Ground control point locations for UAS surveys of the beaches at Fort Stevens State Park, OR, and Cape Disappointment State Park, WA, August 2017

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Frequently anticipated questions:


What does this data set describe?

Title:
Ground control point locations for UAS surveys of the beaches at Fort Stevens State Park, OR, and Cape Disappointment State Park, WA, August 2017
Abstract:
This portion of the data release presents the locations of the temporary ground control points (GCPs) used for the structure-from-motion (SfM) processing of the imagery collected during the August 2017 unoccupied aerial system (UAS) surveys of the ocean beach at Fort Stevens State Park, OR, and Benson Beach at Cape Disappointment State Park, WA. Eighteen temporary ground control points (GCPs) were distributed throughout the survey area to establish survey control. The GCPs consisted of a combination of small square tarps with black-and-white cross patterns and "X" marks placed on the ground using temporary chalk. The GCP positions were measured using dual-frequency real-time kinematic (RTK) or post-processed kinematic (PPK) GPS with corrections referenced to a static base station operating nearby. The GCP positions are presented in a comma-delimited text file.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-666-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Logan, Joshua B., Stevens, Andrew W., and Harrison, Shawn R., 20230623, Ground control point locations for UAS surveys of the beaches at Fort Stevens State Park, OR, and Cape Disappointment State Park, WA, August 2017: data release DOI:10.5066/P9BVTVAW, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Logan, Joshua B., Stevens, Andrew W., Harrison, Shawn R., and Johnson, Cordell D., 2023, Aerial imagery and structure-from-motion data products from UAS surveys of the beaches at Fort Stevens State Park, OR, and Cape Disappointment State Park, WA: data release DOI:10.5066/P9BVTVAW, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: Logan, J.B., Stevens, A.W., Harrison, S.R., and Johnson, C.D., 2023, Aerial imagery and structure-from-motion data products from UAS surveys of the beaches at Fort Stevens State Park, OR, and Cape Disappointment State Park, WA: U.S. Geological Survey data release, https://doi.org/10.5066/P9BVTVAW.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -124.07881
    East_Bounding_Coordinate: -123.99639
    North_Bounding_Coordinate: 46.29649
    South_Bounding_Coordinate: 46.20298
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/64384d99d34ee8d4addf02a8?name=F01_20170807T163326Z_RA007716.JPG&allowOpen=True (JPEG)
    Aerial image showing example of ground control point used for the UAS surveys.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 07-Aug-2017
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  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 (68)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: State Plane Coordinate System 1983
      State_Plane_Coordinate_System:
      SPCS_Zone_Identifier: 4602
      Lambert_Conformal_Conic:
      Standard_Parallel: 47.33333
      Standard_Parallel: 45.83333
      Longitude_of_Central_Meridian: -120.50000
      Latitude_of_Projection_Origin: 45.33333
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (EPSG:4269).
      The ellipsoid used is GRS 1980 (EPSG:7019).
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name:
      North American Vertical Datum of 1988 (EPSG:5703), derived using GEOID12B
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the dataset (Source: Producer defined)
    pid
    Point ID (Source: producer defined) A unique identification code for the point.
    northing_m
    Northing coordinate of data point relative to the North American Datum of 1983, projected in Washington State Plane, South (zone 4602) coordinate system, in units of meters (EPSG:32149) (Source: Producer defined)
    Range of values
    Minimum:102644.840
    Maximum:113293.869
    Units:meters
    easting_m
    Easting coordinate of data point relative to the North American Datum of 1983, projected in Washington State Plane, South (zone 4602) coordinate system, in units of meters (EPSG:32149) (Source: Producer defined)
    Range of values
    Minimum:224161.840
    Maximum:230257.288
    Units:meters
    orthometric_ht_m
    Orthometric height of data point in meters relative to the North American Vertical Datum of 1988 (EPSG:5703), derived using the National Geodetic Survey GEOID12B. (Source: Producer defined)
    Range of values
    Minimum:0.578
    Maximum:7.025
    Units:meters
    latitude_dd
    Latitude in decimal degrees, relative to the North American Datum of 1983 (EPSG:4269). (Source: Producer defined)
    Range of values
    Minimum:46.20298168
    Maximum:46.29648156
    Units:decimal degrees
    longitude_dd
    Longitude in decimal degrees, relative to the North American Datum of 1983 (EPSG:4269). (Source: Producer defined)
    Range of values
    Minimum:-124.07881931
    Maximum:-123.99639056
    Units:decimal degrees
    ellipsoid_ht_m
    Ellipsoid height in meters, referenced to the GRS 1980 ellipsoid (EPSG:7019). (Source: Producer defined)
    Range of values
    Minimum:-23.902
    Maximum:-17.124
    Units:meters
    Entity_and_Attribute_Overview:
    The first row of the csv file is a header line. Each following row represents one ground control point.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Joshua B. Logan
    • Andrew W. Stevens
    • Shawn R. Harrison
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These data were obtained to evaluate changes in shoreline position and coastal morphology. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify topographic features on the sub-aerially exposed portions of the beaches surveyed.

