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2007 Southwest Florida Water Management District (SWFWMD) LiDAR: Hernando County

browse graphicThis kmz file shows the extent of coverage for the 2007 SWFWMD Hernando County, FL lidar data set.
This dataset is one component of a digital terrain model (DTM) for the Southwest Florida Water Management Districts FY2006 Digital Orthophoto (B089) and LiDAR Project (L776) encompassing approximately 462 square miles in Hernando County, Florida. This dataset is comprised of 530 LiDAR files, based on the DISTRICT 5,000' by 5,000' sheet index system in the LAS version 1.1 file format. LiDAR acquisition dates were January 11 through January 16, 2007. The raw data was collected at an average ground sample distance of 2.1 feet. Other components of the DTM include a personal geodatabase in accordance with the SWFWMD 2006 Topographic Database Design containing: obscured vegetation polygons; road overpass polygons; road breaklines; soft feature breaklines; water body polygons; coastal shorelines; hydrographic features breaklines; island polygons; and 1-foot contours. Final products include FEMA-compliant LIDAR-derived DTM data and 1-foot contours (for cartographic visualization purposes only) meeting or exceeding National Map Accuracy Standards for 2-foot contours.

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 Mapping and GIS
    Southwest Florida Water Management District
    (352) 796-7211
    Associated Resources
    • Lidar Final Report
    Originator
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Originator
    • Southwest Florida Water Management District (SWFWMD)
    Publisher
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2008-02-18
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: As needed
    Supplemental Information: Project Title: FY2007 Digital Orthophoto (B089) and LiDAR Project (L776) Purchase Order: 07POSOW0322 Work Order Name: North District One-Foot Orthophoto and LiDAR - Work Order 1 Vendor Name: Woolpert, Inc.
    Purpose: The DTM was developed to support the District's regulatory, land management and acquisition, planning, engineering, and habitat restoration projects.
    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: 2007-01-11  to  2007-01-16
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 28.350110
    S: 28.308789
    E: -81.848175
    W: -81.925929
    Spatial Coverage Map:
    Themes
    • Bathymetry/Topography
    • LiDAR LAS digital terrain model
    • Terrain
    • Model
    • Elevation
    • Surface
    • Laser
    Places
    • US
    • Florida
    • Southwest Florida
    • Hernando County
    Use Constraints No constraint information available
    Fees Fee information not available.
    Lineage Statement Lineage statement not available.
    Processor
    • Woolpert, Inc.
    • 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 LiDAR data was acquired using a Leica ALS50 from an average altitude of 2,400-feet above ground level to provide an average ground sample distance of 2.1-feet. First and last return data was collected along with the signal return intensity. Two redundant airborne GPS bases stations were utilized during the data acquisition with maximum line-of-sight distance between the base station and aircraft of 20-km. The LiDAR data was reduced using Grafnav (Waypoint Consulting) for GPS post-processing, PosProc (Applanix Crop) for IMU processing, ALS50 Post Processor (LH Systems) to initial LiDAR processing, TerraScan (Terrasolid) for initial point classification, and proprietary Woolpert developed software for refining the point classification and QC. The LiDAR data was reviewed in 3D using a digital photogrammetric work station using ADS40 digital stereo imagery. During the production process, LiDAR data gaps between the flight lines were observed. These gaps between flight lines were corrected by adding photogrametrically compiled mass points. These points are classified as class 10, in the LAS file. In the areas with the compiled mass points, it may be noted that the mass points are not as dense the areas with complete LiDAR coverage. The mass points were compiled at a sufficient density to define the surface to contract specifications. The LAS files contain 5 classifications: 1 = unclassified; 2 = ground; 9 = water; 10 = photogrammetric masspoints; and 11 = swamp and/or wetlands. The class 1 consists of all points not on the ground. Class 2 consists of bare earth points. Class 9 consists of points within water polygons. Class 11 consists of points within swamps and/or wetlands. Class 10 consists of supplementary mass points that were photogrametrically compiled on points features such as peaks or pits, and LiDAR data gaps. These points were created to maintain the accuracy of the DTM. 3D breaklines were collected at the digital photogrammetric workstation during the LiDAR data review. These breaklines were delineated to insure the DTM is hydrologically correct. Hydrologically Enforced Elevation Data is defined as "Hydorenforced TINS, DEMS, or contours ensure that top surfaces of bridges and culverts are cut by stream breaklines so that computer models will accurately represent drainage flow" per FEMA's Appendix A A.4.10. The breaklines were collected for hydrologically significant features as appropriate to support the development of the generation of 2-foot contours meeting National Map Accuracy Standards. The following breakline features were classified and separated: Closed Water Body Features, Linear Hydrographic Features, Coastal Shorelines, Road Features, Soft Features, Obscured Vegetated Areas, Island Features, Overpasses, and Bridges. Per contract specifications, culverts were not collected as part of this project. Therefore continuity of hydrographic features may not be consistent. During final data production and analysis, the occurrence of mound type features in the data set was noted. These areas were checked, and verified to be above ground septic systems. For a complete description of survey methods, processing methods, software, system parameters, and accuracy analysis, see the Florida MTS Report of Specific Purpose Survey, SWFWMD MTS Report of DOI Survey, FY2007 Digital Orthophoto and LiDAR (B089 & L776 (dated 4/31/2008).
    • The NOAA Coastal Services Center (CSC) received the files in LAS format. The files contained Lidar intensity and elevation measurements. The data was in Florida State Plane Projection and NAVD88 vertical datum. CSC performed the following processing to the data to make it available within the LDART Retrieval Tool (LDART): 1. The data were converted from Florida State Plane West coordinates to geographic coordinates. 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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