EAARL-B Coastal Topography—Fire Island, New York, pre-Hurricane Sandy, 2012: Seamless (Bare Earth and Submerged)

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Frequently anticipated questions:


What does this data set describe?

Title:
EAARL-B Coastal Topography—Fire Island, New York, pre-Hurricane Sandy, 2012: Seamless (Bare Earth and Submerged)
Abstract:
This shapefile was produced from 53 2-kilometer by 2-kilometer tile extents of remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey. Elevation measurements were collected over the area using the second-generation Experimental Advanced Airborne Research Lidar, a pulsed laser ranging system mounted onboard an aircraft to measure ground elevation, vegetation canopy, and coastal topography. The system uses high-frequency laser beams directed at the Earth's surface through an opening in the bottom of the aircraft's fuselage. The laser system records the time difference between emission of the laser beam and the reception of the reflected laser signal in the aircraft. The plane travels over the target area at approximately 55 meters per second at an elevation of approximately 300 meters, resulting in a laser swath of approximately 240 meters with an average point spacing of 0.5–1.6 meters. The nominal vertical elevation accuracy expressed as the root mean square error (RMSE) is 5.24 centimeters for the bare earth topography. Additional data were insufficient to calculate an RMSE for the submerged topography. A peak sampling rate of 15–30 kilohertz results in an extremely dense spatial elevation dataset. More than 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development.
Supplemental_Information:
Raw lidar data are not in a format that is generally usable by natural-resource managers and research scientists for scientific analysis. Converting dense lidar elevation data into a readily usable format without loss of essential information requires specialized processing. The U.S. Geological Survey's Coastal and Marine Geology Program (CMGP) has developed custom software to convert raw lidar data into a GIS-compatible map product to be provided to GIS specialists, managers, and scientists. The primary tool used in the conversion process is Airborne Lidar Processing System (ALPS), a multitiered processing system developed originally by a USGS-NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL-B to georeferenced spot (x,y,z) returns for "first surface" and "bare earth" topography. The terms first surface and bare earth refer to the digital elevation data of the terrain, but although first-surface data include vegetation, buildings, and other manmade structures, bare-earth data do not. The zero crossing of the second derivative (that is, detection of stationary points) is used to detect the first return, resulting in "first surface" topography, whereas the trailing edge algorithm (that is, the algorithm searches for the location before the last return where direction changes along the trailing edge) is used to detect the range to the last return, or "bare earth" (the first and last returns being the first and last significant measurable part of the return pulse). Statistical filtering, known as the Random Consensus Filter (RCF), is used to remove false bottom returns and other outliers from the EAARL-B topography data. The filter uses a grid of non-overlapping square cells (buffer) of user-defined size overlaid onto the original point cloud. The user also defines the vertical tolerance (vertical width) based on the topographic complexity and point-sampling density of the data. The maximum allowable elevation range within a cell is established by this vertical tolerance. An iterative process searches for the maximum concentration of points within the vertical tolerance and removes those points outside of the tolerance (Nayegandhi and others, 2009). These data are then converted to the North American Datum of 1983 and the North American Vertical Datum of 1988 (using the GEOID12A model).
The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMGP's Lidar for Science and Resource Management project. Processed data products are used by the U.S. Geological Survey 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.
  1. How might this data set be cited?
    U.S. Geological Survey, 2014, EAARL-B Coastal Topography—Fire Island, New York, pre-Hurricane Sandy, 2012: Seamless (Bare Earth and Submerged): U.S. Geological Survey Data Series 888, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -28.62010867
    East_Bounding_Coordinate: -27.37834358
    North_Bounding_Coordinate: 64.51348849
    South_Bounding_Coordinate: 64.91558570
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 27-Oct-2012
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (53)
    2. What coordinate system is used to represent geographic features?
      The horizontal datum used is D_NORTH_AMERICAN_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.
  7. How does the data set describe geographic features?
    PRSF_tile_extents
    Shapefile. (Source: Esri)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    TILE_NAME
    Tile name described by UTM Zone 18 easting and northing values (in meters). (Source: U.S. Geological Survey LSRM) The first 3 numbers in the tile name attribute represent the left-most UTM east bounding coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM north bounding coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, t_e123_n4567_18).
    TILE_NUMBE
    Sequential unique whole number assigned to tiles (west-to-east, north-to-south) for identification. (Source: U.S. Geological Survey LSRM)
    Range of values
    Minimum:1
    Maximum:53
    LABEL_POS
    Spatial coordinates used to center display labels within tiles. (Source: U.S. Geological Survey LSRM) UTM Zone 18 easting (X) and northing (Y) coordinates (in meters) used to center display labels within tiles.
    Entity_and_Attribute_Overview:
    The shapefile includes sequential tile number labels, tile names, and label position coordinates.
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/2009/1078/

