Terrestrial-Based Lidar Beach Topography of Fire Island, New York, June 2014

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Frequently anticipated questions:


What does this data set describe?

Title:
Terrestrial-Based Lidar Beach Topography of Fire Island, New York, June 2014
Abstract:
The U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) in Florida and the USGS Lower Mississippi-Gulf Water Science Center (LMG WSC) in Montgomery, Alabama, collaborated to gather alongshore terrestrial-based lidar beach elevation data at Fire Island, New York. This high-resolution elevation dataset was collected on June 11, 2014, to characterize beach topography and document ongoing beach evolution and recovery, and is part of the ongoing beach monitoring within the Hurricane Sandy Supplemental Project GS2-2B. This USGS data series includes the resulting processed elevation point data (xyz) and an interpolated digital elevation model (DEM).
  1. How might this data set be cited?
    U.S. Geological Survey St. Petersburg Coastal and Marine Science Center, 2016, Terrestrial-Based Lidar Beach Topography of Fire Island, New York, June 2014: U.S. Geological Survey Data Series DS 980, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

    This is part of the following larger work.

    Brenner, Owen, Hapke, Cheryl J., Lee, Kathryn G., and Kimbrow, Dustin R., 2016, Terrestrial-based lidar beach topography of Fire Island, New York, June 2014: U.S. Geological Survey Data Series DS 980, U.S. Geological Survey St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -73.205753312
    East_Bounding_Coordinate: -72.831031025
    North_Bounding_Coordinate: 40.749777289
    South_Bounding_Coordinate: 40.625667641
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 11-Apr-2013
    Currentness_Reference:
    ground elevation
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Tabular digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a point data set. It contains the following vector data types (SDTS terminology):
      • Point (21,492,789)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 18
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum 1983.
      The ellipsoid used is Geodectic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum 1988
      Altitude_Resolution: 0.0001 cm
      Altitude_Distance_Units: meter
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    20140611_FI_USGS_XYZ.txt
    Comma delimited xyz (Source: U.S. Geological Survey)
    FID
    Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated.
    POINT_X
    UTM x-axis coordinate (Zone 18N) (Source: U.S. Geologocial Survey)
    Range of values
    Minimum:-73.205753312
    Maximum:-72.831031025
    Units:Meter
    POINT_Y
    UTM y-axis coordinate (Zone 18N) (Source: U.S. Geological Survey)
    Range of values
    Minimum:40.749777289
    Maximum:40.625667641
    Units:Meter
    POINT_Z
    z- value (Source: U.S. Geological Survey)
    Range of values
    Minimum:-3.7017
    Maximum:14.5137
    Units:meters
    Entity_and_Attribute_Overview:
    Comma delimited xyz file containing FID, UTM X, UTM Y locations and corresponding Z elevation value, all in meters.
    Entity_and_Attribute_Detail_Citation:
    Beach topography point data for Fire Island, New York, which was created from data collected during a ground-based lidar survey on June 11, 2014.

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 St. Petersburg Coastal and Marine Science Center
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Owen Brenner
    600 4th Street South
    St Petersburg, FL
    USA

    727-502-8085 (voice)
    727-502-8001 (FAX)
    obrenner@usgs.gov

Why was the data set created?

To collect, process, and disseminate beach topography data collected along 30 kilometers (km) of Fire Island, New York, from the western boundary of Fire Island National Seashore to the Wilderness Breach.

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: 2014 (process 1 of 5)
    Pre-Survey Calibration: The mobile T-lidar system requires a rigorous calibration procedure before accurate datasets can be generated. All instrumentation must first be surveyed, and their relative positions (lever arms) must be resolved with respect to the origin point of the IMU. Next, a boresight procedure is performed in order to determine the angular differences (that is, roll, pitch, and heading) between the IMU and the T-lidar instrument. Person who carried out this activity:
    USGS Lower Mississippi-Gulf Water Science Center (LMG WSC)
    Attn: Katie G. Lee
    Hydraulic Engineer
    USGS Alabama Water Science Center
    Montgomery, AL
    USA

    334-395-4120 (voice)
    334-395-4168 (FAX)
    kmlee@usgs.gov
    Contact_Instructions: http://al.water.usgs.gov/
    Date: 2014 (process 2 of 5)
    SBET and Point Cloud Creation: The POSMV system collected attitude and trajectory information during the survey, and these data were later post-processed using Applanix POSPac MMS (2013) software with GPS data, collected at a nearby benchmark. The POSPac MMS software uses differential correction algorithms to compute a smoothed best estimate of trajectory (SBET) file and associated positional accuracy report of the processed SBET. The SBET file is then applied to the raw T-lidar data along with the boresight parameter file using Optech Parser software to produce a geo-referenced point-cloud dataset. Person who carried out this activity:
    USGS Lower Mississippi-Gulf Water Science Center (LMG WSC)
    Attn: Katie G. Lee
    Hydraulic Engineer
    USGS Alabama Water Science Center
    Montgomery, AL
    USA

