Ground control and transect points collected during unmanned aerial systems (UAS) flights: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018

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Frequently anticipated questions:

What does this data set describe?

Title:
Ground control and transect points collected during unmanned aerial systems (UAS) flights: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018
Abstract:
Low-altitude (80 and 100 meters above ground level) digital images were taken over an area of the Plum Island Estuary and Parker River National Wildlife Refuge (NWR) in Massachusetts using 3DR Solo unmanned aircraft systems (UAS) on February 27, 2018. These images were collected as part of an effort to document marsh stability over time and quantify sediment movement using UAS technology. Each UAS was equipped with either a Ricoh GRII digital camera for natural color photos, used to produce digital elevation models and ortho images, or a MicaSense RedEdge multi-spectral camera that captures five specific bands of the visible spectrum (blue, green, red, red edge, and near-infrared), which can be used to classify vegetation. The MicaSense camera covered a smaller subsection of the same polygonal area of the marsh that the Ricoh imaged. Some photographs contain black and white targets used as ground control points (GCPs), which were surveyed by a field crew with a high-precision Real Time Kinematic Global Position System. This data release includes the original images from both cameras, as well as a csv file containing the latitude and longitude coordinates, in Universal Transverse Mercator Zone 19 referenced to the North American Datum of 1983, of the ground control points needed to complete any photogrammetry projects using the original photographs, and GPS transect points used to evaluate the photogrammetry products created.
Supplemental_Information:
These data were collected by the USGS Coastal/Marine Hazards and Resources Program under USGS field activity number 2018-015-FA. The field activity webpage (https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-015-FA) contains additional information regarding the field activity.
  1. How might this data set be cited?
    U.S. Geological Survey, 2019, Ground control and transect points collected during unmanned aerial systems (UAS) flights: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018: data release DOI:10.5066/P9O9NSRK, U.S. Geological Survey, Coastal/Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Ganju, Neil K., Brosnahan, Sandra M., Sturdivant, Emily J., Pendleton, Elizabeth A., and Ackerman, Seth D., 2018, Aerial imagery from unmanned aerial systems (UAS) flights and ground control points: Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018: data release DOI:10.5066/P9O9NSRK, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Ganju, N.K., Brosnahan, S.M., Sturdivant, E.J., Pendleton, E.A., and Ackerman, S.D., 2019, Aerial imagery from unmanned aerial systems (UAS) flights—Plum Island Estuary and Parker River NWR (PIEPR), February 27th, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9O9NSRK.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.821671
    East_Bounding_Coordinate: -70.805726
    North_Bounding_Coordinate: 42.777831
    South_Bounding_Coordinate: 42.769101
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5c98d30ce4b0b8a7f6288b7c?name=2018015FA_gcptrans_browse.jpg (JPEG)
    Browse graphic showing the locations of the ground control points and the transect points.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 27-Feb-2018
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: digital text files
  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 (81)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Universal Transverse Mercator.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -75.00000
      Latitude_of_Projection_Origin: 0.000
      False_Easting: 500000.0000
      False_Northing: 0.0000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (2011).
      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 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988 (NAVD88)
      Altitude_Resolution: 0.0001
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    2018015FA_PlumIsland_GCP.csv
    Target points and transect points collected using surveying techniques. These points are used in post-processing to improve the quality of the positioning in the final photogrammetric products (ground control points) and it assessing the vertical accuracy of the final products (transects) (Source: U.S. Geological Survey)
    ORIGINAL_ID
    Provides the unique name for each target or the transect identifier to which the point belongs. Transects consists of several records - and in this case the only transect has the unique identifier ROAD. (Source: U.S. Geological Survey) character set
    Northing
    Northing coordinate in UTM Zone 19 meters, NAD83 (2011) (Source: U.S. Geological Survey)
    Range of values
    Minimum:4736783.095
    Maximum:4737725.293
    Units:meters
    Easting
    Easting coordinate in UTM Zone 19 meters, NAD83 (2011) (Source: U.S. Geological Survey)
    Range of values
    Minimum:350982.1411
    Maximum:352266.9748
    Units:meters
    Elevation
    Orthometric elevation relative to NAVD88 (geoid12b) (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.3501
    Maximum:2.7804
    Units:meters
    DATE_Collected
    Date of point collection in mm/dd/yy format (Source: U.S. Geological Survey) character set to represent calendar date of collection
    Description
    simple descriptor used to distinguish between ground control points (Target) and transect points (TRANS) (Source: U.S. Geological Survey) character set
    Entity_and_Attribute_Overview:
    The text file 2018015FA_PlumIsland_GCP.csv lists the locations of all ground control points and transect points. The text contains one header record, and data records with six columns of comma-separated values defined by the attribute labels. The columns contain, in order, the name, northing, easting, elevation, date collected, and whether it's a target or transect. The target names (ORIGINAL_ID) are uniquely named (e.g T20, H351); the transect (consisting of several GPS fixes along a survey line) has a unique name (ROAD).
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2018-015-FA

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?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Sandra Brosnahan
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, Massachusetts

    508-548-8700 x2265 (voice)
    508-457-2310 (FAX)
    sbrosnahan@usgs.gov

Why was the data set created?

