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2007 Florida Division of Emergency Management (FDEM) Lidar Project: Nassau County

browse graphicThis kmz file shows the extent of coverage for the 2007 FDEM Nassau County, FL lidar data set.
This report pertains to a Specific Purpose LiDAR Survey of Nassau County, Florida. The LiDAR aerial acquisition was conducted by Terrapoint USA between August 18, 2007 and September 4, 2007, and the breaklines and contours were subsequently generated by Dewberry. The PDS team is under contract HS-34-14-00-22-469 with the Florida Division of Emergency Management (FDEM) and offered LiDAR and derived products as an add-on agreement with Nassau County at the same rates as negotiated for the FDEM contract and utilizing the same Baseline Specifications from FDEM. The LiDAR dataset of Nassau County was acquired by Terrapoint USA and processed to a bare-earth digital terrain model (DTM) in accordance with FDEM Baseline Specifications. Detailed breaklines and contours were also produced by the PDS team. Each tile covers an area of 5000 ft by 5000 ft. The FDEM Baseline Specifications require a maximum LiDAR post spacing of 4 feet, i.e., an average point density of less than 1 point per square meter. However, the PDS team required a much higher point density of its subcontractors in order to increase the probability of penetrating dense foliage; with nominal post spacing of 0.7 meters per flight line and 50% sidelap between flight lines, the average point density is 4 points per square meter with higher point density there is a greater probability of penetrating dense vegetation and minimizing areas defined as "low confidence areas." LiDAR was delivered as a point cloud in LAS 1.1 format.

Cite this dataset when used as a source.

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    Distribution Formats
    • LAZ
    Distributor DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Point of Contact Florida Division of Emergency Management (FDEM)
    850-413-9969
    Associated Resources
    • Lidar Dataset Supplemental Information
    Originator
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Originator
    • Florida Division of Emergency Management (FDEM)
    Publisher
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2008-01-01
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: As needed
    Purpose: These data support the Florida Division of Emergency Management's (FDEM) development and maintenance of Regional Evacuation Studies, which include vulnerability assessments and assist disaster response personnel in understanding threats to Florida's citizens and visitors.
    Use Limitations
    • These data depict the elevations at the time of the survey and are only accurate for that time. Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Any conclusions drawn from analysis of this information are not the responsibility of NOAA or any of its partners. These data are NOT to be used for navigational purposes.
    Time Period: 2007-08-18  to  2007-10-04
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 30.306119
    S: 29.962468
    E: -84.083288
    W: -84.748761
    Spatial Coverage Map:
    Themes
    • Bathymetry/Topography
    • DTM
    • Elevation
    • Lidar
    Places
    • US
    • Florida
    • Nassau County
    Use Constraints No constraint information available
    Fees Fee information not available.
    Source Datasets
    • Lidar
      • Description of Source: Source Contribution: LiDAR dataset was used to create intensity stereopairs for 3D breakline compilation and for contour generation.Source Type: online
      • Temporal extent used:  2007-08-18  to  2007-10-15
    Lineage Statement Lineage statement not available.
    Processor
    • Terrapoint USA
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
    Processing Steps
    • The ABGPS, IMU, and raw Optech 3100ea LiDAR scans are integrated using Optech Incorporated's DASHMap, version 1.1 software, Terrascan software and Microstation software. The resultant file is in a LAS binary file format. The LAS file version 1.1 format can be easily transferred from one file format to another. It is a binary file format that maintains information specific to the LiDAR data (return#, intensity value, xyz, etc.). The resultant points are referenced to the NAD83 horizontal datum and GRS80 vertical datum. The date and time for each flight line can be determined using the Julian date and time. The Julian date is a continuous count of days and fractions since noon Universal Time on January 1, 4713 BCE on the Julian Calendar.
    • The unedited data are classified to facilitate the application of the appropriate feature extraction filters. A combination of proprietary filters are applied as appropriate for the production of bare earth digital terrain models (dtms). Interactive editing methods are applied to those areas where it is inappropriate or impossible to use the feature extraction filters, based upon the design criteria and/or limitations of the relevant filters. These same feature extraction filters are used to produce elevation height surfaces. The LiDAR mass points were delivered in American Society for Photogrammetry and Remote Sensing LAS 1.1 format. The header file for each dataset is complete as define by the LAS 1.1 specification. In addition the following fields are included (Precision reported in brackets): Class (Integer); GPS Week Time (0.0001 seconds); Easting (0.01 meter); Northing (0.01 meter); Elevation (0.01 meter); Echo Number (Integer 1 to 4); Echo (Integer 1 to 4); Intensity (8 Bit Integer); Flightline (Integer); Scan Angle (Integer Degree). The LAS files do not include overlap. The data was classified as follows: Class 1 = Unclassified. This class includes vegetation, buildings, noise etc. Class 2 = Ground Class 7 = Noise Class 9 = Water
    • The NOAA Coastal Services Center (CSC) received the files in las format. The files contained Lidar elevation and intensity measurements. The data were in projected in Florida State Plane Coordinates (East Zone, NAD83/HARN), and referenced to the orthometric datum of NAVD88 utilizing Geoid 03. CSC performed the following processing to the data to make it available within the Digital Coast: 1. The data were converted from State Plane Coordinates (NAD83/HARN) coordinates to geographic coordinates (NAD83). 2. The data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoid) heights using Geoid 03. 3. The LAS data were sorted by latitude and the headers were updated.
    • The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp transfer from the NOAA Coastal Services Center. The data are currently being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/. The data can be used to re-populate the system. The data are archived in LAS or LAZ format. The LAS format is an industry standard for LiDAR data developed by the American Society of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless compressed version of LAS developed by Martin Isenburg (http://www.laszip.org/). The data are exclusively in geographic coordinates (either NAD83 or ITRF94). The data are referenced vertically to the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most up to date geoid model when transforming to orthometric heights.

    Metadata Last Modified: 2013-06-07

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