Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Geological Survey
      Publication_Date: 1996
      Title: Thompson Quadrangle DRG
      Publication_Information:
        Publication_Place: Reston, Virginia
        Publisher: U.S. Geological Survey

      Other_Citation_Details: none
      Online_Linkage: ftp://www.pasda.psu.edu/pub/pasda/drg24k/thompson_pa.zip
      Larger_Work_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: Unknown
          Title: Digital Raster Graphic
          Publication_Information:
            Publication_Place: Reston, Virginia
            Publisher: U.S. Geological Survey

          Other_Citation_Details: none
          Online_Linkage:
            http://www.usgs.gov





  Description:
    Abstract:
      A Digital Raster Graphic (DRG) is a raster image of a scanned USGS
      topographic or planimetric map including the collar information, georeferenced to
      the UTM 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 vector data.  DRGs can also be merged with other digital
      data, for example, DEMs or DOQs to produce a hybrid digital file.

  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date:
          Unknown


    Currentness_Reference: ground condition

  Status:
    Progress: complete
    Maintenance_and_Update_Frequency: irregular

  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -75.625
      East_Bounding_Coordinate: -75.5
      North_Bounding_Coordinate: 41.875
      South_Bounding_Coordinate:
        41.75


  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: none
      Theme_Keyword: digital raster graphic
      Theme_Keyword: drg
      Theme_Keyword: topographic quadrangle
      Theme_Keyword: topographic map
      Theme_Keyword: raster image

    Place:
      Place_Keyword_Thesaurus: none
      Place_Keyword: Pennsylvania
      Place_Keyword:
        Thompson Quadrangle


  Access_Constraints: none

  Use_Constraints:
    Acknowledgment of the USGS would be appreciated in products derived
    from these data.
  Point_of_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey

      Contact_Address:
        Address_Type: mailing address
        Address: 508 National Center
        City: Reston
        State_or_Province: VA
        Postal_Code: 22092

      Contact_Voice_Telephone:
        1-800-USA-MAPS




Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
      The DRG uses a standard palette to ensure uniform color throughout a particular map series. The RGB values for a particular color, therefore, will remain consistent throughout that DRG series. Although the color values of the DRG may sometimes match those of the paper source map, a user will usually notice small differences between the colors on the digital image and on the paper map. Also, the quality of the user's monitor affects the DRG color displayed. Although the DRG generally contains the complete content of the source map, features may occasionally be blurred because of substandard source materials. The DRG also may contain misclassified pixels (color noise).
      The DRG is an 8-bit color image that employs a color palette to ensure uniform colors throughout a particular DRG series. All DRG's within a series must have the same RGB value.

  Logical_Consistency_Report: The USGS DRG is produced with the intention of replicating as close as possible the original source map. Users of the DRG will note, however, that a certain amount of "noise" can be discerned when small areas are blown up or viewed under zoomed-in conditions. This noise is in the form of random specks or pixels of color and halos due to any number of factors, such as, the quality of the source, the use of screens and patterns on the litho, and the unevenness of ink due to saturation and absorption. Discontinuities or breaks in linear features may also be present and are due to improper calibration or usage of the scanner, the condition of the source, and resampling.  Descreening, quantizing, and noise filtering are methods used to reduce noise, which, besides creating a more aesthetically pleasing image, have the added benefit of reducing the size of the image file. Removal of lithographic screen patterns is preferred but not required.
  Completeness_Report: Image completeness is checked by visually inspecting a sampling of DRG's. Each selected DRG will be examined for gaps (missing data) in the main body of the map, the map collar, the overedge areas, and any insets
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
    Vertical_Positional_Accuracy:
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: U.S. Geological Survey
          Publication_Date: Unknown
          Title: 7.5 Minute Series Topographic Quadrangles
          Geospatial_Data_Presentation_Form: map
          Publication_Information:
            Publication_Place: Reston, VA
            Publisher:
              U.S. Geological Survey



      Source_Scale_Denominator: 24,000
      Type_of_Source_Media: paper
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date:
              Unknown


        Source_Currentness_Reference: ground condition

      Source_Citation_Abbreviation: map1
      Source_Contribution: The source map is scanned to produce the DRG

