Ground control point locations for UAS survey of the Liberty Island Conservation Bank Wildlands restoration site, Sacramento-San Joaquin Delta, California, 2018-10-23

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Frequently anticipated questions:

What does this data set describe?

Title:
Ground control point locations for UAS survey of the Liberty Island Conservation Bank Wildlands restoration site, Sacramento-San Joaquin Delta, California, 2018-10-23
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 Unmanned Aerial System (UAS) survey on of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta on 2018-10-23. The GCPs were used to establish ground control for the survey and consisted of 24 small (80 x 80 centimeter) square tarps with black-and-white cross patterns placed on the ground surface throughout the mapping area during the survey. The GCP positions were measured using RTK GPS, with corrections from a GPS base station located approximately 3 kilometers south of the study area. 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:
http://cmgds.marine.usgs.gov/fan_info.php?fan=2018-676-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., Johnson, Cordell D., and Lacy, Jessica R., 20200817, Ground control point locations for UAS survey of the Liberty Island Conservation Bank Wildlands restoration site, Sacramento-San Joaquin Delta, California, 2018-10-23: data release DOI:10.5066/P9GF8R1M, 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., Johnson, Cordell D., and Lacy, Jessica R., 2020, Aerial imagery and structure-from-motion derived data products from UAS survey of the Liberty Island Conservation Bank Wildlands restoration site, Sacramento-San Joaquin Delta, California, October 2018: data release DOI:10.5066/P9GF8R1M, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.6755
    East_Bounding_Coordinate: -121.6677
    North_Bounding_Coordinate: 38.3358
    South_Bounding_Coordinate: 38.3260
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5f24b3e582cef313ed979696?name=Wildlands_2018-10-23_GCP_browse.jpg (JPEG)
    Images of ground control targets and map of GCPs used for the UAS survey.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 23-Oct-2018
    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 (24)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      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 NAD83_National_Spatial_Reference_System_2011.
      The ellipsoid used is GRS 1980.
      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
      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 the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system (Source: Producer defined)
    Range of values
    Minimum:4242831.643
    Maximum:4243908.019
    Units:meters
    easting_m
    Easting coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system (Source: Producer defined)
    Range of values
    Minimum:615777.803
    Maximum:616450.915
    Units:meters
    orthometric_ht_m
    Orthometric height of data point in meters relative to the North American Vertical Datum of 1988, derived using the National Geodetic Survey GEOID12A. (Source: Producer defined)
    Range of values
    Minimum:1.644
    Maximum:6.340
    Units:meters

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
    • Cordell D. Johnson
    • Jessica R. Lacy
  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 collected in support of ongoing field experiments and numerical modeling by the USGS and others, with funding from the U.S. Bureau of Reclamation, to improve our understanding of habitat quality, the influence on various landscape features on ecosystem function, and the effects of restoration actions in the Sacramento–San Joaquin Delta. These data are intended for science researchers, students, policy makers, and the general public.

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: 23-Oct-2018 (process 1 of 2)
    Ground control was established using twenty-four temporary ground control points (GCPs) consisting of small (80 x 80 centimeter) square tarps with black-and-white cross patterns placed on the ground surface throughout the survey area. The GCP positions were measured using survey-grade GPS receivers operating in real-time-kinematic (RTK) 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 RTK corrections were referenced to a static GPS base station operating on a benchmark approximately 3 kilometers south of the survey area. The position of the benchmark was previously established using the average of three static GPS occupations (2017-06-26 to 2017-06-28) with durations between 4 and 8 hours, processed using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS). 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
    Date: 19-Oct-2020 (process 2 of 2)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. 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)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Fregoso, Theresa A., Stevens, Andrew W., Wang, Rueen-Fang, Handley, Thomas, Dartnell, Peter, Lacy, Jessica R., Ateljevich, Eli, and Dailey, Evan T., 2020, Bathymetry, topography, and acoustic backscatter data, and a digital elevation model (DEM) of the Cache Slough Complex and Sacramento River Deep Water Ship Channel, Sacramento-San Joaquin Delta, California: U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

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 real-time kinematic (RTK) 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 RTK corrections were referenced to a static GPS base station operating on a benchmark approximately 3 kilometers south of the survey area. The position of the benchmark was previously established using three static GPS occupations (2017-06-26 to 2017-06-28) with durations between 4 and 8 hours, processed using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS). The processed positions from each static occupation were averaged (standard deviation individual horizontal positions were less than 1 cm) to derive the final position of the benchmark. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GPS rover positions is 0.8 cm + 0.5 ppm. The maximum baseline from the GPS base stations was approximately 3 km, suggesting the minimum horizontal accuracy to be about 1 cm.
  3. How accurate are the heights or depths?
    GCP positions were measured using survey-grade dual-frequency GPS receivers operating in real-time kinematic (RTK) 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 RTK corrections were referenced to a static GPS base station operating on a benchmark approximately 3 kilometers south of the survey area. The position of the benchmark was previously established using three static GPS occupations (2017-06-26 to 2017-06-28) with durations between 4 and 8 hours, processed using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS). The processed positions from each static occupation were averaged to derive the final position of the benchmark, resulting in an estimated elevation uncertainty of 1 cm. Manufacturer reported accuracy for the differentially corrected vertical positions for the GPS rover positions is 1.5 cm + 1 ppm. The maximum baseline from the GPS base stations was approximately 3 km, suggesting the minimum vertical accuracy to be about 3 cm. Uncertainty in the vertical positions associated with the weight of the tripod settling onto the GCP tarp during data collection, and possible subsequent vertical 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: 19-Oct-2020
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)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P9GF8R1M/Wildlands_2018-10-23_GCP_metadata.faq.html>
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