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

2004 Connecticut Lidar

LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning and inertial measurement technologies; LIDAR instruments are able to make highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures and vegetation. This data was collected at submeter resolution to provide nominal 1m spacing of collected points. Two returns were recorded for each pulse in addition to an intensity value. This data set is a raster file of z values with 153 columns and 61 rows. The data set was generated from a larger data set and includes all valid points within the requested geographic bounds.

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 DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    843-740-1200
    coastal.info@noaa.gov
    Associated Resources
    • Lidar Final Report
    Originator
    • DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    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: 2006-08-14
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: Not planned
    Supplemental Information: Reflective surface data represents the DEM created by laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface to be reflected by a subsequent surface as represented by the Last Return data. Intensity information is captured from the Reflective Surface pulse and indicates the relative energy returned to the sensor as compared to the energy transmitted. The Intensity image is not calibrated or normalized but indicates differences in energy absorption due to the the interaction of the surface materials with laser energy at the wavelength transmitted by the sensor. Points are classified as on ground surface or not on ground surface to support creation of a bare earth model from the data. Open water is classified as not bare ground.
    Purpose: LIDAR data is used for 3D visualization, elevation based analysis and for feature extraction.
    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: Unknown  to  Unknown
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 41.453890
    S: 41.240042
    E: -72.279933
    W: -72.908092
    Spatial Coverage Map:
    Themes
    • Bathymetry/Topography
    • elevation
    • lidar
    • laser
    • beach
    • topography
    • digital elevation model
    • DEM
    • erosion
    Places
    • United States
    • Connecticut
    • New Haven
    • Old Saybrook
    • Qunnipiac River
    • New Haven Harbor
    • Connecticut Coastline
    • Connecticut River
    Use Constraints No constraint information available
    Fees Fee information not available.
    Source Datasets
    • Collection System Calibration
      • Description of Source: Source Contribution: System Calibration. Minimizes horizontal error caused by IMU mis-alignment by checking over known range and by comparing positional results from adjacent flight lines to compute error adjustment function. Source Type: Validation Report
      • Temporal extent used:  unknown  to 
    Lineage Statement Lineage statement not available.
    Processor
    • 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
    • Data Collection: Using a LH Systems ALS50 Light Detection And Ranging (LiDAR) system, 41 flight lines of high density (submeter ground sample distance) data were collected over areas in coastal Connecticut (approximately 300 square kilometers). Two returns were recorded for each laser pulse along with an intensity value for each return. The data acquisition occurred in one (1) mission on October 8, 2004. Three (3) airborne global positioning system (GPS) base stations were used to support the LiDAR data acquisition: Moriches 1 continuously operating reference station (CORS) ARP, NGS point P36, and one station Woolpert located using static GPS positioning methods, Madison CP. In addition, twenty-two control points were surveyed through fast-static GPS methods to support the final accuracy analysis and tied into the National Geodetic Survey (NGS) points Moriches CORS and P36.
    • Airborne GPS Processing: 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 overlap between flight lines was removed to provide a homogeneous coverage, and the coverage was classified to extract a bare earth digital elevation model (DEM). Airborne GPS is differentially processed using the GrafNAV V4.10 software by Waypoint Consulting of Calgary, Alberta, Canada. The PDOP and distance separation is as follows: P36: Maximum PDOP = 3.58 (maximum) Average Distance Separation: 17 km Madison CP: Maximum PDOP = 3.58 (maximum) Average Distance Separation: 19 km IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada. The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia. The classification and quality control (QC) of LiDAR data is carried out using a combination of proprietary software and TerraScan software by Terrasolid Limited of Helinski, Finland. Two (2) coverages were delivered in the LAS file format: bare-earth and above ground features.
    • IMU data Processing: IMU data provides information concerning roll, pitch and yaw of collection platform during collection event. IMU information allows the pulse vector to be properly placed in 3D space allowing the distance from the aircraft reference point to be properly positioned on the elevation model surface. IMU data is processed using the PosPac V4.2 software by Applanix Corporation of Richmond Hill, Ontario, Canada.
    • Reflective Surface Generation: The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia.
    • LIDAR Point Classification The classification and quality control (QC) of LiDAR data is carried out using a combination of proprietary software and TerraScan software by Terrasolid Limited of Helinski, Finland.
    • Output LAS Files Random LIDAR points maintained in UTM coordinate system converted to Geographic projection with units of Decimal Degrees
    • The NOAA Coastal Services Center (CSC) received files in LAS format. The files contained LiDAR intensity and elevation measurements. CSC performed the following processing on the data to make it available within the LiDAR Data Retrieval Tool (LDART): 1. The las files were converted from State Plane coordinates to Geographic coordinates. 2. The las header fields were sorted by latitude and updated. 3. The data were converted from orthometric to ellipsoidal heights using Geoid03.
    • 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: 2013-05-07

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