Identification_Information:
  Citation:
    Citation_Information:
      Originator: U.S. Geological Survey
      Publication_Date: 2012
      Title: EAARL Coastal Topography--Alligator Point, Louisiana, 2010
      Edition: first
      Geospatial_Data_Presentation_Form: remote-sensing image
      Series_Information:
        Series_Name: U.S. Geological Survey Data Series
        Issue_Identification: 665
      Publication_Information:
        Publication_Place: St. Petersburg, FL
        Publisher: U.S. Geological Survey
  Description:
    Abstract: A digital elevation model (DEM) of a portion of Alligator Point, Louisiana, was produced from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey (USGS). Elevation measurements were collected over the area using the Experimental Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 50 meters per second at an elevation of approximately 300 meters, resulting in a laser swath of approximately 240 meters with an average point spacing of 2-3 meters. The EAARL, developed originally by the National Aeronautics and Space Administration (NASA) at Wallops Flight Facility in Virginia, measures ground elevation with a vertical resolution of +/-15 centimeters. A sampling rate of 3 kilohertz or higher results in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development. The Alligator Point data provided represent the last return pulses and were processed and filtered for bare-earth topography. However, in low-lying and emerging vegetation environments, bare-earth topography is not necessarily discernible from the last-return pulses. The difference in water levels between data collections on March 5 and 6 resulted in elevation variations in the merged data.
    Purpose: The purpose of this project was to produce highly detailed and accurate digital elevation maps of a portion of Alligator Point, Louisiana, for use as a management tool and to make these data available to natural-resource managers and research scientists.
    Supplemental_Information:
      Raw lidar data are not in a format that is generally usable by resource managers and scientists for scientific analysis. Converting dense lidar elevation data into a readily usable format without loss of essential information requires specialized processing. The U.S. Geological Survey's Coastal and Marine Geology Program (CMGP) has developed custom software to convert raw lidar data into a GIS-compatible map product to be provided to GIS specialists, managers, and scientists. The primary tool used in the conversion process is Airborne Lidar Processing System (ALPS), a multi-tiered processing system developed by a USGS-NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL to georeferenced spot (x,y,z) returns for "first surface" and "bare earth" topography. The terms first surface and bare earth refer to the digital elevation data of the terrain, but while first-surface data include vegetation, buildings, and other manmade structures, the bare-earth data do not. The zero crossing of the second derivative (that is, detection of stationary points) is used to detect the first return, resulting in "first surface" topography, while the trailing edge algorithm (that is, the algorithm searches for the location prior to the last return where direction changes along the trailing edge) is used to detect the range to the last return, or "bare earth" (the first and last returns being the first and last significant measurable portion of the return pulse). Statistical filtering, known as the Random Consensus Filter (RCF), is used to remove false bottom returns and other outliers from the EAARL topography data. The filter uses a grid of non-overlapping square cells (buffer) of user-defined size overlaid onto the original point cloud. The user also defines the vertical tolerance (vertical width) based on the topographic complexity and point-sampling density of the data. The maximum allowable elevation range within a cell is established by this vertical tolerance. An iterative process searches for the maximum concentration of points within the vertical tolerance and removes those points outside of the tolerance (Nayegandhi and others, 2009). These data are then converted to the North American Datum of 1983 and the North American Vertical Datum of 1988 (using the GEOID09 model). Each file contains data located in a 2-kilometer by 2-kilometer tile, where the upper-left bound can be assessed quickly through the filename. The first 3 numbers in the filename represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM northing coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, ct_e123_n4567_16).

      The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMGP's Decision Support for Coastal Science and Management project. Processed data products are used by the U.S. Geological Survey CMGP's National Assessments of Coastal Change Hazards project to quantify the vulnerability of shorelines to coastal change hazards such as severe storms, sea-level rise, and shoreline erosion and retreat.
