Digital surface model representing Marconi Beach, Wellfleet during field activity 2021-022-FA on March 17, 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital surface model representing Marconi Beach, Wellfleet during field activity 2021-022-FA on March 17, 2021
Abstract:
The data in this publication map the beach and nearshore environment at Marconi Beach in Wellfleet, MA and provide regional context for the 2021 CoastCam installation that looks out at the coast shared by beachgoers, shorebirds, seals, and sharks. These data were collected as part of field activity 2021-022-FA and a collaboration with the National Park Service at Cape Cod National Seashore to monitor the region that falls within the field of view of CoastCam CACO-02, which are two video cameras aimed at the beach. Starting in February and ending in March 2021, U.S Geological Survey and Woods Hole Oceanographic Institute (WHOI) scientists conducted field surveys to collect position and orientation information for the CoastCam cameras and map the field of view. Two new reference marks were established in the Marconi Beach parking area to establish ground control for future surveys. Elevation data were collected using a real time kinematic – satellite navigation system (RTK-GNSS) receiver attached to a pole and walked on the beach. Point data of the beach face were collected along transects. Grain-size analysis was performed on sediment samples collected with a spade along multiple profiles from the bluff base to the intertidal zone. Aerial images of the beach for use in Structure-from-Motion were taken with a camera (Ricoh GRII) and a post-processed kinematic (PPK) system attached to a helium powered balloon-kite (Helikite) and high-precision GPS targets (AeroPoints) were used as ground control points. Bathymetry was collected in the nearshore using a single-beam echosounder mounted on a surf capable self-righting electric autonomous survey vehicle. Agisoft Metashape (v. 1.7.2) was used to create a digital elevation model with the collected imagery and this was merged with the bathymetry in MATLAB (v. 2020) to create a continuous topobathy product.
Supplemental_Information:
This digital elevation model, as constructed using structure-from-motion from the images in the 2021022FA_Marconi_f1.zip file, represents 0.4426 square kilometers of Marconi Beach in view of the CoastCam cameras on March 17, 2021. The GeoTIFF is not cloud optimized. For more information about the WHCMSC Field Activity, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-022-FA.
  1. How might this data set be cited?
    U.S. Geological Survey, 2021, Digital surface model representing Marconi Beach, Wellfleet during field activity 2021-022-FA on March 17, 2021: data release DOI:10.5066/P9POZ9VH, U.S. Geological Survey, Coastal and 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.

    Over, J., Sherwood, C., Traykovski, P., and Marsjanik, E., 2021, Topographic and bathymetric data, sediment samples, structure from motion imagery, and reference mark data collected at Marconi Beach, Wellfleet in winter 2021, U.S Geological Survey Field Activity 2021-022-FA.: data release DOI:10.5066/P9POZ9VH, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Over, J.R., Sherwood, C.R., Traykovski, P., and Marsjanik, E., 2021, Topographic and bathymetric data, sediment samples, structure from motion imagery, and reference mark data collected at Marconi Beach, Wellfleet in winter 2021, U.S Geological Survey Field Activity 2021-022-FA: U.S Geological Survey data release, https://doi.org/10.5066/P9POZ9VH.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -69.96628530
    East_Bounding_Coordinate: -69.96064525
    North_Bounding_Coordinate: 41.89857855
    South_Bounding_Coordinate: 41.88969178
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2021-022-FA/data/Topobathy/Topography/2021022FA_Marconi_DSM_browse.JPG (JPEG)
    Elevation-colored image of topography data collected on Marconi Beach, Wellfleet MA
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 17-Mar-2021
    Currentness_Reference:
    ground condition; represents the state of the beach on March 17, 2021
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  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 3928 x 1828, type Pixel
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 19
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -69.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 0.25
      Ordinates (y-coordinates) are specified to the nearest 0.25
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1983 (National Spatial Reference System 2011).
      The ellipsoid used is GRS_1980.
      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
      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?
    2021022FA_Marconi_topography_25cm.tif
    A raster dataset (GeoTIFF format) with encoded elevation values of Marconi Beach in Wellfleet, MA on March 17, 2021. Pixel resolution is 25 cm. (Source: U.S. Geological Survey, Coastal and Marine Hazards and Resources Program)
    Value
    Surface elevation orthometric height (m) in NAD83 (2011) UTM Zone 19N, NAVD88 using Geoid 2018 (no data value = -999) (Source: U.S. Geological Survey, Woods Hole Coastal and Marine Science Center)
    ValueDefinition
    -999No data
    Range of values
    Minimum:-1.633
    Maximum:21.499
    Units:meters
    Entity_and_Attribute_Overview:
    Pixels represent elevation in meters relative to North American Vertical Datum of 1988 (NAVD88). GeoTIFF was created from the dense point cloud in Agisoft Metashape without interpolation enabled. The Metashape software assigns a no-data value of -999 to this elevation surface
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-022-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?
    Jin-Si Over
    U.S. Geological Survey
    Geographer
    U.S. Geological Survey
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov

Why was the data set created?

