Metadata:
  Identification_Information:
    Citation:
      Citation_Information:
        Originator: Kurt Riitters, Southern Appalachian Field Laboratory, 
                    Biological Resources Division, U.S. Geological Survey
        Publication_Date: 1998
        Title: UINDEX27-9
        Edition: 1
        Geospatial_Data_Presentation_Form: Map
        Publication_Information:
          Publication_Place: Norris, TN
          Publisher: Tennessee Valley Authority
        
    Description:
      Abstract:
         This dataset is a grid map that portrays an index of human use, defined as
         the proportion (area percent) of a defined landscape which has agriculture
         or urban land cover types  (U-Index,
         O'Neill et al. 1988).  The U-Index was calculated at 65.61 ha scale (that is, within
          65.61 hectare analysis windows) for the United States
         Standard Federal Region III (SFR 3)  at 30 meter resolution, and stored at 7.29 hectare
          resolution following median-filtering in 7.29 ha analysis windows. The dataset was created 
          by applying 
         spatial filters to a published map of  land cover known as " U.S. Federal 
         Region III Land Cover Data Set", which was obtained  from the Multi-
         Resolution Land Characteristics (MRLC) Consortium.  The spatial filter 
        computed the U-Index within 65.61 ha (27x27 pixel) 
        windows from the proportions of land cover types within a window.
        The [0,1] continuous index was discretized,
        and a byte representation [1,255] of the index value was stored at the center
        location in each window.  The resulting surface map was then median-filtered by
        a spatial filter in 7.29 ha (9 x 9 pixel) analysis windows.

      Purpose:
        These data were originally created as part of a regional assessment of landscape conditions
         in the mid-Atlantic region (SFR 3), based on digital land cover maps 
        derived from remote sensing (TM) and produced by the Multi-Resolution
        Land Characteristics Consortium.  The U-Index map portrays
        relative degrees of human use, considering only the relative area of agriculture
        plus developed land cover
        types, and for a single spatial scale.  This map was prepared for contextual information
        and to portray regional conditions, other approaches were used to calculate the Uindex
        separately for watersheds in SFR 3 for assessment purposes.

    Time_Period_of_Content:
      Time_Period_Information:
        Range_of_Dates/Times:
          Beginning_Date: 1991
          Ending_Date: 1993
      Currentness_Reference: Dates of satellite imagery.

    Status:
      Progress: Complete
      Maintenance_and_Update_Frequency: None planned

   Spatial_Domain:
      Bounding_Coordinates:
        West_Bounding_Coordinate: -84 degrees West
        East_Bounding_Coordinate: -74 degrees West
        North_Bounding_Coordinate: 43 degrees North
        South_Bounding_Coordinate: 36 degrees North
      
    Keywords:
      Theme:
        Theme_Keyword_Thesaurus: None
        Theme_Keyword: pattern
        Theme_Keyword: landcover
        Theme_Keyword: United States
        Theme_Keyword: agriculture
        Theme_Keyword: urban
      Place:
        Place_Keyword_Thesaurus: None
        Place_Keyword: United States
        Place_Keyword: Standard Federal Region III

    Access_Constraints: None

    Use_Constraints: None

    Point_of_Contact:
      Contact_Information:
        Contact_Person_Primary: Bruce Jones
          Contact_Person: 
          Contact_Organization: EPA Landscape Ecology Division
        Contact_Address:
          Address_Type: mailing and physical address
          Address: U.S. Environmental Protection Agency, Box 93478
          City: Las Vegas
          State_or_Province: Nevada
          Postal_Code: 89193-3478
        Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov

    Data_Set_Credit: The basic data from which this map was derived were provided by the 
         Multi-Resolution Land Characteristics Consortium

    Native_Data_Set_Environment:

      These data are presently stored in ARC/INFO GRID format.

  Data_Quality_Information:
     Attribute_Accuracy:
        Attribute_Accuracy_Report:
         The U-Index is an area density index; the measured variable is the proportion of pixels in 
         an analysis window which have a
         given land cover type(s) (see Process_Step sections; Riitters et al. 1996).  A statistical 
         rule of thumb is that 50 observations are needed in order to 
         accurately estimate a proportion.  The analysis window was 27x27 pixels in size, which 
         corresponds to a potential maximum of 729 pixels (less missing values, if any). This index is  one of several which could have been used to quantify 'area density', for a discussion of 
         relative strengths and weaknesses please consult a standard textbook on landscape 
         ecology or image processing.  Like other indices, this index is best interpreted as a relative 
         value, in comparison to other pixels on the same map.  Comparisons with other maps 
         prepared from different data sources or at different scale are tenuous.

     Logical_Consistency_Report:
      All cell values are in the range [1,255].   Missing values were assigned to  
      cells which were labeled as water on the MRLC land cover map, or which occur outside the 
      boundary of the assessment region.
            
