Surveyed Positions of Ground Control Points and Photos of In-Place Features Used as Ground Control Points Associated With Images Collected During Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017 (Text Files and Photos)

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Frequently anticipated questions:


What does this data set describe?

Title:
Surveyed Positions of Ground Control Points and Photos of In-Place Features Used as Ground Control Points Associated With Images Collected During Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017 (Text Files and Photos)
Abstract:
Low-altitude (80-100 meters above ground level) digital images of Town Neck Beach in Sandwich, Massachusetts were obtained from a camera mounted on a small unmanned aerial system (UAS; also known as a drone). Imagery was collected at close to low tide on seven days to observe changes in beach and dune morphology. The images were geolocated by using the single-frequency geographic positioning system aboard the UAS. Ground control points (GCPs) were established by using temporary targets on the ground, which were located by using a real-time kinematic global navigation satellite system (RTK-GNSS) base station and rovers. The GCPs can be used as constraints during photogrammetric processing. Transect points were collected by using the same RTK-GNSS system; these can be used to evaluate photogrammetric products. This data release includes georeferenced images, image-location files, GCPs, and transect points. Collection of these data was supported by the U.S. Geological Survey Coastal and Marine Geology Program and were conducted under USGS field activity numbers 2017-005-FA, 2017-008-FA, 2017-010-FA, 2017-014-FA, 2017-027-FA, 2017-029-FA, and 2017-050-FA.
Supplemental_Information:
For more information about the field activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-005-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-008-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-010-FA,https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-011-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-014-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-027-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-029-FA, https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-050-FA. Note that on January 9 (2017-005-FA), the survey was extended slightly east and south to encompass the adjacent Spring Hill Beach; the other days only cover Town Neck Beach. Drone mapping was conducted at Town Neck Beach in Sandwich, Massachusetts beginning in 2015. The digital images, Ground Control Points and transect data from a calendar year are released together. This product contains the data collected in 2017.
  1. How might this data set be cited?
    U.S. Geological Survey, 2019, Surveyed Positions of Ground Control Points and Photos of In-Place Features Used as Ground Control Points Associated With Images Collected During Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017 (Text Files and Photos): data release DOI:10.5066/F7QC02RM, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Sherwood, C., Traykovski, P., Montgomery, E., Borden, J., Brosnahan, S., Irwin, B., Marsjanik, E., Martini, M., and Suttles, S., 2019, Geotagged Low-Altitude Aerial Imagery, From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, With Associated Ground Control Points, and Transects collected on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017: data release DOI:10.5066/F7QC02RM, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Sherwood, C.R., Traykovski, P.A., Montgomery, E.T., Borden, J., Brosnahan S.M., Irwin, B.J., Marsjanik, E.D., Martini, M.A., and Suttles, S.E., 2019, Geotagged low-altitude aerial imagery from unmanned aerial systems flights over Town Neck Beach in Sandwich, Massachusetts, with associated ground control points and transects, collected on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017: U.S. Geological Survey data release, https://doi.org/10.5066/F7QC02RM.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.4880
    East_Bounding_Coordinate: -70.4537
    North_Bounding_Coordinate: 41.7703
    South_Bounding_Coordinate: 41.7553
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 09-Jan-2017
    Currentness_Reference:
    ground condition temporary markers and in-place features
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: digital text files and digital raster images
  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
    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: -69.00000
      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.
      The ellipsoid used is Geodetic Reference System 80.
      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 (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?
    2017SandwichTNB_GCPs.zip
    The files contain target and in-place feature positions surveyed at Town Neck Beach, Sandwich, MA to provide ground control points to constrain the photogrammetric products, and photos of the in-place features to identify them in aerial imagery. (Source: U.S. Geological Survey)
    Label
    Target/GCP identifier (Source: rover operator) character set
    X/Easting (m NAD83(2011) Zone 19N)
    Easting in meters referenced to NAD83(2011) UTM Zone 19 North. (Source: SP80 GNSS receiver)
    Range of values
    Minimum:376000
    Maximum:380000
    Units:meters
    Resolution:1.0E-4
    Y/Northing (m NAD83(2011) Zone 19N)
    Northing in meters referenced to NAD83(2011) UTM Zone 19 North. (Source: SP80 GNSS receiver)
    Range of values
    Minimum:4620000
    Maximum:4630000
    Units:meters
    Resolution:1.0E-4
    Z/Elevation (m NAVD88)
    Elevation referenced to NAVD88. (Source: SP80 GNSS receiver)
    Range of values
    Minimum:-1
    Maximum:7
    Units:meters
    Resolution:1.0E-3
    Entity_and_Attribute_Overview:
    Eight text files and 22 digital images (.jpg files) are in the .zip. Seven files contains the locations and elevations of the GCPs on a specific date. Each file contains one header line, followed by lines with 4 columns of comma-separated values. The header line describes the column contents as follows: #Label, X/Easting (m NAD83(2011) Zone 19N), Y/Northing (m NAD83(2011) Zone 19N), Z/Elevation (m NAVD88). Subsequent lines contain the labels and coordinates for each GCP deployed on that day. The labels identify which type of target was used, where Txx indicates the 4-ft square PVC plastic targets, and Pxx indicates the 2-ft square plywood targets (xx is the target number in both), and H indicates the orange disk used as the UAS landing spot. Each file has a different number of data records: 2017-01-09_SandwichTNB_GCPs.txt has 39, 2017-01-25_SandwichTNB_GCPs.txt has 41, 2017-02-14_SandwichTNB_GCPs.txt has 26, 2017-03-16_SandwichTNB_GCPs.txt has 26, 2017-04-28_SandwichTNB_GCPs.txt has 26, 2017-05-04_SandwichTNB_GCPs.txt has 27, 2017-09-18_SandwichTNB_GCPs.txt has 26. The eighth .txt file contains the same information for the in-place features surveyed on various dates. This file (2017_All_SandwichTNB_in_place_GCPs.txt) has the same format and contains 11 records after the header. The 22 digital image files are in JPEG format. The image file names of photos of in-place features are named according to the feature labels and the date of the photograph. If multiple photos of the same feature are included, numbers are included in the filenames. For example, E_BWALK_FAT_1_25Jan2017.jpg is one of two photos of E_BWALK_FAT taken on January 25, 2017.
    Entity_and_Attribute_Detail_Citation:
    USGS Field Activities 2017-005-FA, 2017-008-FA, 2017-010-FA, 2017-011-FA, 2017-014-FA, 2017-027-FA, 2017-029-FA, 2017-050-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?
    Sandra Brosnahan
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA