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: Aug-2017 (process 1 of 1)
    Ground control was established using ground control points (GCPs) consisting of a combination of small square tarps with black-and-white cross patterns and temporary "X" marks placed with chalk on the ground surface throughout the survey area. The GCP positions were measured using either real-time kinematic (RTK) or post-processed kinematic (PPK) GPS, using corrections from GPS base stations located near the survey area. For each GCP measurement the GPS receiver was placed on a fixed-height tripod and set to occupy the GCP for a minimum occupation time of one minute. Post-processing was conducted using the Trimble Business Center software package. Person who carried out this activity:
    Joshua Logan
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

    831-460-7519 (voice)
    jlogan@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?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    GCP positions were measured using survey-grade dual-frequency GPS receivers operating in post-processed-kinematic (PPK) mode. The GPS receivers were placed on short fixed-height tripods and set to occupy each GCP for a minimum occupation time of one minute. The PPK corrections were referenced to a single GPS base station concurrently occupying a nearby benchmark with published horizontal coordinates relative to the North American Datum of 1983. The horizontal positions of the geodetic reference network meet first-order specifications established by the National Geodetic Survey with a horizontal accuracy of 2 cm or better. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GNSS rover is 0.8 cm + 1 ppm. Baselines from the GNSS base station varied between 0.8 km and 5.8 km with a mean of 2.8 km, suggesting the average horizontal accuracy of rover positions to be about 1 cm. Combining the uncertainty in the benchmark and rover yields a total uncertainty of 3 cm. Uncertainty in the horizontal positions associated with tripod centering, antenna height measurement errors, and errors from the weight of the tripod settling onto the GCP tarp during data collection, and possible subsequent rebound of the center of the tarp after removal is unknown.
  3. How accurate are the heights or depths?
    GCP positions were measured using survey-grade dual-frequency GPS receivers operating in post-processed-kinematic (PPK) mode. The GPS receivers were placed on short fixed-height tripods and set to occupy each GCP for a minimum occupation time of one minute. The PPK corrections were referenced to a single GPS base station concurrently occupying a nearby benchmark with published vertical coordinates relative to the North American Datum of 1983. The vertical positions of the geodetic reference network meet 2 cm local ellipsoid height specifications established by the National Geodetic Survey. Manufacturer reported accuracy for the differentially corrected vertical positions for the GNSS rover is 1.5 cm + 1 ppm. Baselines from the GNSS base station varied between 0.8 km and 5.8 km with a mean of 2.8 km, suggesting the average vertical accuracy of rover positions to be about 1.8 cm. Combining the uncertainty in the benchmark and rover yields a total uncertainty of 3.8 cm. Uncertainty in the vertical positions associated with tripod centering, antenna height measurement errors, and errors from the weight of the tripod settling onto the GCP tarp during data collection, and possible subsequent rebound of the center of the tarp after removal is unknown.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. 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?
    No formal logical accuracy tests were conducted.

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 USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The GCP locations are available in a comma-delimited text format.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by 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.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    The downloadable data file is available in comma-separated values (CSV) spreadsheet format. Text editing software can be used to open the file, as well as spreadsheet programs, such as Microsoft Excel.

Who wrote the metadata?

Dates:
Last modified: 23-Jun-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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