    Completeness_Report:
     Every cell in the original land cover map has a non-zero byte value representing the 
     U-Index, unless the cell was labeled as water in the land cover map.  In the latter
     instance, the cell was assigned a 'missing' data value.

    Positional_Accuracy:
      Horizontal_Positional_Accuracy:
        Horizontal_Positional_Accuracy_Report:
	The positional accuracy of the U-Index map is the same as the
             positional accuracy of the land cover map from which the U-Index map was
             derived.
       
    Lineage:
      Source_Information:
          Source_Citation:
          Citation_Information:
            Originator: 
            Publication_Date: 1996
            Title: U.S. Federal Region III Land Cover Data Set
Edition: 
Geospatial_Data_Presentation_Form: remote-sensing image 
Series_Information: 
            Series_Name: U.S. Federal Region III 
            Publication_Information:
              Publication_Place: Sioux Falls, SD, USA
              Publisher:  
        Type_of_Source_Media: online
        Source_Time_Period_of_Content:
          Time_Period_Information:
            Range_of_Dates/Times:
              Beginning_Date: 1991
              Ending_Date: 1993
          Source_Currentness_Reference: Dates of satellite imagery.
          Source_Citation_Abbreviation: MRLC-R3V1 
          Source_Contribution: Land cover map 
      Source_Information:
          Source_Citation:
            Citation_Information:
             Other_Citation_Details: Riitters, K.H., O'Neill, R.V., and Jones, K. B.  1997.  Assessing
               habitat suitability at multiple scales: a landscape-level approach.  Biological 
              Conservation 81:191-202.
Source_Information:
          Source_Citation:
            Citation_Information:
             Other_Citation_Details: O'Neill, R.V.,  with 11 others.  1988.  Indices of landscape pattern.
                  Landscape Ecology 1:153-162.

Process_Step:
        Process_Description:  Derivation of U-Index from land cover.

           Land cover data (MRLC-R3V1) obtained from EROS Data Center in Arc Grid
           format.  Individual pixels were re-classified into "U" and "Not U"  classes
           by using the following scheme:
	Original MRLC class                                               U-class
             ----------------------------				-------------------------------
                1 - water 					Missing
	          2 - low intensity developed 			U
                3 - high intensity developed			U
  		    4 - hay/pasture/grass				U
                5 - row crops					U
                6 - probable row crops			U
                7 - conifer forest				Not U
                8 - mixed forest				Not U
                9 - deciduous forest				Not U 
              10 - woody wetland				Not U 
              11 - emergent wetland				Not U
              12 - bare; quarries				U
              13 - bare; coal mines				U
              14 - bare; beach				Not U
	        15 - bare; transitional				U
           Land cover data exported to ascii format using the ARC/INFO command
           GRIDASCII, and format converted to an in-house format using an in-house
           software tool named ASC2TVA.C.

          The map was then subdivided into sixteen (16) overlapping rectangles for further
          processing using an in-house software tool named SPLITTER.C.  The
          rectangles overlapped in order to avoid artifacts near image boundaries
          during the spatial filtering operations.

Each of the 16 sub-rectangles were then processed via spatial filtering to
          estimate the U-Index as described below.  The spatial filtering
          program is an in-house software tool named SPATCONV.C.
Each of the 16 sub-rectangles were then processed via spatial filtering to
          find the median U-Index in 9x9 pixel windows.  The spatial filtering
          program is an in-house software tool named SPATCONV.C.  Results of
          this step were stored at 270-meter (7.29 ha) resolution.

          After spatial filtering, the map of area density index values was reconstructed
          by reversing the steps, including reassembling the 16 sub-rectangles into a
          single image (via an in-house software tool named LUMPER.C, which removed
           the overlapping parts of rectangles), converting the format to ascii (using the
          in-house software tool named TVA2ASC.C), and finally bringing it back into
          ARC/INFO using their command ASCIIGRID.

          Note:  The georeferencing did not change as a result of reformatting,
          exporting/importing, or the first spatial filtering step.  The second spatial filter
          (median-filtering) introduced a probable georeferencing error of not more than
          270 meters which was deemed acceptable since the purpose of this map was
          to portray regional trends in a graphic format; other procedures were used to
          calculate the U-Index separately for each watershed for assessment purposes.

