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

Alternate Views: Get Data, FAQ, ISO Rubric, DOI Rubric, CSW, HTML, Components, XML

2011 U.S. Geological Survey (USGS) Topographic LiDAR: Louisiana Region 2

browse graphicThis kmz file shows the extent of coverage for the 2011 ARRA USGS Lousiana Region 2 lidar data set.
TASK NAME: Louisiana Region 2 LiDAR ARRA Task Order LiDAR Data Acquisition and Processing Production Task- Orleans, Plaquemines, St. Bernard, St. Tammany Parishes, and Hancock County (MS) USGS Contract No: G10PC00057 Task Order No: G10PD02781 Woolpert ORDER NUMBER: 70930 CONTRACTOR: Woolpert, Inc. LiDAR data is a remotely sensed high resolution elevation data collected by an airborne platform. The LiDAR sensor uses a combination of laser range finding, GPS positioning, and inertial measurement technologies. The LiDAR systems collect data point clouds that are used to produce highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures, and vegetation. The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 2.0 meters. The final products include first, last, and at least one intermediate return LAS, full classified LAS and a bare earth model in separate files.

Cite this dataset when used as a source.

Search and Download
    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 USGS (United States Geological Survey)
    (573) 308-3654
    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
    • U.S. Geological Survey
    Publisher
    • DOC/NOAA/NOS/CSC > Coastal Services Center, National Ocean Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce
    Date(s)
    • publication: 2011-04-15
    Data Presentation Form: Digital image
    Dataset Progress Status Complete
    Data Update Frequency: As needed
    Supplemental Information: The reflective surface data represents the DEM created by the 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 interaction of the surface materials with laser energy, at the wavelength transmitted by the sensor. The bare earth model is created by identifying the returns that fall on the ground surface and by interpolating a surface between these points. In this manner, buildings and vegetation are removed from the bare earth model. This data set does not include bridges and overpasses in the bare earth model as the delineation point for these structures is not reliably discernable in the LiDAR data.
    Purpose: This task order consisted of LiDAR data acquisition and processing for Orleans, Plaquemines, St. Bernard, St. Tammany Parishes in southeastern Louisiana, and Hancock County in southwestern Mississippi. The task order area of interest encompasses approximately 7,301 square kilometers (2,819 square miles). The task required the LiDAR data to be collected at a nominal pulse spacing (NPS) of 2.0 meters. The LiDAR data was collected to meet a vertical accuracy requirement of 12.5 cm (0.41 ft) RMSE, or better. The final LiDAR data was delivered as 1,500m x 1,500m tiles, aligned to even 1,500m coordinates.
    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: 2011-01-11  to  2011-03-01
    Spatial Reference System: urn:ogc:def:crs:EPSG::4269 Ellipsoid in Meters
    Spatial Bounding Box Coordinates:
    N: 30.258269
    S: 28.901380
    E: -89.026134
    W: -90.006583
    Spatial Coverage Map:
    Themes
    • Topography/Bathymetry
    • Elevation
    • Lidar
    • LAS
    Places
    • Louisiana
    • Orleans Parish
    • Plaquemines Parish
    • St. Bernard Parish
    • St. Tammany Parish
    • Mississippi
    • Hancock 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
    • Using a LH Systems ALS50 Light Detection And Ranging (LiDAR) system, 160 flight lines of high density data, at a nominal pulse spacing (NPS) of 2.0 meters, were collected over approximately 7,301 square meters (2,819 square miles) of Orleans, Plaquemines, St. Bernard and St. Tammany Parishes in southeastern Louisiana. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of sixteen missions were flown over a 12 day period: January 11 - 14, 2011, January 21, 2011, January 29, 2011, February 11 - 15, 2011, February 21, 2011, February 28, 2001, and March 1, 2011 . A minimum of two airborne global positioning system (GPS) base stations were used in support of the LiDAR data acquisition. 22 ground control points were surveyed through static methods. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid09. All data for Region 2 is referenced to UTM 16N for the area within its zone, NAD83, 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 ArcINFO ArcGrid binary format 2m cell size: bare-earth. The ArcGrid data was created using ArcMap v93. software. System Parameters: - Type of Scanner = LH Systems ALS50 - Data Acquisition Height = 2,377-meters AGL - Scanner Field of View = 40 degrees - Scan Frequency = 36.7 Hertz - Pulse Repetition Rate = 99.0 Kilohertz - Aircraft Speed = 140 Knots - Swath Width = 1730-meters - Number of Returns Per Pulse = Maximum of 4 - Distance Between Flight Lines = 1212-meters.
    • The ALS50 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 bare-earth points (Class 2), Noise (Class 7), Water (Class 9) Ignored ground (Class 10) and unclassified data (Class 1). 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.
    • Breaklines defining lakes, greater than two acres, and double-line streams, wider than 30.5 meters (100 feet), were compiled using digital photogrammetric techniques as part of the hydrographic flattening process and provided as ESRI Polyline Z and Polygon Z shape files. Breaklines defining water bodies and streams were compiled for this task order. The breaklines were used to perform the hydrologic flattening of water bodies, and gradient hydrologic flattening of double line streams. Lakes, reservoirs and ponds, at a nominal minimum size of two (2) acres or greater, were compiled as closed polygons. The closed water bodies were collected at a constant elevation. Rivers and streams, at a nominal minimum width of 30.5 meters (100 feet), were compiled in the direction of flow with both sides of the stream maintaining an equal gradient elevation. The draping of the polygons and double lines streams was performed using proprietary software developed by Woolpert. The hydrologic flattening of the LiDAR data was performed for inclusion in the National Elevation Dataset (NED).
    • 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 UTM Zone 16 (NAD83) coordinates and were vertically referenced to NAVD88 using the Geoid09 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 Geoid09. 2. 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: 2013-01-22

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