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

Why was the data set created?

This dataset consists of locations of targets deployed and surveyed on January 9, January 25, February 14, March 16, April 28, May 4, and September 18, 2017, and in-place features surveyed on January 25, February 24, and 16 March, 2017 that can be used as ground control points (GCPs) to constrain photogrammetric processing of imagery collected on the same days.

How was the data set created?

  1. From what previous works were the data drawn?
    GPS ground control point locations from USGS field activities 2017-005-FA, 2017-008-FA, 2017-010-FA, 2017-014-FA, 2017-027-FA, 2017-029-FA, 2017-050-FA (source 1 of 1)
    Type_of_Source_Media: .csv file
    Source_Contribution:
    The ground control points (GCPs) may be used to constrain the photogrametric products produced from aerial images taken on the same day at Town Neck Beach, Sandwich, MA.
  2. How were the data generated, processed, and modified?
    Date: 18-Sep-2017 (process 1 of 1)
    All targets and transect locations were measured with an RTK-GNSS system by the USGS field crew at Town Neck Beach, Sandwich, MA during daylight around the time of low tide. Two kinds of targets were used: 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), and 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 "Txx" and the plywood targets were designated "Pxx", where xx is the target number. 'PM' may be appended to a label, if so it indicates a second occupation later in the afternoon. In-place features are associated with photos to help identify them in aerial imagery. See Data_Quality_Information for a complete description. See Horizontal and vertical Positional_Accuracy_Report for a complete description of the survey methods. Data from the survey instruments was produced in horizontal coordinate reference system (CRS) NAD83(2011) UTM Zone 19 N (meter), and the vertical CRS NAVD88. These were reformatted (e.g., column locations were changed) when were loaded into Photoscan during photogrammetry processing. They were subsequently exported from Photoscan as comma-separated text (.txt) files with a two-line header. We hand-edited those files to replace the two-line header supplied by Photoscan with the following header: "#Label,X/Easting (m NAD83(2011) Zone 19N),Y/Northing (m NAD83(2011) Zone 19N),Z/Elevation (m NAVD88)". Process date is the same as collection date, which for the 8 events is January 9, January 25, February 14, February 24, March 16, April 28, May 4 and September 18. The process date indicated is the last of those events. Person who carried out this activity:
    Sandy Brosnahan
    U.S. Geological Survey
    Physical Scientist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2265 (voice)
    508-457-2310 (FAX)
    sbrosnahan@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 locate the targets used as ground control points and transect coordinates. One was configured as a base station and established at a fixed, known location, and broadcast differential corrections to rovers in real time. On various days, one or two SP80 receivers and/or a Spectra Precision model ProMark 800 GNSS receiver functioned as rovers that received corrections from the base and were used to locate targets that served as ground control points and measure transect points. The base location was determined via localization with a rover positioned on a local reference point designated BMOPUS. The overall horizontal accuracy of the target locations, based on the accuracy of the reference point and repeat measurements of targets and other known locations was 1.5 cm and the vertical accuracy was 0.5 cm.
  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 benchmark on the corner of a concrete pad under the trash bins at the east end of the Town Neck Beach parking lot, Sandwich, MA. The base station was a Spectra model SP80 GNSS receiver with UHF radio and external antenna mounted on a separate tripod. The antenna height was 2.25 m. The coordinates of the reference point (designated BMOPUS) were determined from precise orbit On-line Positioning User Service (OPUS) solutions using GPS data collected during five 2- to 7-hour occupations between November 2015 and December 2016. The final values are the averages of the five positions, and the uncertainty is the quadrature sum of the range (minimum to maximum values) among the five measurements and the range for individual measurements, as reported by OPUS. The coordinates (uncertainty) in NAD83(2011) (Epoch:2010.0000) UTM Zone 19, elevation NAVD88 (geoid 12B) for the reference point BMOPUS are: Northing (m) 4624914.408 (0.0067) meters, Easting 376707.744 (0.0175) meters, Orthometric elevation 2.692(0.0398) meters. The coordinates of the targets and in-place features were measured with rovers with an estimated precision of +/- 3 cm (horizontal) and +/-1.6 cm (vertical). Combined with the uncertainty of the reference point, the overall estimated accuracy of target locations used for GCPs is +/- 3.5 cm (horizontal) and +/-4.3 cm (vertical).