  Time_Period_of_Content:
    Time_Period_Information:
      Multiple_Dates/Times:
        Single_Date/Time:
          Calendar_Date: 20100305
        Single_Date/Time:
          Calendar_Date: 20100306
    Currentness_Reference: ground condition
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: None planned
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -89.84439692
      East_Bounding_Coordinate: -89.63364531
      North_Bounding_Coordinate: 30.14688807
      South_Bounding_Coordinate: 30.01639018
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: ISO 19115 Topic Category
      Theme_Keyword: elevation
    Theme:
      Theme_Keyword_Thesaurus: General
      Theme_Keyword: Airborne Lidar Processing System
      Theme_Keyword: ALPS
      Theme_Keyword: Digital Elevation Model
      Theme_Keyword: DEM
      Theme_Keyword: EAARL
      Theme_Keyword: Experimental Advanced Airborne Research Lidar
      Theme_Keyword: laser altimetry
      Theme_Keyword: lidar
      Theme_Keyword: Pilatus PC-6
      Theme_Keyword: remote sensing
      Theme_Keyword: topography
    Place:
      Place_Keyword_Thesaurus: Geographic Names Information System
      Place_Keyword: Alligator Point
      Place_Keyword: Louisiana
      Place_Keyword: United States
      Place_Keyword: North America
    Stratum:
      Stratum_Keyword_Thesaurus: General
      Stratum_Keyword: Coastal Topography
    Temporal:
      Temporal_Keyword_Thesaurus: General
      Temporal_Keyword: 2010
  Access_Constraints: None
  Use_Constraints: The U.S. Geological Survey requests to be acknowledged as the originator of these data in future products or derivative research.
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Jamie M. Bonisteel-Cormier
        Contact_Organization: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
      Contact_Position: Lidar Analyst
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 600 4th Street South
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727 803-8747 (x3124)
      Contact_Facsimile_Telephone: 727 803-2031
      Contact_Electronic_Mail_Address: jcormier@usgs.gov
      Hours_of_Service: M-F, 9:00-5:00 EST
  Data_Set_Credit: Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.
  Security_Information:
    Security_Classification_System: Unclassified
    Security_Classification: Unclassified
    Security_Handling_Description: None
  Native_Data_Set_Environment: Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.3.1.3000
  Cross_Reference:
    Citation_Information:
      Originator: Nayegandhi, A., Brock, J.C., and Wright, C.W.
      Publication_Date: 2009
      Title: Small footprint, waveform-resolving lidar estimation of submerged and subcanopy topography in coastal environments
      Series_Information:
        Series_Name: International Journal of Remote Sensing
        Issue_Identification: 30(4), p. 861-878
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report: The expected accuracy of the measured variables is as follows: attitude within 0.07 degree, 3 centimeters nominal ranging accuracy, and vertical elevation accuracy of +/-15 centimeters for the topographic surface. Quality checks are built into the data-processing software.
  Logical_Consistency_Report: Each file contains data located in a 2-kilometer by 2-kilometer tile where the upper-left bound can be assessed quickly through the filename. The first 3 numbers in the filename represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM northing coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, ct_e123_n4567_16).
  Completeness_Report: Several regions of the dataset are labeled as "No Data," which corresponds to a cell value of -32767 meters in the GeoTIFF file. These "No Data" areas are a result of the survey not covering a particular region, optical water depth of greater than 1.5 Secchi disc depths, or the manual removal of lidar processing artifacts. This metadata file is generalized; each data file on this DVD has its own corresponding metadata file.
  Positional_Accuracy:
    Horizontal_Positional_Accuracy:
      Horizontal_Positional_Accuracy_Report: Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy.
    Vertical_Positional_Accuracy:
      Vertical_Positional_Accuracy_Report: Typical vertical elevation accuracies for these data are consistent with the point elevation data, +/-15 centimeters. However, a ground-control survey is not conducted simultaneously with every lidar survey. Vertical accuracies may vary based on the type of terrain (for example, inaccuracies may increase as slope increases or with the presence of extremely dense vegetation) and the accuracy of the GPS and aircraft-attitude measurements.
  Lineage:
    Process_Step:
      Process_Description: The data were collected using a Pilatus PC-6 aircraft. The Experimental Advanced Airborne Research Lidar (EAARL) laser scanner collects the data using a green-wavelength (532-nanometer) raster scanning laser, while a digital camera acquires a visual record of the flight. The data are stored on hard drives and archived at the U.S. Geological Survey office in St. Petersburg, Florida. The navigational data are processed and, along with the raw data, are then downloaded into ALPS, or the Airborne Lidar Processing System (20101022 - 20110107). Data are converted from units of time to x,y,z points for elevation and formatted into .las and .xyz files. The derived surface data can then also be converted into raster data (GeoTIFFs).
      Process_Date: 20100305 through 20110107
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Jamie M. Bonisteel-Cormier
            Contact_Organization: U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
          Contact_Position: Lidar Analyst
          Contact_Address:
            Address_Type: mailing and physical address
            Address: 600 4th Street South
            City: St. Petersburg
            State_or_Province: FL
            Postal_Code: 33701
            Country: USA
          Contact_Voice_Telephone: 727 803-8747 (x3124)
          Contact_Electronic_Mail_Address: jcormier@usgs.gov
          Hours_of_Service: M-F, 8:00-4:00 EST
    Process_Step:
      Process_Description: Metadata imported into ArcCatalog 9.3.1.3000 from XML file.