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
    Lidar Validation and Processing Analyst
    600 4th Street South
    St. Petersburg, FL
    USA

    727 502-8086 (voice)
    727 502-8182 (FAX)
    afredericks@usgs.gov
    Hours_of_Service: M-F, 8:00-4:00 ET

Why was the data set created?

The purpose of this project was to produce highly detailed and accurate seamless digital elevation maps for part of Fire Island, New York, pre-Hurricane Sandy (October 2012 hurricane), for use as a management tool and to make these data available to natural-resource managers and research scientists.

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-Apr-2014 (process 1 of 3)
    EAARL data were split into 2-kilometer by 2-kilometer tiles using ALPS, or the Airborne Lidar Processing System (20121105) and these extents were exported to an .xyz file (20140401). Person who carried out this activity:
    Melanie Masessa
    Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    GIS Analyst
    600 4th Street South
    St. Petersburg, FL
    USA

    727 502-8096 (voice)
    mmasessa@usgs.gov
    Hours_of_Service: M-F, 8:00-4:00 ET
    Date: 01-Apr-2014 (process 2 of 3)
    The shapefile was created from the .xyz file using Global Mapper 14 by exporting vector areas to shapefile format. Person who carried out this activity:
    Melanie Masessa
    Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    GIS Analyst
    600 4th Street South
    St. Petersburg, FL
    USA

    727 502-8096 (voice)
    mmasessa@usgs.gov
    Hours_of_Service: M-F, 8:00-4:00 ET
    Date: 24-Jan-2017 (process 3 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)
    aallwardt@usgs.gov
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This shapefile completely encompasses the provided lidar data.
  5. How consistent are the relationships among the observations, including topology?
    This shapefile represents the boundaries of the 2-kilometer by 2-kilometer tiles into which the data were split where the upper-left bound can be ascertained quickly through the tile name attribute. The first 3 numbers in the tile name represent the left-most UTM east bounding coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM north bounding coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, t_e123_n4567_18). These 2-kilometer by 2-kilometer tile extents were used to create this shapefile.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
The U.S. Geological Survey requests to be acknowledged as the originator of this file in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Xan Fredericks
    Lidar Validation and Processing Analyst
    600 4th Street South
    St. Petersburg, FL
    USA

    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? DS 888
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey (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 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?
    • Availability in digital form:
      Data format: shapefile
      Network links: http://dx.doi.org/10.3133/ds888
    • Cost to order the data: None

    • Special instructions:
      Contact U.S. Geological Survey
    • How long will it take to get the data?
      Vary

Who wrote the metadata?

Dates:
Last modified: 24-Jan-2017
Metadata author:
Melanie Masessa
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
GIS Analyst
600 4th Street South
St. Petersburg, FL
USA

727 502-8096 (voice)
mmasessa@usgs.gov
Hours_of_Service: M-F, 8:00-4:00 ET
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS888_PRSF_tile_extents.faq.html>
Generated by mp version 2.9.49 on Mon Sep 10 17:44:25 2018