Geotagged Low-Altitude Aerial Imagery From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, on January 9, 2017

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Frequently anticipated questions:


What does this data set describe?

Title:
Geotagged Low-Altitude Aerial Imagery From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, on January 9, 2017
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 this field activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-0005-FA. Drone mapping was conducted at Town Neck Beach and adjacent Spring Hill Beach (January 9 only) 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, Geotagged Low-Altitude Aerial Imagery From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, on January 9, 2017: 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: -70.4882
    East_Bounding_Coordinate: -70.4519
    North_Bounding_Coordinate: 41.7712
    South_Bounding_Coordinate: 41.7549
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Jan-2017
    Ending_Date: 09-Jan-2017
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: remote-sensing image
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 3000 x 4000, type Pixel
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: IGS08 (EPOCH:2017.8707)
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    There are no additional attributes besides the tags described in data quality section associated with these images.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2017-005-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
    U.S. Geological Survey
    Woods Hole, MA

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

Why was the data set created?

This dataset consists of overlapping aerial images obtained on January 9, 2017 that can be used with photogrammetric processing software to create point clouds, digital elevation models, and orthophoto mosaics.

How was the data set created?

  1. From what previous works were the data drawn?
    geotagged photos from field activity 2017-005-FA (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Geotagged photos collected from a UAS during field activity 2017-005-FA.

    Online Links:

    Type_of_Source_Media: disc
    Source_Contribution:
    These JPEG images were collected with an integrated DJI FC300X camera mounted on a DJI Phantom 3 quadcopter unmanned aerial system (UAS). The camera used on the UAS acquired photos 4000 x 3000 pixels (12 Megapixels). The camera orientaion for all flights was "down", aimed directly below the UAS. Horizontal positions and elevations were recorded in the UAS onboard navigation and applied to the images during the flight. These JPEG images may be used with photogrammetric software to produce geolocated point clouds, digital elevation models, orthophoto mosaics, and other products.
  2. How were the data generated, processed, and modified?
    Date: 31-Oct-2017 (process 1 of 1)
    A DJI Phantom 3 quadcopter UAS was flown by Peter Traykovski to acquire these images. They were geotagged in flight by the UAS. It used local time, so an adjustment to GMT was made (see first parameter of step 1 below). They were also processed to add USGS required information to the EXIF headers and renamed to unique file names. These steps are described here:
    1. ExifTool (https://www.sno.phy.queensu.ca/~phil/exiftool/, version 10.64) was used to add required attribution tags to all the photos. The the command used to update the tags was: exiftool -AllDates+=4 -CopyrightNotice="Public Domain - please credit U.S. Geological Survey " -ImageDescription="Photographs of Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-005-FA " -Caption-Abstract="Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-005-FA " -Caption="Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-005-FA " -sep ", " -keywords="Town Neck Beach, Sandwich, Massachusetts, 2017-005-FA, UAS, aerial imagery, USGS " -comment="Photo from down-looking UAS camera during survey 2017-005-FA." -Credit="U.S. Geological Survey" -Contact="WHSC_data_contact@usgs.gov " -Artist="Peter Traykovski" *.JPG
    2. All the JPEG images were renamed with Namexif (version 1.7, http://www.digicamsoft.com/softnamexif.html) to ensure unique filenames and compliance with USGS Coastal and Marine Geology Program's best practices for image naming convention. Images were renamed with a survey ID prefix followed by a local USGS UID, which corresponds to a distinct UAS project; a camera ID that distinguishes among the cameras by make, model, and camera number; the image acquisition date and coordinated universal time (UTC) in ISO8601 format; and a suffix with the original image name. For example, image name '2017027FA_U029DJP4_20170428T092440Z_DJI_0678.JPG', 2017027FA is the survey ID, U029 is the internal identifier code, DJP4 is the internal camera ID, 20170428 is the UTC date informat YYYYMMDD. A 'T' is used to separate UTC date from UTC time in format HHMMSS followed by a Z, and DJI_0678.JPG is the original raw photo name appended to the end of the new filename. Person who carried out this activity:
    Ellyn Montgomery
    U.S. Geological Survey
    Oceanographer
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2356 (voice)
    508-457-2310 (FAX)
    emontgomery@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 camera used on the UAS was a DJI FC300X that acquired photos 4000 x 3000 pixels (12 Megapixels), with file sizes generally between 4.5 and 6.5 MB on disc, depending on image complexity. GPS locations were recorded in the EXIF portion of the images. The GPS used on the UAS has practical accuracies of 3 meters horizontally and 10 m vertically, and the time stamps are accurate to better than 1 millisecond. However, the altitudes recorded in the EXIF portion of the image metadata include uncorrected offsets and may be biased by as much as 250 m. The relative altitudes stored in the XMP portion of the image metadata are accurate to +/- 10 m.
  2. How accurate are the geographic locations?
    Horizontal positions recorded by the UAS GPS were written directly into the EXIF portion of the images during the flights. Horizontal locations are considered accurate to approximately 3 meters, but may be off by as much as 10 meters.
  3. How accurate are the heights or depths?
    Vertical positions recorded by the UAS GPS were written directly into the metadata (EXIF and XMP) portions of the images during the flights. The altitude measurements are accurate to approximately +/- 10 m, but uncorrected offsets in the take-off altitude introduced biases of as much as 250 meters in the EXIF tag "Absolute Altitude". The most acccuate altitude information can be read from the "Relative Altitude", which is stored in the XMP portion of the image. These altitudes are accurate to approximately +/- 10 m.
  4. Where are the gaps in the data? What is missing?
    UAS flights were conducted to map Town Neck Beach and adjacent Spring Hill Beach in Sandwich, MA on January 9, 2017. Gaps in sequential photos exist because some photos were deleted because, for example, of overexposure, or to avoid multiple photos of the landing area. GPS times were not recorded by the DJI firmware, but the local times in the EXIF tag "DateTime" are accurate.
  5. How consistent are the relationships among the observations, including topology?
    All aerial photographs were acquired by with the integrated DJI FC300X camera mounted on a DJI Phantom 3 quadcopter unmanned aerial system (UAS). Images were collected along pre-planned lines with 50 to 60% cross-track overlap. Flight lines were oriented approximately northwest/southeast, roughly parallel to the shoreline. Flights lasted the duration of the UAS battery life (maximum about 22 minutes) or until the flight was completed or aborted. The flight lines and camera shutter timing were planned to record images with 65 to 70% along-track overlap.

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? This data release includes raw data in the form of geotagged aerial images in JPEG format. All 1041 aerial images are distributed in a zip file named 2017005FA_U020_Sandwich.zip.
  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?
    Use of this file requires software capable of opening JPEG images and, if desired, capable or reading the associated EXIF information.

Who wrote the metadata?

Dates:
Last modified: 28-Jan-2019
Metadata author:
Ellyn Montgomery
U.S. Geological Survey
Oceanographer
U.S. Geological Survey
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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