Coastal Topography—Long Island, New York, Post-Hurricane Irene, 30 August 2011

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Frequently anticipated questions:

What does this data set describe?

Coastal Topography—Long Island, New York, Post-Hurricane Irene, 30 August 2011
Binary point-cloud data were produced for Long Island, New York, from remotely sensed, geographically referenced elevation measurements collected by Woolpert, Inc. using an Leica ALS50-II lidar sensor flown on a Cessna 404 aircraft. These data were collected post-Hurricane Irene on August 30, 2011.
Processed data products are used by the U.S. Geological Survey (USGS) CMGP's National Assessment of Coastal Change Hazards project to quantify the vulnerability of shorelines to coastal change hazards such as severe storms, sea-level rise, and shoreline erosion and retreat. Woolpert, Inc. reports that data are provided in LAS version 1.2 and include ASPRS Class 1: Processed, but unclassified; Class 2: Bare-earth ground; Class 7: Noise.
  1. How might this data set be cited?
    U.S. Geological Survey, 20161122, Coastal Topography—Long Island, New York, Post-Hurricane Irene, 30 August 2011: U.S. Geological Survey Data Release doi:10.5066/F79021W7, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.94316578
    East_Bounding_Coordinate: -72.40736420
    North_Bounding_Coordinate: 40.88919512
    South_Bounding_Coordinate: 40.51395891
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 30-Aug-2011
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: binary point cloud
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Tile
      This is a Point data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 18
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.25722210100002.
      Altitude_Datum_Name: North American Vertical Datum of 1988 (GEOID09)
      Altitude_Resolution: 0.15
      Altitude_Distance_Units: meters
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other periods may be inaccurate because of inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.
  3. To whom should users address questions about the data?
    Xan Fredericks
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    Cartographer/Lidar Coordinator
    600 4th Street South
    St. Petersburg, FL

    727 502-8086 (voice)
    727 502-8182 (FAX)
    Hours_of_Service: M-F, 8:00-4:00 ET

Why was the data set created?

The purpose of this project was to produce a highly detailed and accurate digital elevation map for Long Island, New York, for use as a management tool and to make these data available to natural-resource managers and research scientists. To ensure that SPCMSC data management protocols were followed, this survey was retroactively assigned a USGS field activity number (FAN), 11CNT04. Additional survey and data details are available at USGS Contract: G10PC00057 Task Order Number: G11PD01476

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 01-Sep-2011 (process 1 of 3)
    Woolpert, Inc. reports that 15 flight lines of high density data, at a nominal pulse spacing (NPS) of 1.0 meter, was collected over 120 kilometers of coastline (1 km swath width) along the southern shore of Long Island, New York using a Leica ALS50-II lidar sensor. Multiple returns were recorded for each laser pulse along with an intensity value for each return. A total of one (1) mission was flown on August 30, 2011. A minimum of one airborne global positioning system (GPS) base station was used in support of the LiDAR data acquisition. 11 ground control points were surveyed through static methods. The geoid used to reduce satellite derived elevations to orthometric heights was Geoid09. All data for the task order is referenced to UTM 18N, 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 were delivered in the ArcINFO ArcGrid binary format: bare-earth. System Parameters: - Type of Scanner = LH Systems ALS50 - Data Acquisition Height = 1,981 meters (6,500 feet) AGL - Scanner Field of View = 40 degrees - Scan Frequency = 41.8 Hertz - Pulse Repetition Rate - 115.6 Kilohertz - Aircraft Speed = 130 Knots - Swath Width = 1,442 meters (4,732 feet) - Number of Returns Per Pulse = Maximum of 4 - Distance Between Flight Lines = 1,010 meters (3,313 feet). 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), 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. Person who carried out this activity:
    Woolpert, Inc.
    4454 Idea Center Blvd.
    Dayton, OH

    (937) 461-5660 (voice)
    (937) 461-0743 (FAX)
    Hours_of_Service: Monday through Friday 8:00 AM to 5:00 PM (Eastern Time)
    Data sources produced in this process:
    • Classified LAS
    Date: 24-Jan-2017 (process 2 of 3)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    Date: 13-Oct-2020 (process 3 of 3)
    Added keywords section with USGS persistent identifier as theme keyword. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Woolpert, Inc. reports that the LiDAR collected for this task order was collected at a vertical accuracy of 18.0 cm (0.59 ft) Root Mean Squared (RMSE), or better, so that when combined with breaklines, it will adequately support the generation of two (2) foot FEMA compliant contours.
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
    Woolpert, Inc. reports that the LiDAR data vertical accuracy RMSE is 4.8 cm (0.16 ft) and that the data collected under this Task Order meets the National Standard for Spatial Database Accuracy (NSSDA) accuracy standards. The NSSDA standards specify that vertical accuracy be reported at the 95 percent confidence level for data tested by an independent source of higher accuracy. ( The Fundamental Vertical Accuracy (FVA) of the TIN: 9.4 cm (0.31 ft) at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 18.0 cm in the "open terrain" land cover category.
  4. Where are the gaps in the data? What is missing?
    Woolpert, Inc. reports that all deliverables meet specifications in contract and that the LAS Files meet ASPRS and USGS Classification Standards at the time of data delivery, including ASPRS classes 1, 2, and 7.
  5. How consistent are the relationships among the observations, including topology?
    Woolpert, Inc. reports that all formatted data were validated using commercial GIS software to ensure proper formatting and loading prior to delivery.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Xan Fredericks
    Cartographer/Lidar Coordinator
    600 4th Street South
    St. Petersburg, FL

    727 502-8086 (voice)
    Hours_of_Service: M-F, 8:00-4:00 ET
  2. What's the catalog number I need to order this data set? LINY2011_HRIR_BE_z18_n88g09_classified.laz
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. Is there some other way to get the data?
    Contact U.S. Geological Survey for details.

Who wrote the metadata?

Last modified: 13-Oct-2020
Metadata author:
Xan Fredericks
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Cartographer/Lidar Coordinator
600 4th Street South
St. Petersburg, FL

727 502-8086 (voice)
Hours_of_Service: M-F, 8:00-4:00 ET
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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