Identification_Information:
  Citation:
    Citation_Information:
      Originator: Ellen A. Raabe, Melanie S. Harris, Ramesh L. Shrestha, and William E. Carter
      Publication_Date: 2008
      Title: Derivation of ground surface and vegetation in a coastal Florida wetland with airborne laser technology
      Series_Information:
        Series_Name: Open-File Report
        Issue_Identification: 2008-1125
      Publication_Information:
        Publication_Place: St. Petersburg, FL
        Publisher: U.S. Geological Survey
  Description:
    Abstract: The topography and vegetation of marsh-dominated coastal lowlands were mapped from airborne laser data points collected on the Gulf Coast of Florida near Cedar Key, 17 August 1999. Bare-earth and canopy-height models, land-cover categories, shoreline, and topographic profiles were derived from the laser-altimetry data. Digital surface models (DSM) were developed using low- and high-point filters to separate ground surface and vegetation canopy intercepts. In a non-automated process, the landscape was partitioned into functional landscape units to model key landscape features in discrete processing steps.  The final digital ground surface elevation models are representations of topographic relief beneath canopies of tidal marsh and coastal forest.  Bare-earth models approximate field-surveyed heights by + or - 0.17 m in the open marsh and + or - 0.22 m under thick marsh or forest canopy. Classification of coastal land-cover employed a combination of ground surface DSM, canopy height DSM, and intensity values. Additional information was derived by extracting topographic profiles and shoreline shapefiles. The derived products demonstrate the capability to identify unique components of the coastal system from laser altimetry. The limited laser returns from this early instrument resulted in infrequent ground penetration in thick vegetation. New laser-altimeter instrumentation, multiple returns per pulse, and full-waveform systems can provide improved topographic mapping with this technology.
    Purpose: The USGS is providing surface models, land cover, and shoreline data for  coastal lowlands near Cedar Key, Florida. Data was acquired from airborne laser to provide an example of the technology for monitoring wetland regions. Remote data acquisition has the potential to improve our knowledge of coastal topography and habitats, and to enhance coastal resource management. Because the very nature of a wetland system presents difficulties for access and data collection, airborne coverage from remote sensors has become an accepted alternative for monitoring wetland regions.
    Supplemental_Information:
      ALSM data were collected at three locations: Lukens Creek (6 sq km), Waccasassa (4 sq km), and Bird Creek (4.5 sq km), on August 17, 1999, between 11:30 am and 2:30 pm. Tide range for the flights was -0.312 to -0.024 meters MSL. The altitude of the flight was 500 m, with 344 m swath width (65% overlap). Laser altimetry data was processed with proprietary software from Operational Technologies Corporation. Horizontal coordinates (x,y) were provided as Universal Transverse Mercator (UTM) 17R NAD83. Elevation, z-values, were provided as NAVD88 orthometric heights (meters). 

      Digital Surface Models (DSMs), or surface grids, were developed in phases.  Flight paths were pieced together to create a mosaic for each site. The team developed an interactive filter program to extract lowest or highest points (z-values) from each mosaic with adjustable parameters specified by an analyst. Surfaces were created with ordinary kriging to interpolate low-point-filter (LPF) and high-point-filter (HPF) results. Break points for landscape elements were: LPF -0.5><0.2 m; LPF >0.2 m and HPF <1.9m; and HPF>1.9 m. Bare-earth DSM was modeled from LPF series. Shoreline was extracted from from the 0.2 m contour in bare-earth DSM. Canopy height DSM was modeled from HPF surface minus bare-earth surface. Incomplete canopy penetration during summer resulted in minor discrepancies. Land cover was derived from an unsupervised classification using bare-earth and canopy height DSMs and intensity values. 

      Details on methods and results are available in U.S. Geological Survey OFR 2008-1125 (Raabe et al., 2008). The data set includes: GeoTIFF format raster files for bare-earth DSM and canopy height DSM at Lukens Creek ("luk_dsm" and "luk_veg") and the Waccasassa area. Both Bird Creek and Waccasassa River flight lines are contained in the "wac_dsm" and "wac_veg" files. Values in the DSMs are 10x orthometric heights or canopy heights for ease of application in 8-bit raster files. Intensity-value GeoTIFF files were also released. Shoreline shape files were derived from the 0.2 m contour in the bare-earth DSM. Land cover classifications were provided as GeoTIFF files. ArcMAP layer files were developed to match user-displays with Figures provided in USGS OFR 2008-1125.

