National Geophysical Data Center (NGDC), NOAA Satellite and Information Service

View Metadata As: Get Data, FAQ, HTML, 19139 XML
Assess Metadata For: Completeness, DOI Readiness, CSW Readiness, Components

2007 FEMA New Jersey Flood Mitigation Lidar: Gloucester County

browse graphicThis kmz file shows the extent of coverage for the 2007 FDEM Bay County, FL lidar data set.
LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1 second GPS with 100hz inertial measurement unit corrections, Terrapoint's LIDAR instruments are able to make highly detailed geospatial elevation products of the ground, man-made structures and vegetation. These data were collected from March 29 - April 6, 2007 for Gloucester County, New Jersey. The project area covers 353 square miles. The LiDAR flightlines for this project were planned for a 50% acquisition overlap. The nominal resolution of this project without overlap is 1.25 m. Four returns were recorded for each pulse in addition to an intensity value. GPS Week Time, Intensity, Flightline and number attributes were provided for each LiDAR point. Data is provided as random points, in LAS v1.1 format, classified according to the following ASPRS Class Codes: Class 1 - Non-ground Class 2 - Ground Class 7 - Noise Class 9 - Water

Cite this dataset when used as a source.

Search and Download
    Distribution Formats
    • LAZ
    Distributor DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Point of Contact Federal Emergency Management Agency, Region II
    Associated Resources
    • Lidar QA/QC Report
    Originator
    • DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Originator
    • DHS/FEMA > Federal Emergency Management Agency, U.S. Department of Homeland Security
    Publisher
    • DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2007-11-23
    Edition: One
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: Not planned
    Supplemental Information: Please note that the LiDAR intensity is not calibrated or normalized. The intensity value is meant to provide relative signal return strengths for features imaged by the sensor. Water is not included in the bare earth ground model, rather it is classified as water on Class 9. Water body delineation was collected using hillshades, intensity and cross-sections from the LiDAR. In the event of multiple tides from overlapping missions only the lowest tide was included for the water; nor were the peaks of tall waves; all remaining points within the water body were classified to class 1.
    Purpose: The purpose of this LiDAR data was to produce high accuracy 3D elevation based geospatial products for floodplain mapping for Gloucester County, New Jersey.
    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: 2007-03-29  to  2007-04-06
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 39.888795
    S: 39.504954
    E: -74.862458
    W: -75.450650
    Spatial Coverage Map:
    Themes
    • Bathymetry/Topography
    • ASPRS standards
    • DEM
    • digital elevation model
    • elevation
    • LAS_v1.1
    • laser
    • LiDAR
    • OPTECH_3100EA
    • surface model
    Places
    • US
    • New Jersey
    • Gloucester County
    Use Constraints No constraint information available
    Fees Fee information not available.
    Lineage Statement Lineage statement not available.
    Processor
    • Terrapoint USA
    • Terrapoint USA
    • DOC/NOAA/NOS/OCM > Office for Coastal Management, 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
    • General Overview: Project Area = 874 square kilometers, Type of Scanner = Optech 3100EA, Number of Scanners = 1, Data Acquisition Height = 1550 meters, AGL Scanner Field of View = 46 degrees, The scan frequency = 30 Hertz, Pulse Repetition Rate = 71 Kilohertz, Aircraft Speed = 150 Knots, Swath Width = 1315 m, Nominal Ground Sample Distance = 1.25 meters - no overlap, Number of Returns Per Pulse = 4, Distance Between Flight Lines = 658 m, The Airborne LiDAR survey was conducted using one OPTECH 3100EA system flying at a nominal height of 1550 metres AGL, a total angular coverage of 46 degrees. Flight line spacing nominally 658 meters providing overlap of 50% on adjacent flight lines. Lines were flown in NE/SW to best optimize flying time considering the layout for the project. The aircraft used for this survey was a Piper Navajo, registration C-GPJT. This aircraft has a flight range of approximately 6 hours and was flown at an average altitude of 1550 meters above ground level (AGL). The aircraft was staged from the Millville Airport and ferried daily to the project site for flight operations. GPS Receivers: A combination of Sokkia GSR 2600 and Applanix POSAv-510 dual frequency GPS receivers were used to support the airborne operations of this survey and to establish the GPS control network. Number of Flights and Flight Lines: A total of 8 missions were flown for this project with flight time ranging approximately 15 hours under good meteorological and GPS conditions. 76 flight lines were flown over the project site to provide complete coverage. Reference Coordinate System Used Existing NGS (National Geodetic Survey) monuments were observed in a GPS control network to establish 1 new station(s): Station_ID: 128U-01128U-01 was used as primary control for the project flight missions and kinematic ground surveys. The published horizontal datum of the NGS stations is NAD83 and the vertical datum NAVD88. The following are the final coordinates of the newly established control points used in this project: Station_ID: 128U-01, West_Longitude: 75 09 04.89385, North_Latitude: 39 43 09.54246, Ellips_Elev: 14.761 m, Geoid Model Used: The Geoid03 geoid model, published by the NGS, was used to transform all ellipsoidal heights to orthometric.