  3. How accurate are the heights or depths?
    Vertical positions were determined with GNSS rovers receiving real-time differential corrections from a GNSS base station established over a temporary benchmark on a concrete pad under the trash bins at the east end of the Town Neck beach parking lot, Sandwich MA. (see Horizontal_Positional_Accuracy_Report for a complete description of the survey methods).
  4. Where are the gaps in the data? What is missing?
    On January 9 (2017-005-FA), the survey was extended slightly east and south to encompass the adjacent Spring Hill Beach; the other days only cover Town Neck Beach. The data is complete for each field activity. Positions of all of the temporary targets that serve as ground control points deployed each day are listed in the text files. As suggested by the non-sequential numbering of some of the in-place feature labels, not all of the in-place features that were survyed are included. However, all of the in-place features that had identifying photos and were deemed useful for constraining the photogrammetric reconstruction are included.
  5. How consistent are the relationships among the observations, including topology?
    There is one text file for targets per survey day and one additional file for in-place features. Each target file lists the positions of each temporary target with horizontal coordinates in NAD83(2011) UTM Zone 19 North (meters), and vertical coordinates in NAVD88 GEOID 12b (meters). Two types of targets were always used, and are distinguished by labels in the first column of the data file: Txx indicates the PVC targets and Pxx indicates the plywood targets (where xx is the target number). On two days (January 9 and January 25) round targets with binary codes readable by Agisoft Photoscan software were used; these are denoted as "target xx", where xx corresponds the encoded number. 'PM' may be appended to a label, if so it indicates a second occupation later in the afternoon. On one day (May 4) a circular orange target with a large H was used as a drone landing site and a ground control point, and is labeled as H in the file. The in-place features file lists the surveyed locations of pre-existing features visible from the air. In-place features were surveyed using the same equipment and methods and recorded in the same coordinate system. In-place features were surveyed on January 25, February 24, and March 16. One or more photos of each in-place feature were taken to allow users to match the features with their coordinates. The feature labels are descriptive: 65_FRMN_GRATE refers to a drainage grate near 65 Freeman Avenue (three photos); BBR1 (two photos), BBR5 (one photo), and BBR9 (one photo) refer to features on Bay Beach Road; E_BWALK_FAT (two photos) refers to a wide section in the marsh boarwalk; E_BWALK_T (one photo) refers to the junction in the marsh boardwalk; FMN_GRATE_N (three photos) refers to a drainage grate on the north side of the junction of Freeman Avenue and Wood Avenue; JR4 (six photos) refers to a rock on a beach groin surveyed by Jonathan Borden; and WHITECAP_PATH (three photos) refers to a feature on Whitecap Path. In two cases (BBR1 and E_BWALK_T) the feature was surveyed on two occasions; these labels include _1 and _2 to distinguish them. Photos of in-place features are named according to the feature labels and the date of the photograph. If multiple photos of the same feature are included, numbers are included. For example, E_BWALK_FAT_1_25Jan2017.jpg is one of two photos of E_BWALK_FAT taken on January 25, 2017.

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? A zip file contains 23 JPEG images and 8 text files. Seven files contains the locations and elevations of the GCPs on a specific date (2017-01-09_SandwichTNB_GCPs.txt, 2017-01-25_SandwichTNB_GCPs.txt, 2017-02-14_SandwichTNB_GCPs.txt, 2017-03-16_SandwichTNB_GCPs.txt, 2017-04-28_SandwichTNB_GCPs.txt, 2017-05-04_SandwichTNB_GCPs.txt, 2017-09-18_SandwichTNB_GCPs.txt). The remaining text file (2017_All_SandwichTNB_in_place_GCPs.txt) contains locations and elevations for the in-place features (represented by the JPEG images).
  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?

Who wrote the metadata?

Dates:
Last modified: 28-Jan-2019
Metadata author:
Ellyn Montgomery
U.S. Geological Survey
Oceanographer
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2356 (voice)
508-457-2310 (FAX)
emontgomery@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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