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2008 St. Johns County, FL Countywide Lidar

Airborne terrestrial LiDAR was collected for St. Johns County, FL. System Parameters/Flight Plan. The LiDAR system acquisition parameters were developed based on a maximum average ground sample distance of 2.1 feet. A Leica ALS50 LiDAR sensor was used for acquisition. Acquisition specifications for the sensor follows: Field of View (full angle) - 24 degrees, Nominal flight altitude (AGL) - 3000 feet, Airspeed - 130 mph (113 knots), Laser pulse rate - 100,000 Hz, Nominal swath width (on ground) - 1275 feet, Maximum cross track point spacing - 2.07 feet, Maximum along track point spacing - 4.30 feet, Average point spacing - 1.67 feet, Flight line spacing - 970.47 feet, Side overlap - 23.91 percent. LiDAR System Calibration. Prior to the LiDAR acquisition, the system underwent a calibration to verify the operational accuracy and misalignment angles. Boresight calibrations were performed for the LiDAR system at the beginning and end of each flight mission. LiDAR Data Acquisition. LiDAR data acquisition only occurred when the sky was sufficiently clear of clouds, smoke, and atmospheric haze. The LiDAR data was processed immediately after the acquisition to verify the coverage had no voids. GPS/Inertial Measurement Unit (IMU) Post Processing. The GPS and IMU data was post processed using differential and kalman filter algorithms to derive a best estimate of trajectory. The quality of the solution was verified to be consistent with the accuracy requirements of the project. LiDAR Processing and Classification. The LiDAR data was post processed and verified to be consistent with the project requirements in terms of post spacing and absence of artifacts. The point cloud underwent classification to determine bare-earth points (class 2), noise points (class 7), water returns (class 9), and unclassified data (class 1). Class 12 contains LiDAR points removed from the overlap region between adjacent flight lines.

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    Distribution Formats
    • LAZ
    Distributor Distributor information not available
    Point of Contact St. Johns County GIS Division
    Documentation links not available.
    • St. Johns County, FL GIS Division
      Publisher information not available.
    • publication: 2009-01-06
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: As needed
    Supplemental Information: Project Title- Countywide Digital Contour Mapping; Vendor Name- Woolpert, Inc. The Final QA/QC Quantitative Assessment Report for this data set may be viewed at: The Final Ground Control Survey Report (more detail given to field activities, process, etc.) may be viewed at: An additional Aerial Triangulation Report may be accessed at:
    Purpose: The DTM was developed to support the development and maintenance of the St. Johns County Countywide Digital Contour Mapping Project.
    Time Period: 2008-02-14 2008-02-19  to  2008-02-17 2008-02-21
    Spatial Reference System:
    Spatial Bounding Box Coordinates:
    N: 30.253509
    S: 29.621834
    E: -81.212177
    W: -81.669741
    Spatial Coverage Map:
    • Bathymetry/Topography
    • lidar
    • Digital Elevation Model
    • DEM
    • remote sensing
    • topography
    • US
    • Florida
    • St. Johns County
    Use Constraints No constraint information available
    Fees Fee information not available.
    Lineage Statement Lineage statement not available.
    • Woolpert, Inc.
    • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
    Processing Steps
    • Ground (class 2) LAS points were extracted in ArcMap, using a Woolpert Team-developed VB Script, and loaded into the MASSPOINTS feature class for each area's Geodatabase as multipoint geometry.
    • The NOAA Coastal Services Center received the data in LAS format. The files contained Lidar elevation and intensity measurements. The data were projected in State Plane coordinates (NAD83; Florida East) and referenced to the North American Vertical Datum of 1988 (NAVD88) using the Geoid03 model. The following processes were performed to make the data available within the Digital Coast: 1. The data were converted from state plane (NAD83; Florida East) to geographic coordinates (NAD83). 2. The data were converted from NAVD88 (orthometric) heights to GRS80 (ellipsoidal) heights using the Geoid03 model. 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 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 ( 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: 2013-06-14

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