    334-395-4120 (voice)
    334-395-4168 (FAX)
    kmlee@usgs.gov
    Contact_Instructions: http://al.water.usgs.gov/
    Date: 2014 (process 3 of 5)
    Using Innovmetric Polyworks software, the point clouds were filtered using several methods: (1) intensity, (2) height above a digital elevation model (DEM) surface, and (3) visual inspection. A preliminary DEM surface was created using a 0.25-meter (m) grid, and points that were 0.1 m higher than the generated surface were removed. Vegetation was removed by selecting points above a DEM surface. Each point within the point cloud has an intensity value (ranges from 0 to 255) associated with it that represents the amount of near-infrared reflectance received by the T-lidar instrument. The points with relatively low intensity values were examined and removed, if necessary. Once the data were filtered, an updated DEM surface was generated and manually edited to remove any remaining outliers. Additionally, the data were edited to smooth out any differences caused by temporal data collection. The final xyz point-cloud data are then created at 1-m horizontal resolution (fig. 2). Person who carried out this activity:
    USGS Lower Mississippi-Gulf Water Science Center (LMG WSC)
    Attn: Katie G. Lee
    Hydraulic Engineer
    USGS Alabama Water Science Center
    Montgomery, AL
    USA

    334-395-4120 (voice)
    334-395-4168 (FAX)
    kmlee@usgs.gov
    Contact_Instructions: http://al.water.usgs.gov/
    Date: 2014 (process 4 of 5)
    Within Esri’s ArcCatalog, the ASCII xyz point cloud file was converted to an ArcGIS multipoint feature using the ASCII 3D To Feature Class tool. Using the Feature Class Z To ASCII tool the point data was reverted back to ASCII xyz format for publication, in a non-proprietary format and projected in Universal Transverse Mercator (UTM) Zone 18N (meters). Person who carried out this activity:
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Attn: Owen Brenner
    Geologist
    600 4th Street South
    St. Petersburg, FL
    U.S.

    727-502-8085 (voice)
    727-502-8001 (FAX)
    obrenner@usgs.gov
    Date: 24-Jan-2017 (process 5 of 5)
    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?
    The errors associated with the collection of elevation data can be classified as systematic or random. Systematic errors are those that can be measured or modeled through calibration (Byrnes and others, 2002). Random errors are a result of the limitations of the measuring device and an inability to perfectly model the systematic errors. The POSPac MMS software also creates a positional accuracy file which is compared to 38 control points occupied prior to the T-lidar survey using a real-time kinematic global positioning system (RTK-GPS) unit to evaluate the accuracy of the post-processed SBET solution. The horizontal accuracy of the post-processed file has a minimum and maximum root mean square error (RMSE) of 0.4 and 1.2 centimeters (cm), respectively. The RMSE of the vertical accuracy ranged from 0.7 to 1.8 cm. Stated accuracies are based on peak-to-peak errors.
  2. How accurate are the geographic locations?
    The horizontal accuracy of the post-processed file has a minimum and maximum root mean square error (RMSE) of 0.4 and 1.2 cm, respectively.
  3. How accurate are the heights or depths?
    The RMSE of the vertical accuracy ranged from 0.7 to 1.8 cm. Stated accuracies are based on peak-to-peak errors.
  4. Where are the gaps in the data? What is missing?
    This dataset is considered complete for the information presented, as described in the abstract section. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Beach morphology data of Fire Island, New York were collected by USGS Lower Mississippi-Gulf Water Science Center (LMG WSC) using a truck-mounted mobile T-lidar. The T-lidar instrument was mounted on top of a truck, and covered 35 km of Fire Island beach at speeds of less than 16 km per hour. Data were collected June 11, 2014. This system is composed of an Optech ILRIS HD-ER-MC high frequency laser scanner in conjunction with an Applanix POSMV inertial measurement unit (IMU). A global positioning system (GPS) base station was set up on a nearby benchmark and logged vertical and horizontal position information during the survey for post-processing. During post-processing, the POSPac MMS software uses differential correction algorithms to compute a smoothed best estimate of trajectory (SBET) file. The SBET file is then applied to the raw T-lidar data along with the boresight parameter file using Optech Parser software to produce a geo-referenced point-cloud dataset. Thirty-eight additional topographic data points were collected for survey control using a real-time kinematic global positioning system (RTK-GPS) unit, which was used to assess system accuracy and variability. Point Cloud data is filtered and edited within Innovmetric Polyworks software to remove vegetation and any problematic or outlier point values.

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey, St Petersburg Coastal and Marine Science Center, as the originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, St Petersburg Coastal and Marine Science Center, St. Petersburg, FL
    Attn: Owen Brenner
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8085 (voice)
    727-502-8001 (FAX)
  2. What's the catalog number I need to order this data set? U.S. Geological Survey DS 980
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm 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: ASCII (version 9.20) Zip file containing space delimited xyz point elevation file Size: 86.9
      Network links: http://dx.doi.org/10.3133/ds980
    • Cost to order the data: None


Who wrote the metadata?

Dates:
Last modified: 24-Jan-2017
Metadata author:
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
Attn: Owen Brenner
Geologist
600 4th Street South
St. Petersburg, Florida
U.S.

727-502-8085 (voice)
727-502-8001 (FAX)
obrenner@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/DS980_20140611_FI_USGS_XYZ_metadata.faq.html>
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