May be used as a high-resolution elevation dataset of Marconi Beach for use by the public, researchers, and others to observe ground conditions and change over time.

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: 18-May-2021 (process 1 of 2)
    Digital Surface Model was created in Agisoft Metashape v. 1.7.1 using the following general steps (see Over and others, 2021 for a more detailed explanation of methodology):
    1. Project created and imagery (located in larger work citation 2021022FA_Marconi_f1.zip) and position (located in larger work citation 2021022FA_Marconi_f1_photolocations.csv) data were brought in using the NAD83(2011) datum. 2. Photos were aligned at high accuracy (the pixels are not subsampled for increased processing speed) with a keypoint limit of 40,000 and unlimited tie points. Alignment uses the positions and matching pixels between images to create point clouds and put the imagery into a real-world relative spatial context. Photos that failed to align/find tie points contained breaking waves and water but are kept in the project to reconstruct the orthomosaic because they are still spatially orientated even if they do not contribute to the elevation model. Metashape software refined and optimized the camera positions and lens model in a least squares sense to minimize reprojection error or the distance between the measured points and the software created points. 3. Nine ground control points (GCPs) (2021022FA_Marconi_nav_AeroPoints.csv located in the larger work citation were added to the project in NAD83(2011) and manually identified in the images as markers. 4. A dense point cloud was generated using high quality (images are not subsampled) and a low frequency filtering algorithm. Accuracies for the GCPs were set 0.01 m and accuracies for the camera positions were set to 5 cm, resulting in a total camera position error of 0.05m and a GCP error of 0.016 m. The dense point cloud was then edited to remove noise by filtering by point confidence before generating a digital elevation model (the software calls all surfaces digital elevation models, but technically it is a digital surface model because it includes vegetation and canopy returns, a DEM or terrain model would be only bare earth returns). 5. The digital surface model is exported from the software at a resolution of 25 cm and in NAD83(2011)/UTM Zone 19N (ESPG:6348) and GEOID18 NAVD88 in meters. 6. Product was clipped in ArcDesktop (v. 10.7) to the western most corners of the bathymetry GeoTIFF in the larger work citation to simplify the process of joining the two products together. Person who carried out this activity:
    Jin-Si Over
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov
    Date: 11-Jan-2022 (process 2 of 2)
    Updated the metadata file to have the online linkage for the larger work citation in the format of a URL. Modified the filename to replace 'topography' with 'DSM' to match the data release. Modified the download link to the filename with 'DSM' instead of 'topography'. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Over, Jin-Si R., Ritchie, Andrew C., Kranenburg, Christine, Jennifer (Jenna) A. Brown, Buscombe, Daniel D., Noble, Tom, Sherwood, Christopher R., Warrick, Jonathan, and Wernette, Phillipe, 2021, Processing coastal imagery with Agisoft Metashape Professional Edition, version 1.6-Structure from motion workflow documentation: Open-File Report 2021-1039, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    This publication includes the general methodology for processing imagery in Metashape to produce DEMs and ortho products.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The positional information used on the Helikite and ground control point datasets and metadata are available in the imagery and navigational components of the larger work citation.
  2. How accurate are the geographic locations?
    Navigation information was acquired from a GNSS receiver (EMLID Reach M2) in PPK mode with a Multi-band GNSS antenna that has an estimated horizontal accuracy of 2-5 cm.
  3. How accurate are the heights or depths?
    The location information was acquired from a GNSS receiver (EMLID Reach M2) in PPK mode with a Multi-band GNSS antenna and hotshoe adapter with an estimated vertical accuracy of 2-5 cm. The ground control points used have centimeter vertical accuracies.
  4. Where are the gaps in the data? What is missing?
    The structure-from-motion process that builds the DSM uses all the available imagery and location information at the start; however, not all images may align in the software to produce the final product. The elevation surface was clipped to roughly match the lateral extents of the bathymetry data. This topographic surface does not have interpolated elevation data to fill holes. 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?
    All data fall into expected ranges except for points near and offshore of the waterline, where the data returned can be noisy and may result in erroneous measurements. This is a digital surface model (DSM) and includes returns from vegetation.

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. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Not for navigational use. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
  1. Who distributes the data set? (Distributor 1 of 1)
    Jin-Si Over
    U.S. Geological Survey
    geographer
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2269 (voice)
    jover@usgs.gov
  2. What's the catalog number I need to order this data set? GeoTIFF file 2021022FA_Marconi_topography_25cm.tif as a 32-bit floating point digital surface model (DSM).
  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: 11-Jan-2022
Metadata author:
Jin-Si Over
U.S. Geological Survey
geographer
U.S. Geological Survey
Woods Hole, MA

508-548-8700 x2269 (voice)
jover@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/field_activities/2021_022_fa/2021022FA_Marconi_DSM.faq.html>
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