The objective of obtaining these ground control points was to constrain the photogrammetric products constructed from the aerial images taken, by providing survey-quality ground validation, which far exceeds the accuracy that can be provided from the photo geolocations alone. Transect points are used to validate the final accuracy of the products, and ground control points are used to geolocate the products as accurately as possible.

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: 08-Oct-2018 (process 1 of 2)
    Ground control points and transect points, are listed in the CSV file 2018015FA_PlumIsland_GCP.csv. Targets and transect measurements were exported from the data collectors as text file in the RW5 format and then processed (referenced to the base OPUS rapid static solution) and exported to comma-separated values (CSV) files using the Carlson Report Generator for a SurvCE RW5 Report (https://www.carlsonemea.com/cwa/report ). Rover datasets were combined and manually edited to filter by transect point or ground control point and extraneous columns were removed. The target data are used as an input to the Agisoft Photoscan or Pix4D software to control the data horizontally and vertically. The transect points collected within the study area are used to ground truth data products (Point Cloud, DEM and Orthomosaic) created in Agisoft Photoscan, and Pix4D. Person who carried out this activity:
    U.S. Geological Survey, Woods Hole Coastal and Marine Science Center
    Attn: Sandra Brosnahan
    Physical Scientist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    U.S.A.

    508-548-8700 x2265 (voice)
    508 457 2310 (FAX)
    Sbrosnahan@usgs.gov
    Date: 06-Aug-2020 (process 2 of 2)
    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)
    vatnipp@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?
    Spectra Precision SP80 GNSS receivers were used to collect the ground control points and transect coordinates.
  2. How accurate are the geographic locations?
    Horizontal positions were determined with GNSS rovers receiving real-time differential corrections from a GNSS base station established over a temporary benchmark. The base station was a Spectra model SP80 GNSS receiver with UHF radio and external antenna mounted on a tripod. The antenna height was 2.25 m. The coordinates of the reference point were determined from an ultra-rapid precise orbit On-line Positioning User Service (OPUS) solution. Spectra Precision model SP80 GNSS receivers were also used as rovers, which linked via Bluetooth to a data collector (Carlson CHC LT30 Handheld Terminal running Carlson SurvCE v. 4.06 software under Windows Mobile v. 6.1 Professional operating system). Rover antennas were mounted on 2-m survey rods with bubble levels and 5-cm (2-inch) sand feet. Conversions from satellite coordinates to NAD83(2011) UTM zone 19N (EPSG::6348) and NAVD88 were made by Carlson SurvCE software in the data collector. Horizontal accuracy based on the reoccupation of a stake locations was 1.5 cm. The uncertainty of OPUS fixes for the RTK-GPS base stations adds another .26 cm of uncertainty, therefore, the theoretical horizontal accuracy of the GCP and transect points is + or - 1.76 cm.
  3. How accurate are the heights or depths?
    Vertical positions were determined with the GNSS rovers receiving real-time differential corrections from a GNSS base station established over a temporary benchmark. The combined vertical uncertainty of OPUS fixes for the RTK-GPS base stations, and the ground control and transect locations is 0.54 cm.
  4. Where are the gaps in the data? What is missing?
    Locations for all of the ground control points and transect points collected are listed in the CSV text file.
  5. How consistent are the relationships among the observations, including topology?
    The CSV file lists the locations for all ground control and transect points. The columns contain, in order, original ID, northing, easting, elevation, date collected, and whether it's a target or transect. The target names (ORIGINAL_ID) are uniquely named (e.g P1, T20, T31); each transect (consisting of several GPS fixes along a survey line) has a unique location, however the points for that transect are all named similarly. Targets included commercial targets (4 ft x 4 ft x 4-mil thick PVC plastic sheets with black and white diamond patterns and grommets in corners; Berntsen International, Inc. product number AT48IC-STK), plywood targets (2 ft x 2 ft x 1/2-inch thick plywood boards painted with black and white squares). The commercial targets were designated Tnn and the plywood targets were designated Pnn, where nn is the one or two digit target number. GPS rover instruments were used by field crews to map targets for ground control points.

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 (USGS) as the source of this information.
  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

    1-888- 275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? The dataset contains the CSV file of ground control and transect points (2018015FA_GCP_PlumIsland.csv), a browse graphic showing the location of the points (2018015FA_gcptrans_browse.jpg), and CSDGM metadata in XML format.
  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 U.S. Geological Survey 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?
  5. What hardware or software do I need in order to use the data set?
    Adequate computer capability is the only technical prerequisite for viewing data in digital form.

Who wrote the metadata?

Dates:
Last modified: 06-Aug-2020
Metadata author:
Sandra Brosnahan
U.S. Geological Survey
Physical Scientist
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2265 (voice)
508-457-2310 (FAX)
sbrosnahan@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P9O9NSRK/2018015FA_GCP_PlumIsland.faq.html>
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