Identification_Information: Citation: Citation_Information: Originator: Greg Desmond Publication_Date: 200710 Title: High Accuracy Elevation Data - truck Geospatial_Data_Presentation_Form: text files, shapefiles Online_Linkage: http://sofia.usgs.gov/exchange/desmond/desmondelev.html Description: Abstract: The High Accuracy Elevation Data Project collected elevation data (meters) on a 400 meter topographic grid with a vertical accuracy of +/- 15 centimeters to define the topography in South Florida. The data are referenced to the horizontal datum North American Datum 1983 (NAD 83) and the vertical datum North American Vertical Datum 1988 (NAVD 88). The High Accuracy Elevation Data Project began with a pilot study in FY 1995 to determine if the then state-of-the-art GPS technology could be used to perform a topographic survey that would meet the vertical accuracy requirements of the hydrologic modeling community. The initial testing platform was from a truck and met the accuracy requirements. Data were collected in areas near Homestead, Florida. The data are available for the areas shown on the USGS High Accuracy Elevation Data graphic at http://sofia.usgs.gov/exchange/desmond/desmondelev.html. Purpose: These data are from topographic surveys to collect and provide elevation data to parameterize hydrologic and ecological numerical simulation models that were being developed for ecosystem restoration activities. Surveying services were also rendered to provide vertical reference points for numerous water level gauges. Modeling of sheet flow and water surface levels in the wetlands of South Florida is very sensitive to changes in elevation due to the expansive and extremely low relief terrain. Hydrologists have determined minimum vertical accuracy requirements for the elevation data for use as input to hydrologic models. As a result, elevation data with a vertical accuracy specification of +/-15 centimeters (cm) relative to the North American Vertical Datum of 1988 (NAVD88) were collected in critical areas using state-of-the-art differential global positioning system (GPS) technology and data processing techniques. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1995 Ending_Date: 1996 Currentness_Reference: ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: As needed Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -80.625 East_Bounding_Coordinate: -80.25 North_Bounding_Coordinate: 25.625 South_Bounding_Coordinate: 25.375 Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: High accuracy elevation data Theme_Keyword: mapping Theme_Keyword: digital elevation data Theme_Keyword: DEM Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: elevation Theme_Keyword: 006 Place: Place_Keyword_Thesaurus: Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, National Institute of Standards and Technology Place_Keyword: United States Place_Keyword: US Place: Place_Keyword_Thesaurus: U.S. 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, DC, NIST Place_Keyword: Florida Place_Keyword: FL Place: Place_Keyword_Thesaurus: Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology Place_Keyword: Miami-Dade County Place: Place_Keyword_Thesaurus: USGS Geographic Names Information System Place_Keyword: Goulds Place_Keyword: Perrine Place_Keyword: Grossman Hammock Place_Keyword: Royal Palm Ranger Station Place: Place_Keyword_Thesaurus: none Place_Keyword: South East Coast Access_Constraints: none Use_Constraints: None. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data. Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Bob Glover Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 521 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Voice_Telephone: 703 648-5056 Contact_Electronic_Mail_Address: rglover@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: http://sofia.usgs.gov/exchange/desmond/desmondelev.html Browse_Graphic_File_Description: USGS High Accuracy Elevation Data Browse_Graphic_File_Type: GIF Browse_Graphic: Browse_Graphic_File_Name: http://sofia.usgs.gov/exchange/desmond/atlas/ Browse_Graphic_File_Description: USGS HAED Electronic Atlas (view data by USGS 24K topographic quads) Browse_Graphic_File_Type: GIF Data_Set_Credit: Data collection done by Charles Henkle, Gordon Shupe, Bob Glover, Ed Cyran, and Greg Desmond of the USGS and contractors. Other project personnel include Vince Caruso, Gary Freeman, and Susan Price. Native_Data_Set_Environment: compressed ESRI shapefile (.zip) and comma-separated value file (.csv) Data_Quality_Information: Logical_Consistency_Report: Grossman Hammock and Royal Palm Ranger Station are included in both the helicopter AHF & airboat and truck datasets Completeness_Report: All verified and accepted data points are included in the files for each area Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal positions are established by GPS observations and are referenced to the North American Datum of 1983 (NAD83). The desired horizontal accuracy is +/- 15 centimeters. This level of accuracy is consistent with GPS differential techniques which use two stations - a high-quality dual-frequency GPS receiver base station and a roving GPS station. The density and accuracy of a given GPS data observation varies from a few meters to a few centimeters according to the Position Dilution of Precision (PDOP) in the study area. Generally if the PDOP is observed to be excessive, data collection is discontinued or the data are discarded. The PDOP is an indicator of the positional accuracy of the GPS that be can derived from the current GPS satellite geometry, which varies continuously. Generally the smaller the PDOP number, the higher the data quality. The PDOP is a permanent part of the recorded data and is also included in the post processing procedures during reduction of the GPS observations to NAD 83. Where possible, the GPS base station has an ellipsoid height to an accuracy of two centimeters relative to the Continuously Operating Reference Stations (CORS) or the High Accuracy Reference Network (HARN), both operated by the National Geodetic Survey (NGS). Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: For all elevation data the vertical accuracy specification is +/- 15 centimeters and is referenced to NAVD 1988. This elevation data is intended primarily for use in hydrological modeling. It is collected as high accuracy, "bare earth" ground elevation. That is, the data are restricted to ground elevations only. "Bare earth" in the Everglades swamp environment is generally considered to be the layer of "muck" which will support a one pound weight on a bearing surface of approximately 5.3 square inches (2.6 inch circle). In non-swamp areas it is actual bare ground. Lineage: Process_Step: Process_Description: The process for creating digital elevation files consisted of the following steps: 1. Collection of GPS XYZ points in map area 3 during the pilot study started in FY 1995. 2. The GPS data were transformed from NAD83 geographic X, Y coordinates and NAVD88 elevation Z valuse to NAD83 UTM X, Y and NAVD88 Z coordinates via "Corpscon for Windows" from the U.S. Army Corps of Engineers. http://crunch.tec.army.mil/software/corpscon/corpscon.html 3. The coordinate data were imported into a geographic information system to create multiple geospatial data formats. 4. The ascii text file containing 1925 data records was aggregated and reformatted using custom shell scripts. 5. The shapefile-associated .dbf file was opened in MS Excel and saved as the comma-separated value file which also is available for download Process_Date: 200708 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Susan D. Price Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 521 National Center City: Reston State_or_Province: VA Postal_Code: 20192 Country: USA Contact_Voice_Telephone: 703 648 6692 Contact_Electronic_Mail_Address: sprice@usgs.gov Spatial_Data_Organization_Information: Indirect_Spatial_Reference: south east coast of Florida Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Entity point Point_and_Vector_Object_Count: 1925 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 17 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.9996 Longitude_of_Central_Meridian: -81 Latitude_of_Projection_Origin: 0 False_Easting: 500000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: Coordinate Pair Coordinate_Representation: Abscissa_Resolution: 400 Ordinate_Resolution: 400 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Datum_Name: North American Vertical Datum of 1988 Altitude_Resolution: .01 Altitude_Distance_Units: meters Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: ELEV_M Entity_Type_Definition: ground surface elevation in meters Entity_Type_Definition_Source: USGS Detailed_Description: Entity_Type: Entity_Type_Label: X_UTM Entity_Type_Definition: UTM X coordinate in meters for the data collection point Entity_Type_Definition_Source: USGS Detailed_Description: Entity_Type: Entity_Type_Label: Y_UTM Entity_Type_Definition: UTM Y coordinate in meters for the data collection point Entity_Type_Definition_Source: USGS Detailed_Description: Entity_Type: Entity_Type_Label: QUAD_NAME Entity_Type_Definition: The name of the USGS 1:24, 000-scale topographic quadrangle in which the point falls Entity_Type_Definition_Source: USGS Detailed_Description: Entity_Type: Entity_Type_Label: SUR_METHOD Entity_Type_Definition: type of surveying method - truck Entity_Type_Definition_Source: USGS Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Heather S.Henkel Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: 600 Fourth St. South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727 803-8747 ext 3028 Contact_Facsimile_Telephone: 727 803-2030 Contact_Electronic_Mail_Address: hhenkel@usgs.gov Resource_Description: Truck Distribution_Liability: No warrantees are implied or explicit for the data Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ASCII Format_Version_Date: 1985 Format_Specification: .csv Format_Information_Content: comma-separated values for elevations in map area 3 Transfer_Size: 0.08 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://sofia.usgs.gov/exchange/desmond/desmondelev.html Access_Instructions: Files may be downloaded from the SOFIA website Digital_Form: Digital_Transfer_Information: Format_Name: zip Format_Version_Number: unknown Format_Specification: shp.zip Format_Information_Content: ArcGIS shapefile and associated files for the elevations collected by truck File_Decompression_Technique: file must be unzipped before use Transfer_Size: 0.051 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://sofia.usgs.gov/exchange/desmond/desmondelev.html Access_Instructions: Data may be downloaded from the SOFIA website Fees: none Metadata_Reference_Information: Metadata_Date: 20071024 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Heather Henkel Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing and physical address Address: 600 Fourth Street South City: St. Petersburg State_or_Province: FL Postal_Code: 33701 Country: USA Contact_Voice_Telephone: 727 803-8747 ext 3028 Contact_Facsimile_Telephone: 727 803-2030 Contact_Electronic_Mail_Address: sofia-metadata@usgs.gov Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998