Spatial filtering proceeded as follows.  A 65.61 ha (27x27 pixels) quadrat was
          centered on each pixel of the original land cover map.  The numbers of "U" and "not U"
          pixels were then tabulated for the non-missing pixels in the window. The 
          area density index was then computed as the frequency of  "U" pixels, divided by
          the total frequency of non-missing pixels.
          Note that this expression yields a value of 0 when no "U" pixels are present, and
          and a value of 1 when all pixels in a window are "U".
 The calculated values were discretized to
          the range [1,255] and stored at 30-meter spatial resolution.  Thus, a pixel
          value in the new map represents the U-Index of the surrounding
          65.61 ha in the original land cover map.  Pixels representing water were not
          included in the area density calculations, and  no calculation was made if the
          quadrat was centered on a water pixel (and a 'missing' value was assigned 
          to the center pixel).
The 30-meter U-Index map was then median-filtered using 9x9 pixel windows and the 
          results of this step were stored at 7.29 ha resolution (270 m).  A pixel value in 
          this map, then, represents the median value of the U-Index for the 81 30-m 
          pixels in an analysis window before filtering.

          The transformation used to discretize the index values was:
                  D = ( C * 254) + 1
                  where
                  D = discretized value in range [1,255]
                  C = calculated value of area density index in range [0,1]

           If needed, the original calculated values can be approximated by applying
           the backtransformation:
                   C = (D - 1) / 254

          Note that the backtransformed values will be in steps of size approximately
          0.00394 as a result of the discretization process (precision has been lost).

      Source_Used_Citation_Abbreviation: MRLC-R3V1
      Source_Produced_Citation_Abbreviation: 
      Process_Date: 1996

   Spatial_Data_Organization_Information:
    Direct_Spatial_Reference_Method: Raster

    Raster_Object_Information:
        Raster_Object_Type: Grid Cell
        Row_Count: 
        Column_Count: 

Spatial_Reference_Information:
    Horizontal_Coordinate_System_Definition: Planar:
        Map_Projection:
          Map_Projection_Name: Lambert_Azimuthal
             Lambert_Azimuthal:
            Radius of Sphere of Reference: 6370997
            Longitude_of_Central_Meridian: -100 0 0
            Latitude_of_Projection_Origin: 45 0 0
            False_Easting: 0.0
            False_Northing: 0.0
        Planar_Coordinate_Information:
          Planar_Coordinate_Encoding_Method: Row and column
          Coordinate_Representation:
            Abscissa_Resolution: 
            Ordinate_Resolution: 
          Planar_Distance_Units: meters

  Entity_and_Attribute_Information:
    Detailed_Description:
      Entity_Type:
        Entity_Type_Label: Uindex27-9.VAT
        Entity_Type_Definition: Value attribute table of Uindex27-9 grid cells
        Entity_Type_Definition_Source: ARC/INFO
      Attribute:
        Attribute_Label: VALUE
        Attribute_Definition: Byte value representation of U-Index.
        Attribute_Definition_Source: software computed
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Maximum: 255 (integer)
            Range_Domain_Minimum: 0 (integer)
        Attribute_Measurement_Frequency: None planned
      Attribute:
        Attribute_Label: COUNT
        Attribute_Definition: Number of grid cells with indicated VALUE
        Attribute_Definition_Source: software computed
        Attribute_Domain_Values:
          Range_Domain:
            Range_Domain_Minimum: positive integer
            Range_Domain_Maximum: positive integer
        Attribute_Measurement_Frequency: None planned

    Overview_Description:
      Entity_and_Attribute_Overview:
        The value attribute table associated with this raster:
   
    DATAFILE NAME: Uindex27-9.VAT
        2 ITEMS: STARTING IN POSITION    1
        COL  ITEM NAME         WIDTH    OUTPUT TYPE   N.DEC  ALTERNATE NAME  INDEXED
        01     VALUE                     4             10            B             -                    -                      Indexed
        05     COUNT                    4             10            B             -                    -                           -
     

      Entity_and_Attribute_Detail_Citation: Not available

  Distribution_Information:
    Distributor:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Bruce Jones
          Contact_Organization: EPA Landscape Ecology Division
        Contact_Address:
          Address_Type: 
          Address: U.S. Environmental Protection Agency, Box 93478
          City: Las Vegas
          State_or_Province: Nevada
          Postal_Code: 89193-3478
         Contact_Electronic_Mail_Address: jones.bruce@epamail.epa.gov

  Metadata_Reference_Information:
    Metadata_Date: 19980902
    Metadata_Contact:
      Contact_Information:
        Contact_Person_Primary:
          Contact_Person: Kurt Riitters
          Contact_Organization: U.S. Geological Survey- Biological Resources Division
        Contact_Address:
          Address_Type: mailing and physical address
          Address: NCSU Forestry Dept.
          Address: 3024-C Biltmore Hall
          City: Raleigh
          State_or_Province: NC
          Postal_Code: 27695
    Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
    Metadata_Standard_Version: 19940608
    Metadata_Security_Information:
      Metadata_Security_Classification_System: None
      Metadata_Security_Classification: Unclassified
      Metadata_Security_Handling_Description: None