      Suggested citation: Raabe, E.A., Harris, M.S., Shrestha, R.L., and Carter, W.E., 2008, Derivation of ground surface and vegetation in a coastal Florida wetland with airborne laser technology, U.S. Geological Survey Open-File Report 2008-1125, 41 p.
  Time_Period_of_Content:
    Time_Period_Information:
      Single_Date/Time:
        Calendar_Date: August 17, 1999
        Time_of_Day: 11:30am - 2:10pm
    Currentness_Reference: ground condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -83.071869
      East_Bounding_Coordinate: -82.762966
      North_Bounding_Coordinate: 29.235163
      South_Bounding_Coordinate: 29.145725
  Keywords:
    Theme:
      Theme_Keyword: laser altimetry
      Theme_Keyword: digital surface model
      Theme_Keyword: airborne laser swath mapping (ALSM)
      Theme_Keyword: light detection and ranging (LIDAR)
      Theme_Keyword: wetland
      Theme_Keyword: tidal creeks
      Theme_Keyword: coastal habitats
      Theme_Keyword: plant canopy
    Place:
      Place_Keyword: Cedar Key
      Place_Keyword: Lukens Creek
      Place_Keyword: Waccasassa River
      Place_Keyword: Bird Creek
      Place_Keyword: Levy County
      Place_Keyword: Waccasassa Bay
      Place_Keyword: Florida Gulf Coast
    Stratum:
      Stratum_Keyword: intertidal zone
      Stratum_Keyword: terrestrial
      Stratum_Keyword: coastal lowland
      Stratum_Keyword: canopy height
    Temporal:
      Temporal_Keyword: 17 August 1999
  Access_Constraints: It is strongly recommended that these data are directly acquired from the distributor described above or from another USGS server and not indirectly through other sources which may have changed the data in some way. The distributor makes no claim as to the data's suitability for other purposes.
  Use_Constraints: Acknowledgement of the U.S. Geological Survey, St. Petersburg, Florida, as a data source would be appreciated in products developed from these data, and such acknowledgement as is standard for citation and legal practices for data source is expected by users of these data. Sharing new data layers developed directly from these data would be appreciated by U.S. Geological Survey, Florida Integrated Science Center, Center for Coastal and Watershed Studies, St. Petersburg, FL staff. Users should be aware that comparison with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection procedures, and computer processes over time. The distributor shall not be liable for improper or incorrect use of these data, based on the description of appropriate/inappropriate uses described in this metadata document. These data are not legal documents and are not to be used as such.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Ellen A. Raabe
        Contact_Organization: U.S. Geological Survey
      Contact_Position: Physical Scientist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 600 4th St. S
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727-803-8747 ext. 3039
      Contact_Facsimile_Telephone: 727-803-2030
      Contact_Electronic_Mail_Address: eraabe@usgs.gov
  Data_Set_Credit: U.S. Geological Survey, St. Petersburg, FL and Civil Engineering Department, UF, Gainesville, FL
  Native_Data_Set_Environment: Developed with computer software Optech, UF filter script, Surfer, PCI Geomatica, ERDAS Imagine, & ArcMAP
Data_Quality_Information:
  Lineage:
    Source_Information:
      Source_Citation:
        Citation_Information:
          Originator: University of Florida, Department of Civil Engineering
          Publication_Date: 1999
          Title: Airborne Laser Swath Mapping
          Geospatial_Data_Presentation_Form: tabular digital data
          Other_Citation_Details: W.E., Carter and R.L., Shrestha
      Type_of_Source_Media: CD-ROM
      Source_Time_Period_of_Content:
        Time_Period_Information:
          Single_Date/Time:
            Calendar_Date: 17 August 1999
        Source_Currentness_Reference: ground condition
      Source_Contribution: x,y,z values processed with Optech proprietary software
Spatial_Data_Organization_Information:
  Direct_Spatial_Reference_Method: Raster
  Raster_Object_Information:
    Raster_Object_Type: Pixel
    Row_Count: 4900
    Column_Count: 3720
    Vertical_Count: 1
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: 0.999600
            Longitude_of_Central_Meridian: -81.000000
            Latitude_of_Projection_Origin: 0.000000
            False_Easting: 500000.000000
            False_Northing: 0.000000
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 2.000000
          Ordinate_Resolution: 2.000000
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: D_WGS_1984
      Ellipsoid_Name: WGS_1984
      Semi-major_Axis: 6378137.000000
      Denominator_of_Flattening_Ratio: 298.257224
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates x10
Distribution_Information:
  Distribution_Liability: Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from a USGS server, and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the contents of the metadata document associated with these data. U.S. Geological Survey shall not be held liable for improper or incorrect use of the data, including, without limitations, the implied warranties or merchantability and fitness for a particular purpose. Also, use of trade names or commerical products in these metadata is solely for the purpose of providing specific information, and does not imply recommendation or endorsement by the U.S. Government. Any downloading and use of these data signifies a user's agreement to comprehension and compliance of the U.S. Geological Survey Standard Disclaimer. Insure all portions of metadata are read and clearly understood before using these data in order to protect both user and U.S. Geological Survey interests.
Metadata_Reference_Information:
  Metadata_Date: 20080424
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Ellen Raabe
        Contact_Organization: U.S. Geological Survey
      Contact_Position: Physical Scientist
      Contact_Address:
        Address_Type: mailing address
        Address: 600 4th St. S
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: United States of America
      Contact_Voice_Telephone: 727-803-8747 x3039
      Contact_Electronic_Mail_Address: eraabe@usgs.gov
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Access_Constraints: There are no access limitations on acquiring the metadata document. Metadata can be accessed through the U.S. Geological Survey.
  Metadata_Use_Constraints: Acknowledgement of the U.S. Geological Survey as the metadata source would be appreciated. Please cite the original metadata when using portions of the record to create a similar record for slightly altered data for reprojection or subsetting.