    Process_Step:
      Process_Description:
        The production procedures, instrumentation, harware and software used in the
        collection of standard DRG products vary depending on systems used at the
        contract, cooperator, or the USGS production sites.  The majority of DRG data sets
        are acquired through government partnership and contract.  The process step
        describes, in general, the process used in the production of DRGs from
        1:24,000-scale maps.
        1. Production of a DRG begins with the scanning of a paper
        7.5-minute topographic map (map1) on a high-resolution scanner. Scanning
        resolutions range from 500-1,000 dpi with an output file of 160-300 Mb in size.
        2. Removal of screens (descreening) and color quantization to reduce  the number
        of colors also takes place during the scanning phase.
        3. The raw scan file is then transformed and georeferenced using UTM coordinates
        of the sixteen 2.5-minute grid ticks, which are obtained using the in-house
        produced program COORDAT and stored in a ground control file.  Those sixteen
        2.5-minute ticks are interactively visited and assigned their respective UTM
        coordinates. The USGS program XSHAPES4 then performs a piecewise linear rubber
        sheet transformation.
        4. An output resolution of 2.4 meters (8.2 feet) is chosen to resample the file to
        250 dpi.
        5.  The image file is converted to a TIFF 6.0 image and further reduced by
        converting the file to a run length encoded PackBits compression (type 32773).
        6.  The color palette of the compressed DRG is then standardized by replacing the
        original RGB values assigned during the scanning process with standard RGB value
        combinations using the in-houseproduced TIFFREMAP program.
        7. The DRG metadata file is completed.
        8.  Prior to archiving the DRG undergoes the following quality  assurance
        procedures:
        a. The color index values of each DRG are checked to ensure
        the RGB combinations are consistent with the standardized
        color palette.
        b. All DRG files are inspected to ensure that they are
        geometrically consistent with normal map presentation.
        c. 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.
        d. Selected DRG's are checked for georeferencing accuracy by
        comparing the General Cartographic Transformation Package
        (GCTP) calculated value of latitude and longitude tick marks
        with corresponding tick intersections in the DRG image.
        e. Transformations are checked on selected DRG's by comparing
        the positions of well defined points, such as UTM grid
        intersections in the graphic product, with the corresponding
        image points in the DRG.

      Process_Date:
        1997




Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type:
      Pixel


Spatial_Reference_Information:
  Horizontal_Coordinate_System_Definition:
    Planar:
      Grid_Coordinate_System:
        Grid_Coordinate_System_Name: Universal Transverse Mercator
        Universal_Transverse_Mercator:
          UTM_Zone_Number:
            18


      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 25.40000078
          Ordinate_Resolution: 25.40000078

        Planar_Distance_Units:
          meters


    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1927
      Ellipsoid_Name: Clarke 1866
      Semi-major_Axis: 6378206.4
      Denominator_of_Flattening_Ratio:
        294.98




Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview: Each raster entity or pixel contains a digital number from 0 through 12 referencing a color palette of RGB values from 0 through 255 in which the standard colors used in the DRG are defined.
    Entity_and_Attribute_Detail_Citation:
      Standards for Digital Raster Graphic



Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: Pennsylvania Spatial Data Access (PASDA)

      Contact_Address:
        Address_Type: mailing and physical address
        Address: Land and Water Building
        City: University Park
        State_or_Province: PA
        Postal_Code: 16802
        Country: USA

      Contact_Instructions: Contact via email
      Contact_Electronic_Mail_Address:
        pasda@psu.edu


  Distribution_Liability: The USER shall indemnify, save harmless, and, if requested, defend those parties involved with the development and distribution of this data, their officers, agents, and employees from and against any suits, claims, or actions for injury, death, or property damage arising out of the use of or any defect in the FILES or any accompanying documentation. Those parties involved with the development and distribution excluded any and all implied warranties, including warranties or merchantability and fitness for a particular purpose and makes no warranty or representation, either express or implied, with respect to the FILES or accompanying documentation, including its quality, performance, merchantability, or fitness for a particular purpose. The FILES and documentation are provided "as is" and the USER assumes the entire risk as to its quality and performance. Those parties involved with the development and distribution of this data will not be liable for any direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the FILES or any accompanying documentation.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: Tagged Image File Format (TIFF)
        Format_Version_Number: 6.0
        File_Decompression_Technique: zip

      Digital_Transfer_Option:
        Online_Option:
          Computer_Contact_Information:
            Network_Address:
              Network_Resource_Name:
                http://www.pasda.psu.edu







Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey EROS Data Center

      Contact_Position: Customer Services Representative
      Contact_Address:
        Address_Type: mailing and physical address
        Address: Customer Services U.S. Geological Survey EROS Data Center
        City: Sioux Falls
        State_or_Province: SD
        Postal_Code: 57198
        Country: USA

      Contact_Voice_Telephone: 605-594-6151
      Contact_TDD/TTY_Telephone: 605-594-6933
      Contact_Facsimile_Telephone: 605-594-6589
      Contact_Electronic_Mail_Address: custserv@edcmail.cr.usgs.gov
      Hours_of_Service: 7:30 am to 4:00 pm CT
      Contact_Instructions:
        Automated Ordering. Your order is forwarded to Customer Services at the U.S. Geological Survey's EROS Data Center. A Customer Services Representative contacts you to discuss your order and your mode of payment.

        Manual Ordering. Write down the ordering ID(s) for your item(s). Contact Customer Services.

  Distribution_Liability:
    Although these data have been processed successfully on a computer system at the USGS, no warrenty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty.  The USGS 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 90 days of the shipment from the
    ordering site.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: TIFF
        Format_Version_Number: 6.0
        Format_Version_Date: Unknown

      Digital_Transfer_Option:
        Offline_Option:
          Offline_Media: CD-ROM
          Recording_Format:
            ISO 9660



    Fees:
      From USGS: $32 for each cd-rom.  FTP from http://www.pasda.psu.edu free
      of charge

Metadata_Reference_Information:
  Metadata_Date: 19961125
  Metadata_Review_Date: 19990726
  Metadata_Contact:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: PASDA

      Contact_Electronic_Mail_Address:
        pasda@psu.edu


  Metadata_Standard_Name: Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998

