Geotagged Low-Altitude Aerial Imagery From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, on May 4, 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 May 4, 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=2017-029-FA. 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, Geotagged Low-Altitude Aerial Imagery From Unmanned Aerial Systems Flights Over Town Neck Beach, in Sandwich, Massachusetts, on May 4, 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: -70.4880
    East_Bounding_Coordinate: -70.4725
    North_Bounding_Coordinate: 41.7715
    South_Bounding_Coordinate: 41.7610
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 04-May-2017
    Ending_Date: 04-May-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 3264 x 4352, 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 2017-029-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 May 4, 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?
    aerial images from field activity 2017-029-FA (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Geotagged photos collected from a UAS during field activity 2017-029-FA.

    Online Links:

    Type_of_Source_Media: disc
    Source_Contribution:
    These JPEG images were collected with a Ricoh GRII HD camera labeled 'RI99', where 'RI' indicates a Ricoh camera, and the following 2 digits normally indicate the camera ID. In this case, '99' indicates that the camera ID is unknown. The camera was mounted on a 3DR Solo quadcopter unmanned aerial system (UAS; FAA small UAS registration number FA3R4LWWY9) for each flight. The Ricoh GRII HD cameras used on the UAS acquire photos at 16.2 Megapixels, with file sizes generally between 4 and 6 MB on disc, depending on image complexity. The camera orientaion for all flights was "down", aimed directly below the UAS. Horizontal positions and elevations were recorded in the UAS onboard navigation logs and were derived from a mRo GPS (u-Blox Neo-M8N / 3DR SOLO Upgrade), which receives signals from GPS and GLONASS satellites in WGS84, but is otherwise uncorrected. The navigation data is added to the image EXIF information after the flight as described in the process steps. 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: 02-Apr-2018 (process 1 of 1)
    The UAS GPS and the camera may record in different timezones, therefore, if needed a time offset was used to synchronize the camera and the GPS clocks to UTC. The raw images acquired by the Ricoh camera mounted on the 3DR Solo quadcopter were geotagged using Mission Planner software from Ardupilot.org. The sofware plans and executes the flights then was used to apply the time correction, and apply the positions and elevations logged in the tlog navigation file to the images. The geotagged images were then processed to add additional information required by USGS to the EXIF headers using ExifTools (https://www.sno.phy.queensu.ca/~phil/exiftool/, version: 10.75) and the files were renamed to a unique identifier using Namexif (version 1.7) to avoid any possibility of duplicate names. These steps are described here:
    1) ExifTools was used to update several additional tags for all the photos. The the command used to updated tags was: exiftool -CopyrightNotice="Public Domain - please credit U.S. Geological Survey " -ImageDescription="Photographs of Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-029-FA " -Caption-Abstract="Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-029-FA " -Caption="Town Neck Beach, Sandwich, Massachusetts, USA from survey 2017-029-FA " -sep ", " -keywords="Town Neck Beach, Sandwich, Massachusetts, 2017-029-FA, UAS, aerial imagery, USGS " -comment="Photo from down-looking UAS camera during survey 2017-029-FA." -Credit="U.S. Geological Survey" -Contact="WHSC_data_contact@usgs.gov " -Artist="Sandy Brosnahan" *.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 USGS 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 '2017050FA_U039RI02_20170918T190922Z_B0022888.JPG', 2017050FA is the survey ID, U039 is the internal identifier code, RI02 is the internal camera ID, 20170918 is the UTC date in format YYYYMMDD. A 'T' is used to separate UTC date from UTC time in format HHMMSS followed by a Z, and B0022888.JPG is the original raw photo name appended to the end of the new filename.
    3) Image EXIF DateTime* fields were an hour later than the GPS time in all files. exiftool was run again with -AllDates -=1 to correct the image metadata.
    4) The two 'hours' digits of each filename were decremented to match the GPSTimeStamp using a bash script. 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 Ricoh GRII HD cameras used on the UAS acquires photos at 16.2 Megapixels, with file sizes generally between 4 and 6 MB on disc, depending on image complexity. The GPS used on the UAS has theoretical accuracies of 3 meters horizontally and 10 m vertically.
  2. How accurate are the geographic locations?
    Horizontal positions recorded in the UAS flight logs and later applied to the EXIF portion of the images were derived from a mRo GPS (u-Blox Neo-M8N / 3DR SOLO Upgrade), which receives signals from GPS and GLONASS satellites in WGS84 (G1150) EPSG::7660, but is otherwise uncorrected. 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 in the UAS flight logs and later applied to the EXIF portion of the images are ellipsoidal heights and were derived from a a mRo GPS (u-Blox Neo-M8N / 3DR SOLO Upgrade), which receives signals from GPS and GLONASS satellites, but is otherwise uncorrected. Vertical locations are less accurate than horizontal positions and may be off by more than 10 meters.
  4. Where are the gaps in the data? What is missing?
    Seven UAS flights were conducted to map the Town Neck Beach shoreline in Sandwich, MA on May 4, 2017. There is no flight 2- it was aborted, and no images were collected. During the flights, photographs were captured every 2 seconds. Gaps in sequential 2 second photo intervals exist because some photos were deleted because, for example, of overexposure, or to avoid multiple photos of the landing area.
  5. How consistent are the relationships among the observations, including topology?
    Flights were flown at a target elevation of 80 m along pre-planned lines with 70% cross-track overlap. Two sets of flight lines were flown, one set was approximately northwest/southeast, and the second set was at right angles to the first set. Flights lasted the duration of the UAS battery life (maximum 15 minutes) or until the flight was completed or aborted. Along-track overlap was determined by the image acquisition rate. The camera was set to record images at 2-second intervals, activated before takeoff, and deactivated after landing. Preflight photos of UTC time displayed on an accurate timepiece were captured with the camera and used to monitor camera clock drift. Camera time and UTC time were never different (to a 1 second accuracy) during this survey.

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. The aerial images are distributed in 7 zip files containing images named 2017029FA_U031_Sandwich_f#.zip; where f# indicates the flight number. There is no flight 2- it was aborted, and no images were collected. 2017029FA_U031_Sandwich_f1.zip contains 441 images, 2017029FA_U031_Sandwich_f3.zip contains 358 images, 2017029FA_U031_Sandwich_f4.zip contains 392 images, 2017029FA_U031_Sandwich_f5.zip contains 279 images, 2017029FA_U031_Sandwich_f6.zip contains 343 images, 2017029FA_U031_Sandwich_f7.zip contains 464 images, 2017029FA_U031_Sandwich_f8.zip contains 347 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?
  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 of 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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