    • Airborne GPS Kinematic Airborne GPS kinematic data was processed on-site using GrafNav kinematic On-The-Fly (OTF) software. Flights were flown with a minimum of 6 satellites in view (13o above the horizon) and with a PDOP of better than 3.5. Distances from base station to aircraft were kept to a maximum of 30 km, to ensure a strong OTF (On-The-Fly) solution. For all flights,the GPS data can be classified as excellent, with GPS residuals of 5 cm average but no larger than 10 cm being recorded. Generation and Calibration of laser points (raw data) The initial step of calibration is to verify availability and status of all needed GPS and Laser data against field notes and compile any data if not complete. Subsequently the mission points are output using Optech's Dashmap, initially with default values from Optech or the last mission calibrated for system. The initial point generation for each mission calibration is verified within Microstation/Terrascan for calibration errors. If a calibration error greater than specification is observed within the mission, the roll pitch and scanner scale corrections that need to be applied are calculated. The missions with the new calibration values are regenerated and validated internally once again to ensure quality. All missions are validated against the adjoining missions for relative vertical biases and collected GPS kinematic ground truthing points for absolute vertical accuracy purposes. On a project level, a coverage check is carried out to ensure no slivers are present. Data Classification and Editing The data was processed using the software TerraScan, and followed the methodology described herein. The initial step is the setup of the TerraScan project, which is done by importing client provided tile boundary index (converted to the native UTM zone for processing) encompassing the entire project areas. The 3D laser point clouds, in binary format, were imported into the TerraScan project and divided in 440 tiles in LAS 1.0 format. Once tiled, the laser points were classified using a proprietary routine in TerraScan. This routine removes any obvious outliers from the dataset following which the ground layer is extracted from the point cloud. The ground extraction process encompassed in this routine takes place by building an iterative surface model. This surface model is generated using three main parameters: building size, iteration angle and iteration distance. The initial model is based on low points being selected by a "roaming window" with the assumption that these are the ground points. The size of this roaming window is determined by the building size parameter. The low points are triangulated and the remaining points are evaluated and subsequently added to the model if they meet the iteration angle and distance constraints. This process is repeated until no additional points are added within an iteration. A second critical parameter is the maximum terrain angle constraint,which determines the maximum terrain angle allowed within the classification model. The data is then manually quality controlled with the use of hillshading, cross-sections and profiles. Any points found to be of class vegetation, building or error during the quality control process, are removed from the ground model and placed on the appropriate layer. An integrity check is also performed simultaneously to verify that ground features such as rock cuts, elevated roads and crests are present. Once data has been cleaned and complete, it is then reviewed by a supervisor via manual inspection and through the use of a hillshade mosaic of the entire project area. Deliverable Tiling Scheme All files were converted to LAS 1.1, in the specified projection and units and were delivered in the client provided tiling scheme with a total of 440 tiles.
    • The NOAA Coastal Services Center (CSC) received the files in las format. The files contained Lidar elevation and intensity measurements. The data were in New Jersey State Plane projection, and NAVD88 Geoid 03 vertical datum.CSC performed the following processing to the data to make it available within the Digital Coast: 1. The data were converted from New Jersey State Plane 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

    For questions about the information on this page, please email: mike.sutherland@noaa.gov