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2012 USACE Post-Hurricane Sandy Topographic LiDAR: Eastern Long Island, New York

browse graphicThis kmz file shows the extent of coverage for the 2012 USACE Post-Hurricane Sandy Long Island lidar data set.
TASK ORDER NAME: EASTERN LONG ISLAND, NEW YORK LIDAR ACQUISITION FOR HURRICANE SANDY RESPONSE CONTRACT NUMBER: W912P9-10-D-0533 TASK ORDER NUMBER: W81C8X23208588 Woolpert Project Number: 72903 Q. USACE required high-resolution digital elevation data developed from airborne LiDAR technology for the Eastern Long Island, New York. The Area of Interest (AOI) consisted of one hundred sixteen (116) square miles in the North Atlantic Division. The final LiDAR data was delivered in a UTM projection tiling format, based on a modular layout. The tiles were clipped to eliminate overlap between adjacent tiles. The 1000 meter x 1000 meter tile file name was derived from the National Grid naming convention. The data originally was collected with the following specifications: LAS v1.2 classified point cloud NAD83 UTM Zone 18N Meters, NAVD88 GEOID12A Meters.

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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 US Army Corps of Engineers St. Louis District
    314-331-8389
    ted.e.stanton@usace.army.mil
    Documentation links not available.
    Originator
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Originator
    • US Army Corps of Engineers (USACE) St. Louis District
    Publisher
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2013-01-01
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: As needed
    Purpose: The data will be used by the USACE to generate digital elevation models and contours for use in, damage assessment to USACE projects, engineering design and design reviews, conservation planning, research, delivery, floodplain mapping, and hydrologic modeling utilizing LiDAR technology. The task order required that the LiDAR data was to be acquired within six (6) days of receiving Notice to Proceed (NTP). The project data will consist of high accuracy classified bare-earth LiDAR data in LAS format well as raster digital elevation models per task order requirements. The specifications are based upon the U.S. Geological Survey National Geospatial Program Lidar Base Specifications 1.0, which may be viewed at http://pub.usgs.gov/tm/11b4/.
    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: 2012-11-14  to  2012-11-15
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 41.149619
    S: 40.762295
    E: -71.855068
    W: -72.754241
    Spatial Coverage Map:
    Themes
    • LiDAR
    • LAS
    • Elevation
    Places
    • United States
    • New York
    • Long Island
    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
    • Using an Optech Gemini LiDAR Sensor, 21 flight lines of high density data, at a nominal pulse spacing (NPS) of 1 meter, were collected along the Eastern Long Island, New York (approximately one hundred sixteen (116) square miles). Data Acquisition Height = 5,500 feet AGL - Aircraft Speed = 125 Knots. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of two (2) missions were flown during a period from November 14, 2012 through November 15, 2012. One airborne global positioning system (GPS) base station was used in support of the LiDAR data acquisition. Eighteen (18) ground control points were surveyed through static methods. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid12A. Data for the task order is referenced to the UTM Zone 18N, North American Datum of 1983 (NAD83), and NAVD88, in Meters. Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. In addition to the LAS deliverables, one layer of coverage was delivered in the ArcGrid Format: bare-earth.
    • The LiDAR system calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of LiDAR data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw LiDAR data is reduced using the refined misalignment angles.
    • Once the data acquisition and GPS processing phases are complete, the LiDAR data was processed immediately to verify the coverage had no voids. 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.
    • The individual flight lines were inspected to ensure the systematic and residual errors have been identified and removed. Then, the flight lines were compared to adjacent flight lines for any mismatches to obtain a homogenous coverage throughout the project area. The point cloud underwent a classification process to determine bare-earth points and non-ground points utilizing "first and only" as well as "last of many" LiDAR returns. This process determined Default (Class 1), Ground (Class 2),Noise (Class 7), Model Key Points (Class 8), and Overlap (Class 12) classifications. The bare-earth (Class 2 - Ground) LiDAR points underwent a manual QA/QC step to verify that artifacts have been removed from the bare-earth surface. The surveyed ground control points are used to perform the accuracy checks and statistical analysis of the LiDAR dataset.
    • The NOAA Coastal Services Center (CSC) received topographic files in LAS format. The files contained lidar elevation and intensity measurements. The data were received in NAD83 UTM18N, meters Projected Coordinates and were vertically referenced to NAVD88 using the Geoid12a model. The vertical units of the data were meters. CSC performed the following processing for data storage and Digital Coast provisioning purposes: 1. The topographic las files were converted from orthometric (NAVD88) heights to ellipsoidal heights using Geoid12a. 2. The topographic las files were converted from Projected Coordinates (Nad83 UTM18N, meters) to Geographic Coordinates (NAD83, decimal degrees). 3. The data were converted to LAZ format.
    • 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: 2013-02-20

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