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2006 FEMA New Jersey Flood Mitigation Lidar: Middlesex County

browse graphicThis kmz file shows the extent of coverage for the 2006 FEMA Middlesex County, NJ 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. The LiDAR flightlines for this project were planned for a 50% acquisition overlap. The nominal resolution of this project without overlap is 1.37m spacing, but effectively is 2.74m with overlap factored. Four returns were recorded for each pulse in addition to an intensity value. GPS Week Time, Flightline number and scan angle attributes were provided for each LiDAR point. Data is provided as random points, in LAS v1.0 format, classified according to ASPRS Class Code 1= Undefined, 2=Ground.
Cite this dataset when used as a source.
Other Access Online access information not available.
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
Dataset Point of Contact Federal Emergency Management Agency, Region II
Documentation links not available.
  • publication: 2006-11-15
Edition: One
Data Presentation Form: Digital image
Dataset Progress Status Complete
Data Update Frequency: Not planned
Supplemental Information:
Type Of Scanner = Optech 3100EA Data Acquisition Height = 1550 meters AGL Scanner Field Of View = 40 degrees Scan Frequency = 32.9 Hertz Pulse Repetition Rate = 71 Kilohertz Aircraft Speed = 180 Knots Swath Width = 1128 m Nominal Ground Sample Distance = 1.37 meters (no overlap) Number of Returns Per Pulse = 4 (first, last, intermediate) Distance Between Flight Lines = 564 Format: LAS 1.0 ASPRS Class Code 1=Undefined, 2=Ground First of many pulse and intermediate returns were not considered in the bare earth ground. 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.
Purpose: The purpose of this LiDAR data is to produce high accuracy 3D elevation based geospatial products for Middlesex 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.
  • While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by any errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.
  • DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
  • DHS/FEMA > Federal Emergency Management Agency, U.S. Department of Homeland Security
  • DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
Time Period: 2006-10-08 to 2006-10-11
Spatial Reference System: urn:ogc:def:crs:EPSG::4269
Spatial Bounding Box Coordinates:
N: 40.610366
S: 40.249866
E: -74.201558
W: -74.632358
Spatial Coverage Map:
Theme keywords None
  • Bathymetry/Topography
  • ASPRS standards
  • DEM
  • digital elevation model
  • elevation
  • LAS_v1.0
  • laser
  • LiDAR
  • OPTECH_3100EA
  • surface model
Place keywords None
  • US
  • New Jersey
  • Middlesex County
Use Constraints No constraint information available
Fees Fee information not available.
Lineage information for: dataset
  • 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
  • 2006-10-01T00:00:00 - -General Overview: The Airborne LiDAR survey was conducted using an OPTECH 3100EA flying at a nominal height of 1550 meters AGL with a total angular coverage of 40 degrees. Flight line spacing was nominally 564 meters, providing overlap of 50% on adjacent flight lines. All of the lines were flown in a north/south direction for the project. -Aircraft A Piper Navajo, registration C-GPJT, was used for the survey. This aircraft has a flight range of approximately 4.5 hours and was flown at an average altitude of 1550 meters AGL (Above Ground Level), thereby encountering flying altitudes of approximately 1550 meters above Mean Sea Level (MSL). The aircraft was staged from the Linden, NJ Airport, and ferried daily to the project site for flight operations. -GPS Receivers A combination of Sokkia GSR 2600 and NovAtel DL-4+ 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 4 missions were flown for this project with flight times ranging approximately 16.25 hours under good meteorological and GPS conditions. 55 flight lines were flown over the project area to provide complete coverage. Lines were flown at 564 meter spacing to achieve 50% lateral overlap.
  • 2006-11-01T00:00:00 - -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 (13 degrees above the horizon) and with a PDOP of better than 4.5. Distances from base station to aircraft were kept to a maximum of 35 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 8 cm being recorded. -Calculation of 3D laser points (raw data) The post-processing software o derive X,Y,Z values from roll, pitch, yaw and range is Optech's Realm. -Classification and Editing The data was processed using the software TerraScan, and following the methodology described herein. The initial step is the setup of the TerraScan project, which is done by importing client provided tile boundary index encompassing the entire project areas. The 3D laser point clouds, in binary format, were imported into the TerraScan project and divided in 425 tiles, as per the contract specifications. 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 is 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 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. -Projection Transformation The data was processed in the native UTM zone in meters and then transformed to the New Jersey State Plane final projection system and US survey feet using an in-house transformation software which utilizes Corpscon DLL.
  • 2010-09-25T00:00:00 - 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 New Jersey State Plane (NAD83) coordinates, and referenced to the orthometric datum NAVD88 using Geoid 03. 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 (NAD83) 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.
  • 2011-05-13T00:00:00 - 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.
Last Modified: 2013-06-11
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