      Process_Date: 20110401
      Process_Contact:
        Contact_Information:
          Contact_Person_Primary:
            Contact_Person: Xan Fredericks
            Contact_Organization: Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
          Contact_Position: Geologist/GIS Analyst/Metadata Specialist
          Contact_Address:
            Address_Type: mailing and physical address
            Address: 600 4th Street South
            City: St. Petersburg
            State_or_Province: FL
            Postal_Code: 33701
            Country: USA
          Contact_Voice_Telephone: 727 803-8747 (x3086)
          Contact_Electronic_Mail_Address: afredericks@usgs.gov
          Hours_of_Service: M-F, 8:00-4:00 EST
Spatial_Data_Organization_Information:
  Indirect_Spatial_Reference: Tiling Index
  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: 16
          Transverse_Mercator:
            Scale_Factor_at_Central_Meridian: 0.999600
            Longitude_of_Central_Meridian: -87.000000
            Latitude_of_Projection_Origin: 0
            False_Easting: 500000.000000
            False_Northing: 0
      Planar_Coordinate_Information:
        Planar_Coordinate_Encoding_Method: row and column
        Coordinate_Representation:
          Abscissa_Resolution: 2.500000
          Ordinate_Resolution: 2.500000
        Planar_Distance_Units: meters
    Geodetic_Model:
      Horizontal_Datum_Name: North American Datum of 1983
      Ellipsoid_Name: Geodetic Reference System 80
      Semi-major_Axis: 6378137.000000
      Denominator_of_Flattening_Ratio: 298.25722210100002
  Vertical_Coordinate_System_Definition:
    Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.15
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
Entity_and_Attribute_Information:
  Overview_Description:
    Entity_and_Attribute_Overview: Each pixel of the encoded GeoTIFF has an explicit elevation value associated with it. The GeoTIFF grid is encoded with the interpolated elevation value at a 2.5-meter resolution. The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 6 meters x 6 meters; vertical tolerance (vertical width) = 25 centimeters. The GeoTIFFs are created using Delauney triangulation, followed by linear interpolation based on routines in the ITT VIS Interactive Data Language (IDL) code.
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/2009/1078/
Distribution_Information:
  Distributor:
    Contact_Information:
      Contact_Organization_Primary:
        Contact_Organization: U.S. Geological Survey
        Contact_Person: Emily S. Klipp
      Contact_Position: GIS Analyst
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 600 4th Street South
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727 803-8747 (x3089)
      Hours_of_Service: M-F, 8:30-4:30 EST
  Resource_Description: DS 665
  Distribution_Liability: This DVD publication was prepared by an agency of the United States Government. 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 display 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.  The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, expressed or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights.
  Standard_Order_Process:
    Digital_Form:
      Digital_Transfer_Information:
        Format_Name: GeoTIFF
        Format_Version_Number: 2
        Format_Specification: GeoTIFF
      Digital_Transfer_Option:
        Offline_Option:
          Offline_Media: DVD
          Recording_Format: DVD
    Fees: Vary
    Ordering_Instructions: Contact U.S. Geological Survey.
    Turnaround: Vary
  Custom_Order_Process: Contact U.S. Geological Survey for details.
  Available_Time_Period:
    Time_Period_Information:
      Multiple_Dates/Times:
        Single_Date/Time:
          Calendar_Date: 20100305
        Single_Date/Time:
          Calendar_Date: 20100306
Metadata_Reference_Information:
  Metadata_Date: 20110503
  Metadata_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Xan Fredericks
        Contact_Organization: Jacobs Technology, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
      Contact_Position: Geologist/GIS Analyst/Metadata Specialist
      Contact_Address:
        Address_Type: mailing and physical address
        Address: 600 4th Street South
        City: St. Petersburg
        State_or_Province: FL
        Postal_Code: 33701
        Country: USA
      Contact_Voice_Telephone: 727 803-8747 (x3086)
      Contact_Electronic_Mail_Address: afredericks@usgs.gov
      Hours_of_Service: M-F, 8:00-4:00 EST
  Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
  Metadata_Standard_Version: FGDC-STD-001-1998
  Metadata_Time_Convention: local time
  Metadata_Extensions:
    Online_Linkage: http://www.esri.com/metadata/esriprof80.html
    Profile_Name: ESRI Metadata Profile