Metadata: Identification_Information: Citation: Citation_Information: Originator: Roger Tankersley, Jr. Publication_Date: 1998 Title: nat_dem Edition: 1 Geospatial_Data_Presentation_Form: Map Publication_Information: Publication_Place: Norris TN Publisher: Tennessee Valley Authority Description: Abstract: This map is an ARC/INFO Grid representing the 30 arc second digital elevation model for the United States. Elevation is in meters. Purpose: These data were created as part of a regional assessment of landscape conditions in the mid-Atlantic region (SFR 3) (Jones et al., 1997). Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: Ending_Date: Currentness_Reference: 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: Elevation Theme_Keyword: Slope Theme_Keyword: Theme_Keyword: Theme_Keyword: Theme_Keyword: 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: USGS EROS data center, 30 Arc Second DEM. Native_Data_Set_Environment: These data are presently stored in ARC/INFO format. Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: none Logical_Consistency_Report: none Completeness_Report: Complete Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: None Source_Information: Source_Citation: USGS 30 arc second dem. Citation_Information: Other_Citation_Details: Jones, K.B., Riitters, K.H., Wickham, J.D., Tankersley, R.D., O'Neill, R.V., Chaloud, D.J., Smith, E.R., and Neale, A.C. 1997. An Ecological Assessment of the United States Mid-Atlantic Region: A Landscape Atlas. EPA/600/R97/130, U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. Source_Information: Source_Citation: Citation_Information: Other_Citation_Details: Process_Step: Process_Description: The history of the DEM processing follows: 1. The data set distributed by NGDC is described in this section. The 30-second point topography data set was developed through a series of processing procedures conducted by the Defense Mapping Agency, Topographic Center (DMATC) and the National Telecommunications and Information Administration (NTIA). These procedures are briefly outlined in the following paragraphs. The 30-second database was originally derived from a 3-second digital topographic database called Digital Terrain Data. DMATC developed this 3-second file by digitizing topographic contour lines and geographic features from printing plates that were used to produce the 1:250,000 scale U.S. Geological Survey Topographic maps. The digitized elevation contours were then converted into grids of interpolated elevations, with a single value given for every 3" x 3" coordinate cell. These values corresponded to the elevation given for a point situated in the center of each cell. Elevation data were rounded to the nearest 20 foot interval. DMATC developed the 30-second dataset by simply selecting every 10th data point from the completed Digital Terrain Data file. Selecting every 10th data point from the 3-second gridded Digital Terrain Data file has the effect of reducing the resolution by 100%. Although this may seem undesirable, it has resulted in a very compact, manageable and transportable database of U.S. elevation values. Each elevation in the 30-second file corresponded to the elevation at a point situated in the center of a 30" x 30" coordinate cell. The 30-second data set produced by DMATC contained a significant number of format and data errors. To rectify these problems, NTIA checked, updated and reformatted the data generated by DMATC. This final corrected version of 30-second point topography data is the set currently disseminated by NGDC. Source_Used_Citation_Abbreviation: Source_Produced_Citation_Abbreviation: Process_Date: Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: raster Raster_Object_Information: Raster_Object_Type: 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: VALUE Entity_Type_Definition: Elevation in meters Entity_Type_Definition_Source: ARC/INFO Attribute: Attribute_Label: COUNT Attribute_Definition: Number of cells where in each elevation class. Attribute_Definition_Source: ARC/INFO Attribute_Domain_Values: Range_Domain: Range_Domain_Maximum: Range_Domain_Minimum: Attribute_Measurement_Frequency: None planned Attribute: Attribute_Label: Attribute_Definition: Attribute_Definition_Source: ARC/INFO Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: Range_Domain_Maximum: Attribute_Measurement_Frequency: None planned Overview_Description: Entity_and_Attribute_Overview: 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: 19980901 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Roger Tankersley, Jr. Contact_Organization: University of Tennessee, Department of Geography Contact_Address: Address_Type: Address: 428 G&G Building Address: City: Knoxville State_or_Province: TN Postal_Code: 37996 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