG datasets are acquired through
        government contract. The process step describes, in general, the
        process used in the production of standard USGS DRG datasets.

        1. Production of a DRG begins with the scanning of a paper
        7.5-minute topographic map (map1) on a high resolution scanner.
        The map is scanned at 500 dpi and produces an output file of
        between 15-75 mb in size.

        2. Color classification to reduce the number of colors and assigning
        the standard DRG colors takes place during the scanning phase.

        3. The image is then descreened (removal of map printing screens) to
        reduce file size.

        4. The raw scan file is then transformed and georeferenced using
        plane coordinates of the 16 2.5-minute grid ticks which are obtained
        using the Intergraph Projection Manager program and stored in a
        ground control file. Those 16, 2.5-minute ticks are interactively
        visited and assigned their respective grid coordinate.  Intergraph
        IRASC program then performs an affine coordinate transformation warp.
        The image is subsampled to 250 dots per inch (dpi) to produce
        resolution of 2.4 meters (8.0 feet) in the warp process.

        5.  The image file is converted to a Tagged Image File Format
        (TIFF), and further reduced by converting the file to a run length
        encoding PackBit compression (type 32773).

        6.  Prior to archival the DRG undergoes the following quality
        assurance procedures;

        a. All DRG files are inspected to ensure that they are
        geometrically consistent with normal map presentation.

        b. Selected DRG's are checked to ensure that data elements in
        the DRG metadata file correspond to the map collar information
        and to the information in the associated image file.

        c. Selected DRG's are checked for georeferencing accuracy by
        comparing the book value of latitude and longitude tick marks
        to corresponding tick intersections in the DRG image.

        d. Transformations are checked on selected DRG's by comparing
        the positions of well defined points such as plane grid
        intersections in the graphic product to the corresponding image
        points in the DRG.

      Source_Used_Citation_Abbreviation: map1
      Process_Date: 19960925

Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Pixel
    Row_Count: 6898
    Column_Count: 5542

Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Grid_Coordinate_System:
        Grid_Coordinate_System_Name: Universal Transverse Mercator
        Universal_Transverse_Mercator:
          UTM_Zone_Number: 16
          Transverse_Mercator:
            Longitude_of_Central_Meridian: -87.000
            Latitude_of_Projection_Origin: 0.0
            False_Easting: 500000.0
            False_Northing: 0.0
            Scale_Factor_at_Central_Meridian: 0.9996
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 2.4
          Ordinate_Resolution: 2.4
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1927
      Ellipsoid_Name: Clark 1866
      Semi-major_Axis: 6378206.40
      Denominator_of_Flattening_Ratio:
        294.98


Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview:
      Each raster entity or pixel contains a color index from 0 through
      12 referencing a color palette of RGB values from O through 255 in
      which the standard colors used in the DRG are defined.
      Index   Color          Red      Green    Blue

      0       Black          0        0        0
      1       White          255      255      255
      2       Blue           0        151      164
      3       Red            203      0        23
      4       Brown          131      66       37
      5       Green          201      234      157
      6       Purple         137      51       128
      7       Yellow         255      234      0
      8       Light Blue     167      226      226
      9       Light Red      255      184      184
      10      Light Purple   218      179      214
      11      Light Grey     209      209      209
      12      Light Brown    207      164      142
    Entity_and_Attribute_Detail_Citation: Draft Standards for Digital Raster Graphic.

Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Tennessee Valley Authority, Geographic Information and Engineering, Map Information and Records Team.
      Contact_Address:
        Address_Type: mailing address
        Address: HB 2A-C, 1101 Market St.
        City: Chattanooga
        State_or_Province: TN
        Postal_Code: 37402-2801
      Contact_Voice_Telephone: 1 800 MAPSTVA
      Contact_TDD/TTY_Telephone: 1 423 751 8500
      Contact_Facsimile_Telephone: 1 423 751 8525
      Contact_Electronic_Mail_Address:
        mapstore@tva.gov



  Distribution_Liability:
    Although these data have been processed successfully on a computer
    system at the U.S. Tennessee Valley Authority (TVA), no warranty expressed
    or implied is made by the TVA regarding the utility of the data on any
    other system, nor shall the act of distribution constitute any such
    warranty. The TVA will warrant the delivery of this product in
    computer-readable format, and will offer appropriate adjustment of
    credit when the product is determined unreadable by correctly adjusted
    computer input peripherals, or when the physical medium is delivered
    in damaged condition.  Requests for adjustment of credit must be made
    within 30 days from the date of this shipment from the ordering site.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: TIFF
        Format_Version_Number: 5.0
        File_Decompression_Technique: PackBit
      Digital_Transfer_Option:
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format: ISO 9660;  DRG image files with corresponding metadata files.
    Fees: Contact TVA Map Store at 1-800-MAPSTVA for current price.

Metadata_Reference_Information:
  Metadata_Date: 19960925
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Tennessee Valley Authority, Geographic Information and Engineering.
      Contact_Address:
        Address_Type: mailing address
        Address: HB 2A-C, 1101 Market St.
        City: Chattanooga
        State_or_Province: TN
        Postal_Code: 37402-2801
      Contact_Voice_Telephone: 1 423 751 8640
      Contact_TDD/TTY_Telephone: 1 423 751 8500
      Contact_Facsimile_Telephone: 1 423 751 8525
      Contact_Electronic_Mail_Address:
        mapstore@tva.gov



  Metadata_Standard_Name: Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: 19940608
